ITT: Stupid Questions

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ITT: Stupid Questions Anonymous Mon Aug 11 21:45:13 2014 No.6695842 [Reply] [Original]

I didn't see a stupid questions thread, so I started one.

What is the relationship between matter and energy? I get the one for spacetime. I know any massive object will have internal energy equal to its mass x c, but what is there actual relationship to each other? In a nuclear bomb, nuclei bond such that they release some of the energy held in their nuclear, strong force bonds, right? They don't just turn into energy? Do they? Can energy turn into matter?

Pardon me, I didn't have the Rain Wilson image.

>>	Anonymous Mon Aug 11 21:46:32 2014 No.6695844 Shameless self-bump

>>	Anonymous Mon Aug 11 22:21:27 2014 No.6695884 >>6695842 http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

>>	Anonymous Mon Aug 11 22:49:36 2014 No.6695924 Change? K-Korra...?

>>	Anonymous Mon Aug 11 22:52:43 2014 No.6695932 >>6695924 Is season 3 any good?

Anonymous Mon Aug 11 22:58:13 2014 No.6695948

>>6695932
I like it. Unlike seasons 1-2, the villain's motive and the main theme of the season haven't been forgotten or ruined by the writer..yet. But it's fun, with some good characterization for everyone, 'specially Lin, 'cept Asami.

Umm, need to make this relevant. Uh....Lim: x->0 [abs(1/x)]=infinity?

>>	Anonymous Mon Aug 11 23:06:20 2014 No.6695961 What the heck even is change? Shouldn't time cover that?

>>	Anonymous Mon Aug 11 23:26:36 2014 No.6695991 >>6695948 >Lim: x->0 [abs(1/x)]=infinity Seems right.

>>	Anonymous Mon Aug 11 23:27:48 2014 No.6695994 >>6695961 can you clarify your question?

>>	Anonymous Mon Aug 11 23:28:48 2014 No.6695995 >>6695842 How can I become a god?

Anonymous Mon Aug 11 23:33:39 2014 No.6696003

>>6695994
Not really. I'm a dumb /diy/ guy. I thought the universe was only made out of space, time, energy, and matter. Time is the 4th dimension, the "w" axis. I thout the whole reason that existed was to show how 3d states change.

But it is wikipedia. And clicking on it takes you to some one-paragraph section of another aticle. I would think a fundamental aspect of the universe would deserve its own page.

>>	Anonymous Mon Aug 11 23:34:50 2014 No.6696004 >>6695995 Sell your soul to Satan.

>>	Anonymous Mon Aug 11 23:36:45 2014 No.6696007 >>6695842 Should I date someone who uses infer when she obviously meant imply?

>>	Anonymous Mon Aug 11 23:38:04 2014 No.6696008 >>6696007 Explain the difference. Then proceed to date.

>>	Anonymous Mon Aug 11 23:38:52 2014 No.6696013 >>6696003 I'm not exactly an expert, but I feel like change is a concept used when describing other things. its not some inherent property of the universe

>>	Anonymous Mon Aug 11 23:39:01 2014 No.6696014 >>6696007 Tell her of her mistake. If she realizes her error and changes that whole aspect of their life, she's a keeper

>>	Anonymous Mon Aug 11 23:40:15 2014 No.6696019 >>6696013 Yeah. fuck Wikipedia, I guess. From OP's image, WP says it's an, "element of nature"

Anonymous Tue Aug 12 00:23:46 2014 No.6696070
File: 26 KB, 180x180, gentlemen.png [View same] [iqdb] [saucenao] [google]

Einstein

Energy = Mass x (the speed of light(also known as c))2

or rather

Energy / c2 = Mass

Matter is frozen energy from what I understand
Radioactive matter has a specific half life that decays into different types of radiation

Anonymous Tue Aug 12 03:43:29 2014 No.6696341

probably a very stupid question

Say that you have 3 organisms: Organism A, Organism B, and Organism C.

Organism A and B are part of the same species.
Organism B and C are part of the same species.
Organism A and C are not part of the same species.

Is this possible? I really don't think it is but I'm retarded so who knows. I remember having a vague explanation last night for how it would be possible. I've forgotten it now.

>>	Anonymous Tue Aug 12 04:51:33 2014 No.6696377 >>6696341 Pretty sure its not possible. Simply from the law of identity they are all from the same species. They don't necessarily belong to the same sub-species though.

>>	Anonymous Tue Aug 12 04:58:42 2014 No.6696382 >>6696341 This isn't possible, at least from a logic point of view. If A = B and B = C, then surely A = C

>>	Anonymous Tue Aug 12 05:21:59 2014 No.6696405 What kind of qualifications would one need to become a lowly lab assistant at a good company research lab?

Anonymous Tue Aug 12 05:48:20 2014 No.6696437

>>6695948
>Lim: x->0 [abs(1/x)]=infinity?
approaching from the right (i.e. going down to zero) that is correct but it is usually assumed when you're taking limits to take the limit from both sides (going closer to zero from negatives approaches -infinity).

>>	Anonymous Tue Aug 12 05:55:21 2014 No.6696447 Does neuroscience still generally hold a behaviorist view of emotions? I heard that they do in a thread a bit ago but I haven't been able to find anything confirming or denying this.

>>	Anonymous Tue Aug 12 06:02:35 2014 No.6696459 File: 133 KB, 620x659, StandardModel3.jpg [View same] [iqdb] [saucenao] [google] Why are there so many goddamn stupid particles, and why are their masses so completely arbitrary?

>>	Anonymous Tue Aug 12 06:04:45 2014 No.6696462 >>6696447 If by behaviorist you mean, chemicals controlling your emotional state, then yes. Basically neuroscience treats the brain as a very complex machine. That's the reason I like nueroscience, it is strictly physical and it makes sense.

>>	Anonymous Tue Aug 12 06:07:09 2014 No.6696465 >>6696459 Because that's the way the universe is.

>>	Anonymous Tue Aug 12 06:07:41 2014 No.6696466 >>6696462 But does it stop people from committing suicide

>>	Anonymous Tue Aug 12 06:08:33 2014 No.6696469 >>6696405 Phd and a recommendation letter form your professor.

>>	Anonymous Tue Aug 12 06:10:13 2014 No.6696471 >>6696466 When they figure out how everything in the brain works, then yes. Otherwise nothing can stop people from committing suicides.

Anonymous Tue Aug 12 06:14:28 2014 No.6696477

>>6696341
In a sense yes, but also no.

Biologically organisms are of the same species if they can produce offspring that can produce more offspring.
Thus, for example if organisms A and C had a recessive lethal gene, they couldn't produce living children and thus technically wouldn't be of the same species.
In reality species are defined by populations rather than single organisms.
There probably could exist a situation in which populations [A and B] and [B and C] could mate, but populations A and C couldn't, but likely A and B would be grouped as a single species, and C as another which can sometimes successfully produce offspring with the species that is A and B.

-- I also have a question that I can't figure out:
Is the equation sin(x)sin(y)+cos(x)cos(y)=1 only true if y=x+2*pi*n, where n is an integer? How can I prove this?

>>	Anonymous Tue Aug 12 06:15:31 2014 No.6696479 >>6696469 i only have a bachelors

Anonymous Tue Aug 12 06:17:53 2014 No.6696483

>>6696462
That isn't what I mean, behaviorists regarded emotion as only a form of behavior and defined the emotions not as feelings but defined by facial features.
this is the quote that lead me to ask this.
>Neuroscience has its own definitions of individual experience that can be measured without even asking the subject how they feel (it specifically talks about measured facial expressions, not self reported feelings)

>>	Anonymous Tue Aug 12 06:39:14 2014 No.6696500 any Australian electrical engineers on here? I'm an electrician wanting to do Electrical Engineering, aside from the maths is the electrical theory that hard/intense? I was taught by an engineer at TAFE so I have a decent knowledge already.

>>	Anonymous Tue Aug 12 06:44:50 2014 No.6696505 Is it wise to jump from computer engineering to physics?

Anonymous Tue Aug 12 07:03:55 2014 No.6696523

>>6696479
It will be hard but not impossible. You'll just have to show them that you can do it.

>>6696483
Emotion is just a control mechanism in your brain, that controls your behavior. You could say that it starts when a certain nucleus produces it's output signal.

http://en.wikipedia.org/wiki/Affective_neuroscience
I think this would help.

>>	Anonymous Tue Aug 12 07:15:02 2014 No.6696531 Whats the term for a 50% fatality rate in a population? used in medicine or whatever. LDL 50?

>>	Anonymous Tue Aug 12 07:15:10 2014 No.6696532 >>6696523 >You'll just have to show them that you can do it. And how would i do that? I don't even have any undergrad level publications. Came quiet close on one once but just didn't happen.

>>	Anonymous Tue Aug 12 07:30:26 2014 No.6696550 >>6696532 Either a recommendation or history of publications and project you participated in.

>>	Anonymous Tue Aug 12 08:25:54 2014 No.6696600 >>6696531 LD 50, it's the lethal median dose.

Anonymous Tue Aug 12 09:22:49 2014 No.6696648

>>6696477
>-- I also have a question that I can't figure out:

sin(x)sin(y)+cos(x)cos(y)=cos(x+y)

(http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities))

so you're left with x+y=2k*Pi <=> y=x+2*Pi*n, n in Z.

You're right.

Anonymous Tue Aug 12 13:27:04 2014 No.6696857

If you were to choose one of these on the basis of future employment and salary, which one would you choose. Nuclear and accelerator based physics, cosmology, condensed matter physics, fluid mechanics, electronics, measurement and equipment technology and particle physics

>>	Anonymous Tue Aug 12 13:51:16 2014 No.6696887 >>6696341 It is possible http://en.wikipedia.org/wiki/Ring_species

Anonymous Tue Aug 12 14:09:46 2014 No.6696906

>>6696505
It might not be that large of a jump, but "Physics" will not get you a job unless you pursue theoretical physics, and even then, the most you're looking at is research, or possibly a consultant for a development firm.

There's lots of degrees in-between, chemistry, materials engineer, electrical engineer, etc. Basically look at anything engineering if you want a job, though there's computer-human stuff if you want to go into fields which are getting a lot of attention now (human-hardwaret interfaces, both hardware and software, "social engineering" type stuff, etc)

Anonymous Tue Aug 12 14:13:47 2014 No.6696911

>>6696857
Cosmology, condensed matter, and fluidics would have some in common, though fluidics might be more engineering oriented. The nuclear sciences would probably overlap with measurement and equipment technology, if you're going in a particle physics/chemistry direction.

We always need more chemists, the nuclear science or maintenance would be hard and possibly high paying but not common, fluid mechanics could get you almost anywhere (Petroleum, hydraulics/pneumatics, synthetics, biology, etc) but would probably require a secondary degree for best impressions.

The more mechanical fields could get you into a managerial position someday, but the research positions could make bank, though less often.

