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/sci/ - Science & Math

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2909169 No.2909169 [Reply] [Original]

Post some questions, answer some if you know what you're talking about.

>> No.2909182

Is there such thing as a "stupid question"?

>> No.2909181

I understand evolution is mutation followed by natural selection, but how are each genes caused to mutate and how can natural selection work when only one gene might get mutated within a phenotype?

>> No.2909190

>>2909181
Genes are mutated by thinks like radiation and copying errors, and they can influence the selection of the phenotype in the same way if you put a strong rower in a rowing crew the boat will travel a bit faster. I'm not too sure on the later answer though.

>> No.2909192

how can u beleive in evolution if its just a theory (a geuss)?

>> No.2909189

>>2909182

Yes, questions like "why should I use logic?"

>> No.2909195

>>2909182

According to my physics teacher, there is no such thing as a stupid question, just wrong questions.

>> No.2909199

Why is gravity?

>> No.2909203

>>2909181
Some genes kind of piggy back on other genes. If you get Gene A, you'll get Gene C, too. So the whole "only one gene gets mutated" idea there is kind of flawed. Yes, only one gene gets mutated sometimes, but >usually< there's another.

And christ, why the evolution question to start with.

>> No.2909204

>>2909197

You must be new here.

>> No.2909205

>>2909197
That's right. Feed the obvious trolls.

>> No.2909207

>>2909199
Gravity is the force of mass being attracted to other mass. The greater the mass the greater the force.

>> No.2909212

>>2909199

Gravity doesn't exist. Massive objects warp the space around them, and the "pull" of gravity you feel is simply you falling into the curve which happens to be directed to the center of the earth.

>> No.2909216
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2909216

>>2909192

>> No.2909221
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2909221

I know it's a troll image, but why wouldn't it work if the pipe was sealed at the bottom and was layed from the sky, so that it would originally be from the vacuum.

>> No.2909222

>>2909212
Let's not confused the children and stick to what they know from textbooks.
(There's also another theory I've seen about electromagnetic forces being what makes things orbit in space, while gravity is what works while on the surface of a massive body).

>> No.2909223
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2909223

How many photons of visible light are in a 1ft cube of sunlight on earths surface?

>> No.2909229

>>2909221

The same reason our atmosphere isn't sucked into space. Gravity would hold the air down.

>> No.2909230

>>2909189
actually its a very good question pertaining to the scientific process. There are no stupid questions. science is about asking question about how things work. There are misplaced questions , such as asking philosophical questions to a scientist. Science answers 'how'. Philosophy answers 'why or at least atempts too.

>> No.2909231

>>2909212
source or gtfo

>> No.2909233

If you took a meter cubed of plasma from the core of the sun and put it in the centre (centre of mass) of the Atlantic ocean, what would happen?

>> No.2909236

+1 internets for the first anon to attempt to answer this

If evoked neural dynamics can be explained by phase resetting of ongoing oscillatory activity, how can we distinguish between a single sub-cortical (eg thalamic) current generator, and multiple cortical sources?

>> No.2909242

>>2909231

Give me a source that says objects with mass are "attracted" to each other.

>Protip: They're not.

>> No.2909241

>>2909231
He chose his words pretty awfully, but the general thought was right, according to GR.
However, many phenomena involving gravity can be explained with the much simpler Newtonian model. (The Einstein equations are one ugly fuck.)

>> No.2909238

Why do some people thinks blacks aren't stupid and violent? When exam results , iq tests, crime statistics and genetic make up prove otherwise

>> No.2909240

>>2909222
>implying what is taught is most text books isn't equally as a valid of a theory considering