>>	Anonymous Tue Aug 12 14:15:12 2014 No.6696913 >>6696906 Oh, and physics MIGHT get you a good job, if you pair it with electrical stuff, because photonics, spintronics, etc is growing at a ridiculous pace.

>>	Anonymous Tue Aug 12 14:33:51 2014 No.6696932 >>6695842 does it matter what time of day I sleep?

Anonymous Tue Aug 12 15:05:41 2014 No.6696977

>>6696932
Depends on your melatonin cycle. MOST people have an increase starting at like 8-10PM which peaks at 2AM, and a similar increase around the same AM times, but a lower absolute value (an afternoon nap is probably a good idea based on most studies on napping and what it does). By napping it's like 2 hours at most, probably less if you get a good night's sleep.

If you want a solar cycle, those would be better times to go by, but because lolartificiallight, you could get away with a different schedule, but it would probably not be a good idea as then you're more likely to run into incompatibilities when you go outside. (light affects melatonin generation, even a low light can suppress it like 90%)

There are genetic risk of drifting, time displacement, etc for the melatonin curve. You can also take melatonin, low doses (300mcg-3mg) have been studied for inducing sleep in twenty minutes and causing the day cycle to retreat when taken two hours before bed. Little to no research has been done on larger regular doses (5mg+) and extended-release forms. Personally I've taken a shitton to sleep regularly, but I always have a time-advanced sleep cycle, mental health issues, and my "day" time shifts around if I'm not taking anything (sometimes fewer than 24 hours, usually more)

Anonymous Tue Aug 12 15:30:41 2014 No.6697030
File: 101 KB, 650x484, 137232.jpg [View same] [iqdb] [saucenao] [google]

About the FTL moving with gravity theory.
Isn't it enough to just do one of the things, pulling or pushing the ship? Every image shows both being done.
Also, how fast is that drive? Instant lightspeed or slow acceleration?

Anonymous Tue Aug 12 16:02:37 2014 No.6697076

From what I understand, the seasons are caused by the earth wobbling around as it orbits. The northern hemisphere tilts away from the sun, the southern hemisphere towards the sun and this causes winter in the north and summer in the south. Then it tilts back the other way and so on.

But my question is why does it tilt back and forth? Why doesn't it keep tilting in one direction, spinning on another axis?

On the subject of planets and astronomy, can someone help explain just why solar systems, galaxies, etc are roughly spinning along one axis? I feel like I've got a general idea but I'm not sure just how to phrase it.

>>	Anonymous Tue Aug 12 16:04:00 2014 No.6697078 >>6697030 Also, wouldnt anything in the field lose all positional awareness and just disintegrate?

>>	Anonymous Tue Aug 12 16:06:29 2014 No.6697081 >>6696977 what about in a closed system where sunlight can't get in? how would that affect your melatonin cycle?

Anonymous Tue Aug 12 16:08:42 2014 No.6697084

>>6697076
Your interpretation of seasons is wrong. The Earth is tilted, period. While on one side of the planet, one hemisphere is "straighter up" towards the sun, while the other is more "flat" towards the sun. Keeping the Earth at the same tilt, when it's on the other side of the sun, the situation is reversed.

The reason is the galaxies have rotation, and gravity pulls them down, while when they squash in the speed up and start spreading out.

Though not the most accurate by any means, you can mess with properties of a "galaxy" with:

http://synthetic-reality.com/galaxy.htm

Only in a situation with no movement would you get a universe which isn't rotating, and even then, as objects cannot be uniformly spaced in a 3d volume without it being infinite in size and mass, ANY distribution of matter will inevitably lead to some sort of disc-like object, even if 99% of the other stars are off floating loosely. The only except is a universe which is radially symmetric (such as a square) where if you took paths from the center, there would be stars on opposite sides at the same distance every time.

Anonymous Tue Aug 12 16:13:53 2014 No.6697091

>>6697030
Probably because it has to be symmetric. Whether by theory or by practical use, stuff like radio waves are always symmetric, and to non-symmetrically bend space-time, ehhhhh, you'd probably need huge amounts of real mass or negative mass to have a monopole, which is not feasible to move/make

It's faster than c, but only by fucking with things. I'm not sure how many multiples.

>>6697078
Yeah, any particle in those fields would experience huge spacetime as well as quantum fluctuations, and I think could disable the drive very easily.

>>6697081
In blinded mice, the melatonin cycle usually becomes really unstable and decays, but in humans, birth-blind and acquired blindness people still have a period, just shorter.

I think the trend in sighted people is it becomes longer, because artificial light.

>>	Anonymous Tue Aug 12 16:15:46 2014 No.6697093 >>6697091 If I close my eyes for 10 hours while still conscious, does that count as sleeping?

>>	Anonymous Tue Aug 12 16:16:49 2014 No.6697095 >>6697093 or does it produce more melatonin?

>>	Anonymous Tue Aug 12 16:18:12 2014 No.6697097 >>6697084 Sorry, that's not the galaxy simulator I was thinking of. If anyone else has seen it, it's one where you can edit the speeds, there's different initial arrangements, etc.

>>	Anonymous Tue Aug 12 16:19:27 2014 No.6697098 >>6697093 No. Sleep produces unique brain states that are not the same as when you are awake. >>6697095 It would lead to more melatonin production.

>>	Anonymous Tue Aug 12 16:29:05 2014 No.6697110 >>6697098 last questions Is it a good idea to sleep at day and be awake at night?

>>	Anonymous Tue Aug 12 16:33:08 2014 No.6697116 >>6697110 also, which body parts are not supposed to be exposed to light in producing more melatonin

>>	Anonymous Tue Aug 12 16:42:00 2014 No.6697138 >>6697084 Thank you, I understand now.

Anonymous Tue Aug 12 16:43:57 2014 No.6697143

>>6697110
No. In theory if you could filter yourself from all external light, and did your own day/light manipulation, it could work, but don't.

>>6697116
The eyes. A small amount of light suppresses melatonin production, but a sufficiently large eye mask would definitely work, closing your eyes might not that well at all.

>>	Anonymous Wed Aug 13 07:34:46 2014 No.6698137 i have one ok so we know that the real plane can be projected onto a sphere why can't the inverse operation be done?

>>	Anonymous Wed Aug 13 08:53:07 2014 No.6698226 >>6698137 cause you can't find the edges on a sphere, so you don't know where to start

Anonymous Wed Aug 13 09:57:53 2014 No.6698316

Can someone please explain the (I forget whether it's a theory or conjecture) of acceleration due to gravity?

If you have an object distance r from a point, then force of gravitation on that object is the same as if all the mass were at that point, E = 8piMG/3R I think? Can't remember exactly off the top of my head.

My main issue is in a spherical mass distribution of radius R, if you have a particle at distance r (a smaller distance than R) from the center, only the contributions from mass density in a sphere of radius r matter.

Why does the mass contribution from the mass distributed in the R - r shell not matter? Total cancellation?

>>	Anonymous Wed Aug 13 10:40:25 2014 No.6698377 Can anyone explain to me the physics behind power generation through spinning a m,gnet around a coil? >>6698316 the gravitational force gets stronger as you go closer to the source

Anonymous Wed Aug 13 15:16:48 2014 No.6698664

We all know that kinetic energy is <span class="math">\frac{m\cdot v^{2}}{2}[/spoiler].

I know many ways to show and deduce this formula and still is there a scenario where I make a mistake and don't know what it is.

Imagine you are in a train, hold a ball with mass <span class="math">m[/spoiler] and the train accelerates to velocity <span class="math">v[/spoiler] and therefore the ball has the kinetic energy <span class="math">E[/spoiler]. Now you throw the ball in the direction of <span class="math">\widehat{v}[/spoiler] with a velocity of <span class="math">v[/spoiler]. From your point of reference the ball now has kinetic energy <span class="math">E[/spoiler], you 'give' the ball <span class="math">E[/spoiler] energy. However, from an outside perspective the ball now has a speed of <span class="math">2v[/spoiler] and an energy of <span class="math">4E[/spoiler]. The latter contradicts with your reference point since the ball's kinetic energy increased by <span class="math">3E[/spoiler] instead of just <span class="math">E[/spoiler].

Where is my mistake?

>>	Anonymous Wed Aug 13 15:40:32 2014 No.6698701 >>6698664 general case is: Δ E* = Δ E + Δ P . V there is no reason for Δ E* to be equal to Δ E

>>	Anonymous Wed Aug 13 17:35:22 2014 No.6698828 Who's ready for the dumbest of dumb questions? What happens if I hit a 1 kg mass with a force of 300,000,000 N FOR 1 second?

>>	Anonymous Wed Aug 13 17:49:28 2014 No.6698845 >>6698828 you can't

>>	Anonymous Wed Aug 13 17:56:52 2014 No.6698859 >>6698828 Momentum = force * time 300,000,000N * 1s in momentum, imparted to 1kg, the 1kg will travel at 0.707c and gain a kinetic energy of 1.27 *10^19 J i may have fucked up somewhere, but i don't care.

Anonymous Wed Aug 13 18:44:41 2014 No.6698943
File: 57 KB, 750x400, SHEAFNew_Logo-750x400.png [View same] [iqdb] [saucenao] [google]

If anyone could give me a simple clear step by step example of sheafification of a presheaf I would owe you my summer. Also specifically how things are handled when you have "unwanted" "empty" patches, i.e. some disconnected cover of U over which you are trying to collate, with some Ui Uj disjoint.

Anonymous Wed Aug 13 19:29:23 2014 No.6698997

>>6698377
> We have a rotating system.
> You attach it to a permamagnet, with 2 flaps which change its polarity.
> Therefore, we have a time-dependent (oscillating) magnetic field.
> It induces an electric field.
> By Ohm's law, we have an AC in the conductor.

>>6698316
It comes from a Gauss integral. http://en.wikipedia.org/wiki/Gauss%27s_law_for_gravity..
It's completely analogue to what happens with the electrostatic electric field.

Anonymous Wed Aug 13 20:07:24 2014 No.6699043

I've been thinking of switching my major from mechanical engineering to electrical since it turns out I'm a lot better at e&m than classical mechanics. I need to repeat undergraduate first year courses if I want to do so and I'm in second year bachelors degree. Anyone gone through this hell?

>>	Anonymous Wed Aug 13 20:36:07 2014 No.6699069 >>6698845 Thanks for the well-thought-out help.

>>	JS mini-challenge Thu Aug 14 08:35:57 2014 No.6699791 >>6698943 http://math.stackexchange.com/questions/385591/question-on-sheafification-of-a-presheaf http://www.mathematik.uni-kl.de/~gathmann/class/alggeom-2002/chapter-7.pdf /sci/, provider of links instead of explanations.

Anonymous Thu Aug 14 08:43:33 2014 No.6699803
File: 41 KB, 300x445, rsd1.jpg [View same] [iqdb] [saucenao] [google]

If we've only explored "10%" of deep ocean, what do you suppose the odds are there is a significant discovery lying at the bottom of the ocean somewhere?

Significant can mean anything from the remains of an ancient city or ship, or a new species of fish or sea mammal with outstanding size, or something else anatomical.

>>	Anonymous Thu Aug 14 08:44:55 2014 No.6699805 Why do objects fall even if they have a neutral charge?

>>	JS mini-challenge Thu Aug 14 08:47:19 2014 No.6699811 >>6699805 >Why do objects fall even if they have a neutral charge? what is the meaning of this question?

>>	Anonymous Thu Aug 14 08:51:50 2014 No.6699816 >>6699811 how does gravity work? how does it attract objects without any charge also how does ground absorb current?

>>	Anonymous Thu Aug 14 10:02:02 2014 No.6699907 >>6699816 https://www.youtube.com/watch?v=jlTVIMOix3I

Anonymous Thu Aug 14 11:47:24 2014 No.6700003

>>6699816
The ground is a conductor.

charge on a spherical conductor will spread itself on the surface of the conductor, the surface of the earth.

Because adding more and more charge to the surface makes it more and more charged, there will be a voltage on the sphere.

But the voltage is so little, due to the size of the earth, compared to the static electricity on your body, the electrons find it preferable to move to lower voltage, which is the earth.

>>	Anonymous Thu Aug 14 11:48:42 2014 No.6700004 >>6700003 >The EARTH is a conductor. sorry. The Earth is slightly conductive, not enough to make wires, but conductive enough for small amount of charge redistribution.

>>	Anonymous Thu Aug 14 14:42:23 2014 No.6700164 >>6700003 >electrons find it preferable Objects have 'inclinations'? Neo-Aristotelian physics or magical world view?

Anonymous Thu Aug 14 14:56:13 2014 No.6700185

>>6695842
In a nuclear bomb, the nucleons actually decrease in mass though binding more tightly. The excess mass is released in the form of mainly gamma rays.

A helium-4 nucleus weighs less than four protons, and the difference is why the sun is hot.

Even chemical reactions work this way. N2 is lighter than two solitary N atoms...though only very, very slightly.

>>6696459
What? You included most fundamental particles in your post.
It's exactly like asking why there's so many chemical compounds and why they have such different chemistries. Combination is interesting.

>>6697084
Someone probably explained the tilt to them wrong.

Also, let me google that for them:
https://www.youtube.com/watch?v=vDgUmTq4a2Q
First result for "earth season tilt animation".

>>6699803
Practically guaranteed.

Consider how recent is the discovery of the volcanic vents and their associated life forms.

>>6699907
Nice video, if a bit slow.
The apple doesn't fall. The apple is staying still and you're accelerating upward, along with the ground.

-Clareo Nex

>>	Anonymous Thu Aug 14 16:44:52 2014 No.6700309 >>6695842 Is 2d complex vector equivalent to 4d real vector?

>>	Anonymous Thu Aug 14 16:57:57 2014 No.6700320 >>6700309 > Are 4 real numbers equivalent to 4 real numbers? ftfy

>>	Anonymous Thu Aug 14 17:02:05 2014 No.6700322 >>6700320 Now I have other question, Bloch Sphere is mainly seen as 3D sphere. But is is made with 2 different complex vector which both are taken as base. I believe it should be 4D sphere then.

Anonymous Thu Aug 14 17:07:04 2014 No.6700324

>>6700322
First of all, what you call 3D Sphere is a 2-Sphere, as it has 2 dimensions.

Then, you have 2 complex numbers represented as vectors, not 2 complex vectors, I think your misunderstanding comes from that (remember that they are 2-dimensional vectors, as their module is fixed by the sphere)

>>	Anonymous Thu Aug 14 17:07:26 2014 No.6700325 >>6696070 >Energy = Mass x c2 >matter is frozen energy Fuckin loled

Anonymous Thu Aug 14 17:35:15 2014 No.6700351

>>6700324
Now I am really confused.

My main confusion comes from that on bloch sphere I usually see, is no place where it would be the state:
<span class="math">\frac{|0\rangle+|1\rangle}{i\sqrt{2}}[/spoiler]
Neither for any of the following:
<span class="math">\frac{|0\rangle+|1\rangle}{-\sqrt{2}}[/spoiler]
<span class="math">\frac{|0\rangle+|1\rangle}{-i\sqrt{2}}[/spoiler]
<span class="math">\frac{-|0\rangle+|1\rangle}{\sqrt{2}}[/spoiler]

Only way I can explain it to myself is that bloch sphere isn't complete.

>>	Anonymous Thu Aug 14 17:40:12 2014 No.6700355 I recently saw a paper that did <span class="math"> \int_{\Omega} f \, d \Omega [/spoiler] where <span class="math"> \Omega [\math] is the sample space. This is bullshit, right?[/spoiler]

>>	Anonymous Thu Aug 14 17:43:06 2014 No.6700360 >>6700355 goof'd. Anyway, is using the set you integrate over as a measure nonsense, or is there some case when it is conceivable?

>>	Anonymous Thu Aug 14 18:06:49 2014 No.6700383 >>6700351 That's because the relation is not biyective, so there are some misrepresented points. But I'd say that that would only happen with one point, I'll check it if it ain't midnight here. Good night nigga.

>>	Anonymous Fri Aug 15 00:14:17 2014 No.6700892 File: 10 KB, 449x241, imidiot.png [View same] [iqdb] [saucenao] [google] I don't understand this step of the proof. Isn't union equivalent to OR

>>	Anonymous Fri Aug 15 01:34:34 2014 No.6700990 >>6695842 why dont we split water atoms instead of uranium atoms?

>>	Anonymous Fri Aug 15 02:38:09 2014 No.6701064 >>6700164 F =- grad(U) There is a force present, unless you oppose that force, its gonna spontaniously evolve forwards toward lower U. i'm just explaining it in a less scientific way.

>>	Anonymous Fri Aug 15 02:40:43 2014 No.6701067 >>6700892 How about if if was written like neg(x in (A U B)) neg(x in A or x in B) neg(x in A) and neg(x in B) (or is that just me applying D'morgan's law?)

>>	Anonymous Fri Aug 15 02:41:44 2014 No.6701072 >>6700990 Hydrogen and Oxygen atoms would not net energy from fission

>>	Grad U Fri Aug 15 03:34:58 2014 No.6701137 >>6701064 Is grad U a college where everyone graduates?

>>	Anonymous Fri Aug 15 03:45:12 2014 No.6701153 >>6700892 Construct a truth table for <span class="math">x\in \neg (A \cup B )[/spoiler] That line follows from that

>>	Anonymous Fri Aug 15 09:42:07 2014 No.6701527 >>6700990 water is a molecule

>>	Anonymous Fri Aug 15 09:54:59 2014 No.6701535 File: 1015 KB, 190x180, 1371684606151.gif [View same] [iqdb] [saucenao] [google] Is everything just metastable on its way to Heat Death?

Anonymous Fri Aug 15 10:28:23 2014 No.6701591

What does it mean to randomly draw values from a distribution in statistics? Say we have P(X=k), do we choose a consecutive row of numers (1, 2, ..., n), or do we pick n values from N at random and let that be our sample? In both cases, how would we determine the amount of values we need?

>>	Anonymous Fri Aug 15 10:38:07 2014 No.6701603 What is Discrete mathematics?

>>	Anonymous Fri Aug 15 10:39:26 2014 No.6701606 >>6701603 It's when you keep your voice down.

>>	Anonymous Fri Aug 15 10:45:45 2014 No.6701611 >>6701137 <span class="math"> F = - \nabla U[/spoiler]

>>	Anonymous Fri Aug 15 11:24:55 2014 No.6701635 File: 19 KB, 333x330, 1332810342064.jpg [View same] [iqdb] [saucenao] [google] How do carbon atoms form a benzene ring?

>>	Anonymous Fri Aug 15 12:06:50 2014 No.6701686 >>6701606 Not quite, if sustained for a continuous amount of time, it can still be indiscrete. People could overhear you depending on your intonation.

>>	Anonymous Fri Aug 15 15:18:01 2014 No.6701890 >>6701635 >How Elaborate what you mean by How? Rings of carbon can only be even numbered. 4 ring is too strained, 8 ring is too uncomon, 6 is just nice.

>>	Anonymous Fri Aug 15 15:21:56 2014 No.6701893 >>6701890 >Rings of carbon can only be even numbered. You wot m8? http://en.wikipedia.org/wiki/Cyclopentene

>>	Anonymous Fri Aug 15 15:25:28 2014 No.6701898 >>6701890 >4 ring is too strained and yet, it can exist http://en.wikipedia.org/wiki/Cyclobutadiene

>>	Anonymous Fri Aug 15 21:19:22 2014 No.6702339 Why does my belly button smell? Do all belly buttons smell the same? Is there any correlation between belly button stench and any other bodily properties?

>>	Anonymous Fri Aug 15 21:33:18 2014 No.6702364 >>6696911 Aren't mechanical fields already mastered? What else is there for research?

>>	Anonymous Fri Aug 15 21:44:13 2014 No.6702378 What's time? Is it an actual thing, like can it be measured, or is time the measurement itself? If no one measured anything would time stop?

>>	Anonymous Fri Aug 15 21:49:10 2014 No.6702385 How can the universe just exist? Doesn't it feel crazy to know we're real, right now?

>>	Anonymous Fri Aug 15 21:57:31 2014 No.6702398 How long, realistically, until I get robot arms? Note that I am currently unemployed.

>>	Anonymous Fri Aug 15 22:07:15 2014 No.6702426 I have an undergraduate mech eng degree. How feasible is it to get a masters in physics?

>>	Anonymous Sat Aug 16 02:05:01 2014 No.6702717 >>6701067 No, its not applying d'morgans law, you said neg(x in A) and neg(x in B) and not x in neg(A) and neg(B) If we couldnt say something that implies another thing, even if its quite direct, we couldn't do proofs

Anonymous Sat Aug 16 02:53:31 2014 No.6702778

Why do things have mass?
Why do some things not have mass?
Is it mass that causes gravity and thus attraction?
Is that why we don't have solid objects made of light?
I remember from my GCSE physics that photons did have mass, just very, very small amounts
If the faster you get to the speed of light your mass multiplies into infinity, how come light doesn't weigh infinity mass?

Yes I am high and these questions are probably dumb as fuck

Anonymous Sat Aug 16 13:54:56 2014 No.6703323

>>6702778

1. Nobody really knows.

2. "Rest" mass, not mass simpliciter. Everything has mass as everything has energy. Things with rest mass interact with the Higgs field.

3. Masses warp space. Nobody really knows why. Gravity doesn't really attract, it changes what a straight line looks like.

4. You can calculate a photon's effective mass with the mass-energy equivalence equations, given its energy. E/c^2.

5. No, way off target.
To get solidity A: things have to interact so they can stick together and B: can't have inherent velocity. (See 6.)

You can only interact with a photon by absorbing it. It's a medium of interaction, not an object to interact with.

6. Your -rest- mass multiplies. Photons have no rest mass.

F=ma. You can't accelerate something with zero mass, it makes no mathematical sense. Instead, things with no rest mass move at speed c. All such things, of which photons are only one.

Bonus:
Photons essentially don't exist in their own frame of reference. They have no mass, and exist for no time. Their universe is Lorentz-contracted to two dimensions - the direction along the photon's travel vector is lost entirely. Since interaction is limited by the principle of locality, this no-time and lost dimension also mean the photon's observable universe loses the other two space dimensions.

Which is good. If the universe existed in some sense for a photon, then the photon would have to exist for the universe, in its frame of reference, which would be a paradox.

-Clareo Nex

Anonymous Sat Aug 16 17:47:36 2014 No.6703579

If timetravel was possible, we would've already been visited by future humans. We haven't yet, so this implies either:

1) Timetravel is impossible
2) Our time isn't interesting enough
3) It's been kept a secret
4) Mankind dies before advancing far enough to travel back in time

1, 2 and 3 all don't seem to work for me, leaving only 4. Considering the speed at which our technology improves, we should be able to travel in time in 300 years max. So, will we die before we reach the year 2300?

>>	Anonymous Sat Aug 16 17:52:49 2014 No.6703583 <span class="math">\displaystyle{ E^2 = p^2c^2 + m_0^2c^2 }[/spoiler] If I remember correctly

>>	Anonymous Sat Aug 16 17:54:17 2014 No.6703585 >>6703583 Actually, my bad, I believe it is c^4 so <span class="math"> \displaystyle{ E^2 = p^2c^2 + m_0^2c^4 } [/spoiler]

>>	Anonymous Sat Aug 16 18:34:17 2014 No.6703618 >>6696341 zeroth law of anonspecies

>>	Anonymous Sat Aug 16 18:35:18 2014 No.6703620 >>6696341 Well species are slightly ambiguous so there can be fuzziness and overlapping. Think of it as a Venn Diagram with 3 circles. A circle in the middle intersects with the two circles on the sides

>>	Anonymous Sat Aug 16 19:07:12 2014 No.6703654 >>6696437 do you understand what the symbol "abs" means?

>>	Anonymous Sat Aug 16 21:53:05 2014 No.6703857 Would it be possible to build a disc with a 299 792 kilometer circumference and spin it with a gear system to make the rim approach the speed of light?

>>	Anonymous Sat Aug 16 22:45:01 2014 No.6703924 >>6703857 no. The outer part of the disc would "realize" that it should spin at the speed of sound. Plus the energy required to spin the disc would approach infinity the more it is gaining torque.

Anonymous Sat Aug 16 22:55:21 2014 No.6703937

Should I use a dictaphone in lectures to help when reviewing my notes?

I've managed to retain knowledge throughout my first year, but I've noticed that most of my notes taken in specific classes make little sense as I was just copying down whatever went on the board, but in those classes my lecturers simply recited information and used the boards only for examples.

I've read online about some experiences where lecturers got pissy about ditctaphones. Do they really get upset about dictaphones?

>>	Anonymous Sat Aug 16 23:02:47 2014 No.6703949 Prove it with Venn's diagrams.

>>	Anonymous Sat Aug 16 23:08:37 2014 No.6703953 Picture explanation of how <span class="math">y(x)=Acos(cx)+Bsin(cx)[/spoiler] becomes <span class="math">y(x)=Dsin(cx+r)[/spoiler] please?

Anonymous Sat Aug 16 23:11:40 2014 No.6703956

>>6697030
You're not moving the ship, you're moving the space containing the ship. The force applied to just push or pull the ship would probably tear it apart and probably kill anyone inside to accelerate to ftl within any useful timetable, whereas moving the space around the ship shouldn't cause acceleration within the bubble.

>>	Anonymous Sat Aug 16 23:23:21 2014 No.6703969 >>6703924 Sounds fucky So it would deform into a spiral shape?

Anonymous Sat Aug 16 23:25:57 2014 No.6703978

>Nice video, if a bit slow.
>The apple doesn't fall. The apple is staying still and you're accelerating upward, along with the ground.
>-Clareo Nex
What do you mean? Are you talking about the expansion of spacetime? If so, does that mean particles and matter are also expanding?

>>	Anonymous Sat Aug 16 23:29:56 2014 No.6703988 >>6703978 Meant to quote: >>6700185 Also had sage on. Stupid mobile app. Stupid me.

>>	Anonymous Sun Aug 17 06:42:11 2014 No.6704469 >>6703953 Apply Fourier transform. You got spikes at the same places, adjust their height by playing with A,B,D

Anonymous Sun Aug 17 10:30:16 2014 No.6704698

The following problem can be solved either the easy way or the hard way.
Two trains 200 miles apart are moving toward each other; each one is going at a speed of 50 miles per hour. A fly starting on the front of one of them flies back and forth between them at a rate of 75 miles per hour. It does this until the trains collide and crush the fly to death. What is the total distance the fly has flown?
The fly actually hits each train an infinite number of times before it gets crushed, and one could solve the problem the hard way with pencil and paper by summing an infinite series of distances. The easy way is as follows: Since the trains are 200 miles apart and each train is going 50 miles an hour, it takes 2 hours for the trains to collide. Therefore the fly was flying for two hours. Since the fly was flying at a rate of 75 miles per hour, the fly must have flown 150 miles. That's all there is to it.
When this problem was posed to John von Neumann, he immediately replied, "150 miles."
"It is very strange," said the poser, "but nearly everyone tries to sum the infinite series."
"What do you mean, strange?" asked Von Neumann. "That's how I did it!"

I came across this anecdote but I'm not a mathematician. I do know what infinite series are but I can't find the way to construct the one needed for this problem. Help?

Anonymous Sun Aug 17 10:40:12 2014 No.6704714

If I apply Fourier Transform to the RHS of the first equation I end up with <span class="math">i \sqrt{pi/2}A \delta( \omega-c)-i \sqrt{pi/2}A \delta( \omega+c)+ \sqrt{pi/2}B \delta( \omega-c)+ \sqrt{pi/2}B \delta( \omega+c)[/spoiler]
Too bored to type \frac to all of these so whatever. What am I supposed to do with this?

>>	Anonymous Sun Aug 17 10:49:38 2014 No.6704725 >>6704714 >>6704469 meant to quote this.

Anonymous Sun Aug 17 10:50:52 2014 No.6704726

>>6696857
>condensed matter
It's the most active field of physics. Loads of theoretical work to be done and jobs in academia, as well as vast applications in industry.
If you are interested in the academic side, the stuff you get to work with is awesome. You can use QFTs that particle physicists ignore because they break down at very small scales. You only care about roughly the scale of crystal lattice spacing, so you can use all of these strange theories forbidden by the particle guys. Your work is also (likely) non-relativistic, which open even more options, because your theories don't need to be Lorentz invariant!
Note: I am a math, so this is unbiased.

>>	Anonymous Sun Aug 17 10:53:52 2014 No.6704730 >>6703857 http://en.wikipedia.org/wiki/Ehrenfest_paradox

>>	Anonymous Sun Aug 17 11:39:08 2014 No.6704785 >>6704714 make it real part = to the real part of the second equation. D,r are free parameters

Anonymous Sun Aug 17 12:24:13 2014 No.6704857

>>6703978

General relativity is weird.

It's not the expansion of spacetime. A little jargon: spacetime is 4-space and without time it's 3-space; 3-space is a special case of 4-space. (Caveats apply; not relevant here.)

The expansion is expansion of 3-space.

The ground, and you, need to accelerate upward in 4-space to stay in the same place in 3-space. 3-space is more intuitive but acceleration is all relative to 4-space. The pressure you feel from the ground is causing the acceleration. When you drop the apple, it feels no pressure; it's in free-fall. Free-fall in 3-space is what a straight line looks like in 4-space.

If this is hard to understand...sorry. GR is weird. It does make it seem like everything is growing relative to 4-space, since the entire surface of a planet is accelerating outward. I'm fairly sure that's not the case but I'm also fairly sure I can't explain why.

Anonymous Sun Aug 17 12:34:19 2014 No.6704875

>>6702378

Nobody really knows. Don't let them fool you into thinking they do.

Measuring time is easy. No more difficult than measuring distance, mass, velocity, etc... In general, physicists measure things by finding an equation involving it and knowing all the other variables, then solving for the last variable. Time shows up in equations, so measuring it is just a matter of using one of them.

Thing is, asking what is time is the same as asking what is space, what is energy, yet nobody asks the latter two.

D = vt, which means t = D/v. Thing is, you have to measure D and v. First you need an equation that has D but not t. Measuring sticks essentially work by D2 = D1, so that's easy.

But what is distance?

Every interaction is informally a measurement; it's impossible to rigorously conceive of stopping all measurement.

Anyway, let me try to fool you into thinking I know what time is.

Time is the independent variable. For various reasons, physics must be composed of functions. To mathematically qualify as a function, you need an independent variable - colloquially the vertical line test - for which the function has a unique output for every valid input.

In physics, this variable is time.

-Clareo Nex

Anonymous Sun Aug 17 12:43:22 2014 No.6704886

>>6704857
I'm trying to figure out why mass warps spacetime without really understanding a whole lot about the underlying principals. Intuitively, it would seem like inertia has a lot to do with gravitation, as in, since everything in space is in motion, it has gravity, and since objects with more mass have more inertia given the same speed, their gravity is higher. I feel like it's related somehow, but it's hard for someone like me to pinpoint how.

Anonymous Sun Aug 17 14:40:02 2014 No.6705021

>>6704886

Ref:
>>6703323
>3. Masses warp space. Nobody really knows why.

For example it might be because masses are woven space. But nobody really knows what mass is either.

There was a good magazine article on the particles-as-knots idea, but I seem to have lost the link. Had pictures and stuff.

Physics will eventually get to a point where there is no explanation. The ultimate fundamentals will be true because they're true, not because of underlying principles. Might as well get used to it now.

-Clareo Nex

>>	Anonymous Sun Aug 17 15:30:25 2014 No.6705080 Is it possible for a thing, which is more satisfying for a penis, than vagina, to exist? On the one hand because of evolution vagina should be the best penis container feeling-wise, but who knows...

>>	Anonymous Sun Aug 17 18:20:24 2014 No.6705337 bump please

>>	Anonymous Sun Aug 17 18:37:17 2014 No.6705360 Is there anything that the Bohr model of the atom can't explain, but orbitals can?

>>	Anonymous Sun Aug 17 18:39:19 2014 No.6705364 Should I study Nanotechnology or Electrical Engineering?

Anonymous Sun Aug 17 18:44:53 2014 No.6705372

Hey /sci/ I'm a HS student, gonna start my last year soon, and I want to become a physicist. I've been quite a lazy fag up until last year, when I realised that the glory days are gone, and I suck at math (I was still top of my class, in a good school, but sometimes had problems with really basic shit because of my ignorance), so I carefully read all four math textbooks, did all the exercises, and this significantly improved my math skills, so now I'm thinking of reading a book about calculus, and I'd like to know which one should I read, Spivak's or Stewart's (the sticky says Spivak's is more rigorous).

Anonymous Sun Aug 17 18:56:27 2014 No.6705381
File: 50 KB, 470x265, yfw lhc discovers only the higgs.jpg [View same] [iqdb] [saucenao] [google]

>>6705372
>the glory days are gone
This. Physics is dead. Become a biologist (a parrot). You don't need math unless you want to become a quant and exploit the proletariat. For that you'll need a PhD in triple integrals or higher.

>>	Anonymous Sun Aug 17 19:02:46 2014 No.6705389 >>6705381 I meant my glory days, when I didn't learn shit (cause I was a lil prick) and was still good at math. >Become a biologist I don't want to. The things I'm interested in are computers and physics, and I'm more interested in physics.

>>	Anonymous Sun Aug 17 19:21:07 2014 No.6705411 >>6705389 >my glory days >I'm a HS student Are you a 200 year old loli schoolgrill?

>>	Anonymous Sun Aug 17 23:13:43 2014 No.6705664 File: 44 KB, 417x422, 1351988036719.jpg [View same] [iqdb] [saucenao] [google] What does the M in M-theory stand for?

>>	Anonymous Sun Aug 17 23:15:02 2014 No.6705666 >>6705664 Mom as in your mom

>>	Anonymous Sun Aug 17 23:16:09 2014 No.6705669 >>6705664 Membrane or moe, I can't remember.

>>	Anonymous Sun Aug 17 23:17:52 2014 No.6705673 If alternate universes exist within millimeters from us, why cant i reach out and touch them inb4 >muh dimensions

>>	Anonymous Sun Aug 17 23:18:29 2014 No.6705674 File: 5 KB, 500x169, mysterious figure.gif [View same] [iqdb] [saucenao] [google] >>6705664 >the only correct answar

>>	Anonymous Mon Aug 18 01:54:05 2014 No.6705846 File: 499 KB, 1280x720, string theory.webm [View same] [iqdb] [saucenao] [google] >>6705669 definitely moe

>>	Anonymous Mon Aug 18 05:05:31 2014 No.6706004 >>6705381 >>6705411 Sorry man I was just exaggerating for fun, I do realise that it might have sounded a bit autistic. English is not my native language, and I wrote it at 1 a.m. (not like it's that late or something, but I was pretty fucking tired).

>>	Anonymous Mon Aug 18 23:54:05 2014 No.6707437 How do I take a device that transmits in the SHF range at 24.15GHz and boost the frequency so that it transmits at any frequency between 57-64GHz in the EHF range which I believe I am allowed to use without a license from the FCC?

>>	Anonymous Tue Aug 19 00:27:49 2014 No.6707481 >>6695842 Can science invent magic?

>>	Anonymous Tue Aug 19 00:36:23 2014 No.6707495 >>6705846 so moe~

>>	Anonymous Tue Aug 19 05:32:09 2014 No.6707759 If you connect the negative end of a battery directly and only to ground, will it drain the battery? I guess the same result would happen if it was the positive end that is connected to ground >>6707481 Depends on the definition of "magic"

>>	Clareo Nex Tue Aug 19 08:21:27 2014 No.6707890 >>6707481 No. There's simply no room in the laws of physics for such things. They're woven together perfectly. That very perfection is a bit magic, though.

Anonymous Tue Aug 19 10:12:09 2014 No.6708012 [DELETED]

>>6695842
I'm rehearsing my high school maths. I'm currently doing limit problems, and I forgot how to do ones like these:

<span class="math">\lim_{x \to 3}\fraq{\sqrt{x+6}-\sqrt{3x}}{\sqrt{x-3}}[/spoiler] for x > 3

My intuition tells me to make the numerator rational and/or to factor out an x, but I keep getting an undetermined result when I plug in 3

Anonymous Tue Aug 19 10:18:54 2014 No.6708017 [DELETED]

>>6708012
I'm rehearsing my high school maths. I'm currently doing limit problems, and I forgot how to do ones like these:

<span class="math">\lim_{x\rightarrow 3} \frac{\sqrt{x+6}-\sqrt{3x}}{\sqrt(x-3}}[/spoiler] for x > 3

My intuition tells me to make the numerator rational and/or to factor out an x, but I keep getting an undetermined result when I plug in 3

Anonymous Tue Aug 19 10:30:22 2014 No.6708029

>>6708017
>>6708012
I'm rehearsing my high school maths. I'm currently doing limit problems, and I forgot how to do ones like these:

lim sqrt{x-6}-sqrt{3x} / sqrt(x-3}
x->3
>

My intuition tells me to make the numerator rational and/or to factor out an x, but I keep getting an undetermined result when I plug in 3

Sorry for the reposts, but I have no idea why my LaTeX isn't working today

Anonymous Tue Aug 19 10:34:00 2014 No.6708033

>>6708012
>>6708017
>>6708029
http://www.codecogs.com/latex/eqneditor.php
Use it to test your latex code before posting it. You can delete your unnecessary posts by ticking the checkbox next to them then clicking delete at the bottom of the page.
<span class="math">\lim_{x\rightarrow 3} {\frac{\sqrt{x+6}-\sqrt{3x}}{\sqrt{x-3}}}[/spoiler]

>>	Anonymous Tue Aug 19 10:42:01 2014 No.6708049 >>6708033 Thanks man

Anonymous Tue Aug 19 10:50:27 2014 No.6708061

>>6708029
>>6708033

Sub in the limit, if you get an appropriate answer than you are good.

If you get x/0 (where x is a real number) then the answer is undefined.

If you get 0/0 then differentiate top and bottom and then start the list again (sub in, if you get 0/0, differentiate again).

or shit method complete the square on the top: (a+b)(a-b) = a^2+b^2

>>	Anonymous Tue Aug 19 10:53:15 2014 No.6708067 >>6708029 >high school maths >limits I didn't learn calculus until I was 20 =(

>>	Anonymous Tue Aug 19 10:54:37 2014 No.6708069 What the fuck does >key performance indicators - theoretical considerations and empirical evidence mean? It's so fucking vague I have no idea what to do.

Anonymous Tue Aug 19 11:30:20 2014 No.6708124

>>6708061
Thank you for the post. I used Wolfram Alpha and apparently there is no real limit, not even one-sided ones. My textbook's wrong, and I've caught mistakes in it earlier.

>>6708067
Hey, don't feel too bad, I hardly knew what a vector was when I enrolled in engineering. I do count myself very lucky, though, since quality education is quite affordable in my country. I do think that American education will become better, since politicians can't ignore the lowering scores anymore.

Anonymous Tue Aug 19 13:15:19 2014 No.6708238

>>6695842

Retarded question I've always been embarrassed to ask.

If space is a vacuum, then why is it so hard to reach high speeds in space? Say you're traveling at 100mph in space with nothing to slow you down. Wouldn't even a small combustion cause you to go faster? And if so, why not just continue it until you reach the speed of light?

And if that wasn't stupid enough, would using a nuclear explosion to propel an object in space cause it to destroy that object? If theres no force acting on the object except the nuclear blast, wouldn't the blast just act unhindered and cause the object to propel?

>>	Anonymous Tue Aug 19 13:43:59 2014 No.6708275 >>6696070 i think you're totally right but you should say compressed rather than frozen, "frozen energy" sounds scary and i don't think freezing energy is possible

Anonymous Tue Aug 19 14:52:30 2014 No.6708381

>>6708238
Inertia (mass×velocity).
The inertia of a closed system can't change (just think about it; why would it?). This means that if you were in space, perfectly still, and you'd kick away a nearby rock, it would now have -1×your inertia, so the sum off all the inertia in the system wouldn't change. This is just like how rockets propel themselves: they push the exhaust in the opposite direction, and they get the energy to push it away by burning the fuel.
Imagine you are in space, and you have a bunch of small rocks in a bag. You throw them away, one-by-one, at the same speed relative to you. The rocks you throw away increase your inertia by the same amount, but speed=inertia/mass, and you have more mass at the beginning (you have a bag full of rocks, while by the end you've thrown away most of them), so each rock increases your speed by a little bit more than the last one. The thing is, you could calculate how many times as fast as the rocks you throw away you'll be from the mass and the number of rocks. Of course, rocks are discrete objects, while the jets coming from the rockets are continuous streams of particles, but that's like having a lot of infinitesimally small rocks.
As I've said, it can be calculated how many times faster you'll be than the exhaust, and to be twice as fast, about 7/8 of the rocket's initial mass would have to be fuel. To be four times as fast, about 98.15% of the rocket would have to be fuel. And the exhaust's speed is not even comparable to that of light, you'd have to go thousands of times faster than the exhaust to achieve speeds comparable to it, which means that more than 99.9999999% (wolframalpha couldn't really calculate it) of the rocket would have to be fuel, that's why you might have heard things like "to accelerate a rocket to 90% of the speed of light, you'd need more fuel than the amount of matter in the universe".
http://www.wolframalpha.com/input/?i=rocket+equation

>>	Anonymous Tue Aug 19 19:37:47 2014 No.6708826 >>6708381 Sorry for the delayed response. Great explanation, thanks!

>>	Anonymous Wed Aug 20 00:12:48 2014 No.6709220 >>6707890 You don't even know what the laws are.

Anonymous Wed Aug 20 00:29:40 2014 No.6709260

Maybe this isn't as stupid but I don't want to make a new thread.

Say you have an unknown function with known y values corresponding to known x values. How would you be able to find an approximate volume when this function is rotated around the x axis using trapezoidal approximation? Are you supposed to find the linear functions associated with each trapezoid and rotate those? Because that's a lot of effort.

>>	Anonymous Wed Aug 20 00:45:50 2014 No.6709284 >>6703654 He doesn't lift.

>>	Anonymous Wed Aug 20 01:10:58 2014 No.6709322 pls respond >>6707759

>>	Anonymous Wed Aug 20 04:30:21 2014 No.6709559 >>6708067 In greece I learnt up to integration by parts and trig substitution(calc2) and ODEs

>>	Anonymous Wed Aug 20 04:32:25 2014 No.6709560 >>6709559 All in HS. And I was tested for them in finals.

>>	Anonymous Wed Aug 20 05:16:50 2014 No.6709600 can someone explain to me why temperature remains constant as a substance changes phase as energy input is increased??

>>	Anonymous Wed Aug 20 05:45:30 2014 No.6709624 >>6707759 >>6709322 No, it won't. If it would drain the battery then all those electrons would go away, but they are needed for the chemical reaction in the battery.

>>	Anonymous Wed Aug 20 05:51:55 2014 No.6709631 >>6709624 > but they are needed for the chemical reaction in the battery. please elaborate

Anonymous Wed Aug 20 06:06:45 2014 No.6709652

If two independent variables, v1 and v2, have their own poisson-distributions with averages u1 and u2, and i want to know something about the product, v1*v2, I can simply calculate a new distribution with average u1*u2 and work with that, right?

I haven't done statistics in forever

Anonymous Wed Aug 20 06:40:57 2014 No.6709669
File: 48 KB, 727x422, Galvanic_cell_with_no_cation_flow.png [View same] [iqdb] [saucenao] [google]

>>6709631
In chemical reactions you usually end up with the same things you had at the beginning, just in different forms (like burning hydrogen to make water), cause particles don't just fly away into the void.
On pic related Zinc dissolves into the electrolyte, and then copper is deposited on the copper electrode, but for that reaction to take place, you need to "transport" those two electrons to the copper electrode. If you just "took away" the electrons, you'd end up with more and more zinc ions, so it would become more and more positively charged, and taking away negative charges from something positively charged requires energy (just like pulling away a magnet from another), so it wouldn't occur "naturally".
Sorry for the shitty explanation, I suck at chemistry.

>>	Anonymous Wed Aug 20 07:57:38 2014 No.6709745 Is there a process to extract sulfur from plastic? I looked it up on google but can't seem to find anything. Isn't it strange that the idea of recycling chemicals from waste doesn't get discussed very much

Anonymous Wed Aug 20 08:19:57 2014 No.6709762

>>6709745
In recycling, cost is king. Things like plastics and paper are stupid to recycle, the pollution caused by transporting, and recycling completely outweigh the benefit of less waste and that's why you pay the council to recycle instead of them paying you, such as things worth recycling (steel, aluminium, gold).

If sulfur become scarce enough, it will be recycled. If you find a really cheap and efficient way of recycling it, you will not only help the environment, but also get rich doing it.

>>	Caroline !cJzfHn8Wko Wed Aug 20 08:25:55 2014 No.6709765 >>6709600 Because God is love. >>6709652 You don't need statistics when you have God as your guide. >>6709745 It will change when you love it enough.

>>	Anonymous Wed Aug 20 08:39:31 2014 No.6709785 why does the electric field get stronger as current increases?

Anonymous Wed Aug 20 08:44:34 2014 No.6709792
File: 52 KB, 250x968, oude geuze.jpg [View same] [iqdb] [saucenao] [google]

How do I calculate the time needed for beer in a glass bottle to reach perfect serving temperature of 12°C, if I take it out of the fridge at it's current temperature which is 4°C? (Room temp is 25°C).

>>	Anonymous Wed Aug 20 08:52:49 2014 No.6709801 >>6709792 Ever heard of CLOCKS?

>>	Anonymous Wed Aug 20 08:53:31 2014 No.6709803 What happens--in an atomic scale--if electrical current increases or decreases? Also, how do ultracapacitors work?

>>	Anonymous Wed Aug 20 08:58:55 2014 No.6709805 >>6709792 I need an equation that will tell me how much time it will take to get to 12°C.

>>	Anonymous Wed Aug 20 08:59:57 2014 No.6709806 >>6709805 Fuck, meant to quote >>6709801

>>	Anonymous Wed Aug 20 09:28:18 2014 No.6709829 >>6709806 <span class="math">dT/dt=k(T_t-T_s)[/spoiler]. Here is your equation.

>>	Anonymous Wed Aug 20 09:37:04 2014 No.6709844 >>6709829 In case you're an engineer, here's the solution, let me make you suck one dick less for an answer(who am I kidding, this will never happen) <span class="math">T(t)=T_s+(T_0-T_s) e^{-kt}[/spoiler] solve for the variable you need.

>>	Anonymous Wed Aug 20 09:38:48 2014 No.6709850 File: 963 KB, 268x205, 1406088476971.gif [View same] [iqdb] [saucenao] [google] I have two 3D vectors that share a common starting point (not at the origin!). How do I calculate the angle between these two vectors?

>>	Anonymous Wed Aug 20 09:50:59 2014 No.6709871 >>6709829 How do I plug this shit in? I assume that T0 = initial temp, Ts = surrounding temp, and k being the thermal conductivity of glass, correct?

>>	Anonymous Wed Aug 20 09:53:13 2014 No.6709875 >>6709850 <span class="math">\theta = arccos \frac{ \vec{A} \cdot \vec{B}}{\| \vec{A}\| \| \vec{B}\|}[/spoiler]

>>	Anonymous Wed Aug 20 09:56:21 2014 No.6709880 >>6709871 Did you seriously consider direct substitution in a differential equation? You're underage, you shouldn't drink.

>>	Anonymous Wed Aug 20 09:57:56 2014 No.6709881 >>6709875 But that formula implies that they're both starting at the origin, which is not the case.

>>	Anonymous Wed Aug 20 09:58:18 2014 No.6709882 >>6709871 This is a board with latex. If someone spends time to answer your question in latex, you should spend time responding in latex too.

>>	Anonymous Wed Aug 20 10:00:13 2014 No.6709884 >>6709881 it doesn't matter where they start because each vector can be translated without changing it's direction or intensity

>>	Anonymous Wed Aug 20 10:04:11 2014 No.6709889 >>6709881 If it makes you feel any better, translate them to the origin and apply the formula given.

Anonymous Wed Aug 20 10:05:37 2014 No.6709890

>>6709600
The energy goes into breaking bonds instead of increasing average molecule speed.

>>6709792
>>6709829
>>6709844
Though it's of limited use since you need to know the heat conduction properties of the bottle to calculate k, or else find it empirically. Formally known as Newton's law of cooling.

>>6709803
1. Look up how much of a Coulomb one electron is. Find your current in Coulombs. Divide; that's how many electrons are crossing a perpendicular surface per second. In practice it's all electrons on the surface of the wire unless it runs out of conductive electrons, then the current starts migrating inward and wire resistant jumps. The latter is only important for very small wires, such as internal CPU connections.

2. According to wikipedia it's the halfway point between a battery and a capacitor. I don't mind dumb questions but at least avoid www.lmgtfy.com.

>>	Anonymous Wed Aug 20 10:12:24 2014 No.6709895 >>6709890 >The energy goes into breaking bonds instead of increasing average molecule speed. but why is that?

>>	Anonymous Wed Aug 20 10:16:58 2014 No.6709901 >>6709880 I've only dabbled with maths and physics in high school and have no formal education beyond that, so I've pretty much forgotten everything relating to said subjects. >>6709882 Sorry, I'm unfamiliar with latex.

>>	Anonymous Wed Aug 20 10:21:26 2014 No.6709904 >>6709884 I assume he's talking about two vectors that specific end points, in which case their starting point would matter. Can't remember the maths though.

Anonymous Wed Aug 20 10:26:25 2014 No.6709907

>>6709904
if he knows only the end points and not the origin there are an infinite amount of shared origins so he can't answer the question

if he knows the origin and end points than he can position the vectors exactly in space as a linear combination of unit vectors i,j and k and he can use the formula without worrying

>>	Anonymous Wed Aug 20 12:23:35 2014 No.6710048 >>6709652 anyone?

Anonymous Wed Aug 20 15:57:08 2014 No.6710344

>>6709895
It's not really a why, it's an identity. To put energy into breaking bonds is what it means to change phase.
Perhaps go at this from another angle. To oversimplify a solid atom has a top speed it can vibrate at before it flings itself out of the crystal lattice. In macrophysics, the rest of the sample then acts as a heat sink - you can try to heat that liquid molecule, but it will run into the solid and dump its energy into breaking a bond, and this continues until more or less all of the block melts.

Anonymous Wed Aug 20 17:18:15 2014 No.6710530
File: 4 KB, 154x269, 1408397107924.png [View same] [iqdb] [saucenao] [google]

>>6695842
What's a field, and where are the values of each point in field stored?

I mean, since there are infinite points in the fields why couldn't you utilize one (say electromagnetic) and build an infinite storage?

>>	Anonymous Wed Aug 20 17:19:38 2014 No.6710535 >>6710530 >infinite points in the field read QFT

>>	Anonymous Wed Aug 20 18:57:09 2014 No.6710706 How can one tell the difference between being bad at math and lacking mathematical foundations?

>>	Anonymous Wed Aug 20 22:47:42 2014 No.6711103 >>6695842 Will there be scientific research in heaven?

>>	Anonymous Wed Aug 20 23:08:05 2014 No.6711133 Does gravity effect magnetism and vice versa?

>>	Anonymous Wed Aug 20 23:29:06 2014 No.6711163 >>6710706 If you are unable to learn the foundations.

>>	Anonymous Wed Aug 20 23:31:22 2014 No.6711175 >>6711103 >No Proof heaven is a shitty place. Checkmate religio-fags.

>>	Anonymous Wed Aug 20 23:32:51 2014 No.6711177 >>6711175 But if there is no science or mathematics then how can you rigorously prove that there?

Anonymous Wed Aug 20 23:37:43 2014 No.6711184

>>6710706
There's a paper I can't find for you, but it outlines dissociations in dyscalculia.

>hard logic
>this is that for some reason
>these things are true
>A defines B therefore A

>generalities
>this is about that
>yeah I get what you mean
>I understand, I don't need to follow all the steps

Some people are bad at math because they can't remember large amounts of "fixed" information like the times tables. Nearly every burgerlander is bad because they can't associate multiplicative-relativeness/fractional-parts at the same time when doing fractions.

Generally if you can get to division you'll be good at the 'hard logic' parts, and if you can get through algebraic manipulation (quickly and accurately) you can deal with the squishier parts. I'm a tutor, and I've had to deal with people who could get straight A's with no number sense, but they'd put in hours of work. FYI, most people put in hours of work and don't have a good number sense if they want to pull As.

Anonymous Wed Aug 20 23:54:23 2014 No.6711208

On relativity: Say a rocket carrying passenger John was travelling from star A to star B. Star B is 10 lightyears away from Star A. There are observers on star A. If John is travelling at .5*c, how long does it take for him to reach star B from 1) his perspective, 2) others' perspectives

>>	Anonymous Wed Aug 20 23:55:25 2014 No.6711210 >>6711208 i.e., does it take him less than 20 years from his perspective, more than 20 years from others' perspectives, both?

>>	Anonymous Wed Aug 20 23:55:36 2014 No.6711211 What's a good highschool physics textbook for a person who's only interested in the applying it? I was looking through the Feynman Lectures and it seemed like it was aimed at aspiring physicists.

pleb-o-matic Thu Aug 21 01:04:56 2014 No.6711308

>>6703579
yes and no. The limits of time travel is nonexistent yet before the point future time travelling is possible to reach us at our present. It is also possible there was a huge flaw when developing time travel - a paradox or shift in living conditions - or the future is just too much damn fun.

>>	Anonymous Thu Aug 21 01:07:10 2014 No.6711311 >>6711211 So basically you want a calculus based physics book that isn't too hardcore? University Physics by Young and Freedman.

Anonymous Thu Aug 21 01:15:55 2014 No.6711328

>>6711208
From his perspective it takes 20 years
From observers on star a it takes 30 years

I don't study or keep up with any of this, I just made that up. But 10 lightyears to travel at half the speed of light means it takes 20 years to get there, and from the second he gets there that light will take an additional 10 years to get back to star a, so they won't see John arriving at star b for 30 years.

Right?

>>	Anonymous Thu Aug 21 01:18:01 2014 No.6711334 >>6711328 no

Anonymous Thu Aug 21 05:24:45 2014 No.6711532

>>6704698
>>6704698
200 miles @ (50 + 75) mph = 1.6 h
fly 1.6 * 75 mph = 120 miles
trains 1.6 * (50 + 50) mph = 160 miles

40 miles remaining @ (50 + 75) mph = 0.32 h
fly 0.32 * 75 mph = 24 miles
trains 0.32 * (50 + 50) mph = 32 miles

8 miles remaining ...

Anonymous Thu Aug 21 06:57:04 2014 No.6711597

I have free access to the Nature journal via institution.

Is it possible to download complete issues?

I don't like the online reading experience. Article titles don't give much information and it's annoying to download them all. I'd much rather have a 100 site PDF to comfortably scroll through. Alternatively I can get physical versions of the journal from friends but I'd prefer a PDF version for my tablet.

>>	Anonymous Thu Aug 21 10:10:26 2014 No.6711718 >>6711532 With your explanation I found this sum; <span class="math">\sum_{i=1}^{\infty} \frac{1000}{5^i}[/spoiler]

>>	Anonymous Thu Aug 21 10:12:17 2014 No.6711721 >>6711718 or <span class="math">\sum_{i=0}^{\infty} \frac {200}{5^i}[/spoiler]

>>	Anonymous Thu Aug 21 10:17:45 2014 No.6711726 >>6704698 Ez way: Time until trains collide: 2h. Distance flied in this time: 2h*75 mph=150 miles.

>>	Anonymous Thu Aug 21 10:23:30 2014 No.6711732 >>6711328 No it's not that simple. Relativity fucks some of it up, I just don't know which way it fucks.

Anonymous Thu Aug 21 10:41:04 2014 No.6711748

>>6704698
I'm completely sleep deprived and too tired to think right now so I'll probably be wrong. That said, I will use meters per second instead of miles per hour because fuck you and your inferior unit system.

Initial condition: fly and train are apart by 200m, they approach each other with a speed of 125m/s. This means that they will meet after 1.6s. The new distance between the trains is 40m. Here you see the pattern: the distance declines by the factor 5 each time.

Initial distance the fly flew was 120m. Total distance therefore is:
<span class="math">120m\cdot \sum_{n=0}^{infinity} \frac{1}{5^{n}} = 120m\cdot 1.25 = 150m[/spoiler]

Do you have the solution somewherer? Is 150m correcet? Fucking headache how do I make infinity in latex? I don't know why I forgot it now of all times. Is probably the sleeping pill, I am really sorry...

>>	Anonymous Thu Aug 21 10:50:56 2014 No.6711756 >>6711748 \infty and yes it's 150

Anonymous Thu Aug 21 11:30:42 2014 No.6711818
File: 482 KB, 500x280, okabe.gif [View same] [iqdb] [saucenao] [google]

How realistic and scientifically plausible is the time travel science presented in Steins;Gate. I'm guessing there is fiction in there but which elements are routed in real science? Pls elaborate

>>	Anonymous Thu Aug 21 11:44:18 2014 No.6711839 File: 111 KB, 267x200, well i have no idea.gif [View same] [iqdb] [saucenao] [google] What does the "a" coefficient do in a Cubic polynomial in the form of y= a(x-a)(x-β)(x-γ)?

Anonymous Thu Aug 21 12:20:08 2014 No.6711876

>>6711839
Never mind guys
You're 2 slow 4 me
/b/ helped me out and said that the "a" coefficient determines how "stretched" the function is vertically as with accordance to whether or not the polynomial has a Local maximum or minimum value
Step it up /sci/

>>	Anonymous Thu Aug 21 15:36:19 2014 No.6712129 What is the most complex branch of science that requires extremely high IQ to comprehend? >inb4 quantum physics >inb4 special/general relativity Be specific..

>>	Anonymous Thu Aug 21 15:42:04 2014 No.6712136 I want to learn Organic Chemistry because i'm bored. Where should I start?

Anonymous Thu Aug 21 15:43:10 2014 No.6712137

Can anyone think of a continuous function <span class="math">f(x)[/spoiler] with the real numbers as it's domain, that has the following property?
<div class="math">
\displaystyle \forall x \in \mathbb{R}\,\left(f(x) \ne x \right)
</div>

In other words, a function which does not coincide with the line <span class="math">y = x[/spoiler].
Only other stipulation is that it can't be something like
<span class="math">
\displaystyle f(x) = x + 1
[/spoiler]
or
<span class="math">
\displaystyle f(x) = |x - 2|
[/spoiler]
where it's just line(s) that are parallel and so don't coincide.

>>	Anonymous Thu Aug 21 15:44:38 2014 No.6712141 >>6712137 Forgot to add: Or sketch out an explanation of why one doesn't exist as I'm starting to suspect that may be the case, but can't figure out why it would be.

>>	Anonymous Thu Aug 21 15:48:27 2014 No.6712146 >>6709260 pls respond

>>	Anonymous Thu Aug 21 15:50:43 2014 No.6712149 >>6712137 >>6712141 shit I just realized how hugely I was overthinking this <span class="math"> f(x) = 1 - x^2 [/spoiler] works Please ignore me.

>>	Anonymous Thu Aug 21 15:52:50 2014 No.6712153 >>6712149 no it does not http://www.wolframalpha.com/input/?i=1-%28%28x%29%5E2%29+%3D+x

>>	Anonymous Thu Aug 21 15:53:45 2014 No.6712154 >>6712153 There was supposed to be a negative in front of that 1; I made a typo.

>>	Anonymous Thu Aug 21 15:54:29 2014 No.6712157 >>6712149 I think you mean x^2 + 10 or something like that.

>>	Anonymous Thu Aug 21 15:54:44 2014 No.6712159 >>6712154 still, you were overthinking that: simle e^x suffices

>>	Anonymous Thu Aug 21 15:54:55 2014 No.6712161 >>6712149 also exp for instance

>>	Anonymous Thu Aug 21 16:18:49 2014 No.6712196 What's a good Game theory 101 book?

>>	Anonymous Thu Aug 21 16:32:31 2014 No.6712212 Can consciousness be explained as some kind of feedback loop?

>>	Anonymous Thu Aug 21 16:50:04 2014 No.6712236 Can the poster above me go back to /x/?

>>	Anonymous Thu Aug 21 17:22:02 2014 No.6712273 File: 180 KB, 2221x1216, kinetic_pot.png [View same] [iqdb] [saucenao] [google] how come the total energy of my spring pendulum isn't constant, although conservation of energy!? Epot := 0.5 * D * x^2

>>	Anonymous Thu Aug 21 17:42:06 2014 No.6712299 >>6695842 Is it possible for memories to be inherited?

>>	Anonymous Thu Aug 21 17:46:01 2014 No.6712308 >>6712299 Instinct?

Anonymous Thu Aug 21 21:05:34 2014 No.6712534

>>6711328
No. In "from X's perspective" it is assumed they have corrected for light travel time and other instrumental effects. The distance and speed were given from the star peoples' perspective, so the time for them is 20 years. The time for the traveler is a little less due to time dilation.

Anonymous Thu Aug 21 21:42:37 2014 No.6712576

I feel like I should know this, but I'm not sure, so it makes me feel stupid, regardless of whether or not the question is stupid.

Can an electron absorb a percentage of an incoming photon's energy to jump to another state and emit the excess as a less energetic photon? I know there might be an issue with the conservation of angular momentum, since a photon quanta must have a set angular momentum, but because of the combination of orbital and spin angular momentum of an electron in an atom, it seems there might be a way for the electron's change in L to be zero.

So are there any allowable transitions like this, or will the electron and incident photon not interact in such a way at all?

Anonymous Thu Aug 21 22:12:39 2014 No.6712615

>>6695842
When people say light is a wave, do they actually mean pulse? The whole wave description never sounded very sensible to me, and whenever i press someone knowledgable on it i get a description that sounds like a graph of energy that looks like a wave, ie a pulse. So why is it called a wave?

>>	Anonymous Thu Aug 21 22:15:37 2014 No.6712620 >>6712615 >So why is it called a wave? Because it is described by the wave equation, hence it's a wave.

>>	Anonymous Thu Aug 21 22:27:57 2014 No.6712641 >>6712615 >ie a pulse Look up 'wave packet'.

>>	Anonymous Thu Aug 21 22:36:58 2014 No.6712656 Why don't electrons stick to the nucleus?

>>	Anonymous Fri Aug 22 02:19:31 2014 No.6712899 >>6712576 It's possible. The cross section for that should be smaller, though, but don't ask me to calculate it.

Anonymous Fri Aug 22 02:57:27 2014 No.6712937

>>6696500
>>6696500
im a computer engineering student and I have to take a lot of EE Stuff. Electrical engineering is incredibly difficult. You need to understand relatively highly advanced math and apply it to advanced physics all in the fuckscape of a circuit with mostly unknown values. Glhf

Anonymous Fri Aug 22 04:54:51 2014 No.6713021

Excellent, I was looking for a thread like this.
Do any of you know of a paper published on a magazine with a title similar to "Journal of Trivial Matters" or "Journal of Trivial Research"; in which they discussed the impossibility of storing pokémons in pokéballs inthe form of electromagnetic radiation?
I downloaded it a few years ago, but lost it, and cannot find it now no matter how hard I google.
It may seem as if I'm joking, but I'm not.
Thank you.

>>	Anonymous Fri Aug 22 07:19:31 2014 No.6713128 >>6712937 >relatively highly advanced math Can you please be more specific?

Clareo Nex Fri Aug 22 13:11:06 2014 No.6713536

>>6712576
This is how both fluorescence and most glow-in-the-dark materials work, if I'm understanding your question correctly. The difference between the two is merely how long the unstable intermediate state lasts.

>>6712615
Coherent waves look like waves and it's hard to pick out what individual photons are doing.
If it's possible to pick out individual photons, then it means they're destructively interfering with themselves everywhere but a small volume.

>>	Clareo Nex Fri Aug 22 13:40:59 2014 No.6713566 How can we tell from a modern genome which genes have felt strong selective pressure?

>>	Anonymous Fri Aug 22 14:12:11 2014 No.6713594 >>6696341 If you represent species like classes: B inherits from D and E. A inherits from D and C inherits from E.

>>	Anonymous Fri Aug 22 14:15:30 2014 No.6713598 >>6713594 >If you represent this one thing as another totally different thing

>>	Anonymous Fri Aug 22 14:21:07 2014 No.6713614 >>6713598 He never defined "organism".

Necromancer Fri Aug 22 18:37:02 2014 No.6714085

Some random questions mostly pertaining to gravity:

Time is relative to space and gravity, causing spacetime to bend, makes time appear to move faster from the point of view of those on the more curved bits (Like on the surface of a planet). Is this right?

If so, when we say the universe is 14B years old, is this in terms of Earth's progression of time or from an all-encompassing point of view?

If you were to stand upon a ball of rock in space which wasn't moving and, say, you were in a car and you drove around this ball of rock. If that ball of rock gained mass over a period of time, thus creating a greater gravitational influence on spacetime, how would this appear from your point of view and how would this appear from someone observing you from a point where the gravitational influence of the ball of rock upon them was zero/negligible?

How does something moving through space observe time/affect time? It's own mass affects the curvature of spacetime so what sort of effect does this have? What about something which is massless? From the point of view of something with zero mass, what does travelling through space "look" like? What about when it enters the gravitational influence of other celestial bodies?

Does something of zero mass appear to move faster/slower through time when it enters something's gravitational field?

Is gravitational influence linear or exponential in terms of distance from the centre of gravity?

Assume I can move through matter. If I fell through the floor towards the centre of the earth, would the gravitational influence of the earth upon me decrease as I grew close to the centre? If the earth were a perfect sphere and then you were to draw a line from the centre of gravity to me and use this as the radius for another imaginary sphere (So a sphere which decreases in size as I move towards the origin with me acting as some point on it's surface), would I be affected only by the mass of the earth within this imaginary sphere?

Necromancer Fri Aug 22 18:40:14 2014 No.6714092

>>6714085

If you were not affected by any gravitational influences, including any that you might produce, would there be any progression of time?

From an external point of view, who would appear to move faster, someone on a planet or the person who is independent of any gravity?

>>	Necromancer Fri Aug 22 18:42:50 2014 No.6714098 >>6714092 >would there be any progression of time? I mean from your point of view.

>>	Anonymous Fri Aug 22 19:50:24 2014 No.6714184 How can I know if a given quadratic function is solveable or not for a given value?

Anonymous Fri Aug 22 19:53:19 2014 No.6714191

>>6714184
There is so much wrong with this.
Functions don't have solutions. By their nature, every element of a function's domain is a "solution" for said function.
Equations can have solutions.
>for a given value
The only way this makes sense is if you meant
>How can I know if a given value is a solution for a given quadratic equation?
In which case, the answer would be to plug the number in and see if the equation holds true.

>>	Anonymous Sat Aug 23 02:48:39 2014 No.6714723 >>6695842 How can i become one with the uniberse?

Anonymous Sat Aug 23 07:28:01 2014 No.6714922

So I'm studying geology at uni. At the moment we're having a mineralogy course and I can't wrap my head around double refraction. The difference between ordinary and extraordinary rays. Or what would be the "fast" and the "slow" ray.

We're having an example question in the style of

"Quartz has hexagonal 32 point group symmetry. Its unit cell dimensions are a = 4.914 Å and c = 5.405 Å. It is uniaxial and optically positive. The refractive indices of the slow and fast rays are 1.553 and 1.544, respectively.

What is the angle, θ, between the optic axis and [101] in quartz?"

After reading the lecture notes again and again, I don't get what I'm supposed to do here.

Note that I don't want anyone to solve it for me, I just need to understand the way to go about it.

Thanks in advance /sci/

Anonymous Sat Aug 23 15:49:57 2014 No.6715426

What is good book to learn multivariable/vector calc rigorously?
I've heard of marsden's vector calculus, apostol's calculus vol 2, spivak's calculus on manifolds, edwards' advanced calculus of several variables and munkres' analysis on manifolds...
But I have no idea which one to read, or if any of these at all.

>>	Anonymous Sat Aug 23 16:55:38 2014 No.6715538 Anyone know how hot a geochemical lab gets? I'm looking at a job posting for a lab helper and one of the things they mention is that the person will be working in a hot environment.

Anonymous Sat Aug 23 17:06:52 2014 No.6715565

>>6695842
Hello, /sci/!

There's something with integrals I wonder about. If you have computed a primitive function F of a given function f and you plug a random x into that function, what are you actually doing? I know about F(b) - F(a) but I'd like to know what F(b) and F(a) 'mean' separately. And also how that meaning is related to the random constant of the primitive

I can't find a clear answer, thanks in advance /sci/

Anonymous Sat Aug 23 23:12:02 2014 No.6716063
File: 4 KB, 470x180, root2xx2.png [View same] [iqdb] [saucenao] [google]

Hi, could anyone else with how to progress through pic related? I am trying to find the root of x^2 * 2^x - 1.

That's where I am at this point. Finding the range of x-values for which the series is convergent is the easy part, but in order to find the actual value, do I have to just plug and chug? This is not homework, just stuff I'm doing to review some calc.

Is there a way my summation can be simplified?

>>	Anonymous Sun Aug 24 06:32:41 2014 No.6716444 I'm keen on doing either Engineering or Computer science for a future career. Which one requires less retained information? Which one is more based on practicality and not as much theory?

Anonymous Sun Aug 24 14:50:52 2014 No.6717033

http://www.wolframalpha.com/input/?i=%28n-1%29%21*%28sum+%28i%5E2-i-1%29%2Fi%21+from+i%3D1+to+n-1%29
Hey /sci/, assuming I know all of HS math, can I derive that result from the input, or is there a "dirty little trick" like when summing geometric series?

>>	Anonymous Sun Aug 24 15:02:23 2014 No.6717052 >>6717033 Well, you have to know the Barnett's identity, but aside from that pretty straight forward.

>>	Anonymous Sun Aug 24 15:09:10 2014 No.6717062 >>6717052 I forgot that this is an epic meme, and googled it. Is it seriously easy though? Cause I've spent some time a month ago trying to solve it, but I couldn't.

Anonymous Sun Aug 24 15:22:24 2014 No.6717081
File: 136 KB, 696x378, Scientific_racism_irish.jpg [View same] [iqdb] [saucenao] [google]

I've been reading way too much /pol/ and Taki's Magazine and now I have a huge hang-up about racial science. Can I be directed somewhere that clears up this issue without appealing to political correctness and feels?

>>	Anonymous Sun Aug 24 15:43:35 2014 No.6717102 >>6717081 Sorry, no. It's too much of a touchy subject and you won't get any impartial sources before the 40s ever.

Anonymous Sun Aug 24 15:50:14 2014 No.6717110

>>6717081
That picture is 1950s science. It's no longer taken seriously since the onset of modern genetics. Race in general is considered a social construct in any scientific context. There's a lot of problems with trying to define science and statistical/genetic approaches typically use clustering algorithms with flawed methodologies. You won't find much addressing race in the context of modern science because it stopped being an issue years ago (2000-2004ish).

Here is a resource on heritability and race from 1996 though. It describes a bunch of basic logical fallacies that people like /pol/esmokers make on a regular basis in this context.
http://www.nyu.edu/gsas/dept/philo/faculty/block/papers/Heritability.html

>>	Anonymous Sun Aug 24 15:52:13 2014 No.6717111 >>6717110 >1950s 1899, actually. Thanks for the link, though.

>>	Anonymous Sun Aug 24 16:06:10 2014 No.6717137 >>6717110 >Race in general is considered a social construct in any scientific context. Sure.

>>	Anonymous Sun Aug 24 19:19:26 2014 No.6717359 If I have a lot of moles in my body am I at more risk of skin cancer?

>>	Anonymous Sun Aug 24 19:25:54 2014 No.6717368 If you traveled faster than the speed of light towards a star, and the star was dead by the time you got to it, would going backwards faster than light let you study it as if it were a still photograph?

Anonymous Sun Aug 24 20:06:32 2014 No.6717409

>>6717033
For <span class="math">i \geq 2,[/spoiler]
<div class="math">
\frac{i^2-i-1}{i!}
= \frac{i(i-1)}{i!} - \frac{1}{i!}
= \frac{1}{(i-2)!} - \frac{1}{i!}.
</div>
So for <span class="math">n \geq 2,[/spoiler]
<div class="math">
\sum_{i=1}^{n-1} \frac{i^2-i-1}{i!}
= \frac{1^2-1-1}{1!}
+ \frac{1}{0!} + \frac{1}{1!}
- \frac{1}{(n-2)!} - \frac{1}{(n-1)!}
= 1 - \frac{1}{(n-2)!} - \frac{1}{(n-1)!}
</div> and <div class="math">
(n-1)! \sum_{i=1}^{n-1} \frac{i^2-i-1}{i!}
= (n-1)! - (n-1) - 1
= (n-1)! - n.
</div>

>>	Anonymous Sun Aug 24 21:04:05 2014 No.6717476 >>6712129 Quantum Computer Science. >be specific Designing algorithms for quantum computers.

>>	Anonymous Sun Aug 24 21:15:09 2014 No.6717484 >>6695842 What if I was alive for 7 billion years and my memory got wiped out before I was born?

>>	Anonymous Sun Aug 24 22:18:56 2014 No.6717591 Does anyone have that (or a) /sci/ gag where the guy used Pythagoras' Theorem in a proof by combining it with another equation that also used the variables a, b, and c? I totally forget what it was.

>>	Anonymous Sun Aug 24 22:54:51 2014 No.6717628 Is here an ok place to test JSMath? I'd hate to try and seriously answer a post and fuck up the formatting. Here goes. <span class="math">2+2[/spoiler]

>>	Anonymous Sun Aug 24 22:56:02 2014 No.6717629 >>6717628 OK, going to try a slightly harder one now. <span class="math">2^{2}[/spoiler]

>>	Anonymous Sun Aug 24 22:58:09 2014 No.6717632 >>6717629 next, from the /sci/guide: <span class="math">4+3*2/10=10[/spoiler]

>>	Anonymous Sun Aug 24 23:00:46 2014 No.6717635 >>6717632 so according to http://detexify.kirelabs.org/symbols.html I can also post a bunch of stupid symbols, just going to try that now... <span class="math">\aquarius \astrosun[/spoiler]

>>	Anonymous Sun Aug 24 23:01:54 2014 No.6717639 >>6717635 ...ok, didn't need those symbols anyway...

>>	Anonymous Mon Aug 25 00:40:39 2014 No.6717735 >>6695842 >the relationship between matter and energy >the relationship >the There are MANY relationships between matter and energy, Pleb. Do you even Physics?

>>	Anonymous Mon Aug 25 17:23:58 2014 No.6718677 >>6695842 What If me and my descent exercise our legs and never our upper body for 50 generations. Will our descendants look like?

>>	Anonymous Mon Aug 25 19:46:33 2014 No.6718839 >>6717409 Oh man so It was that easy? Thanks a lot for your help.

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/sci/ - Science & Math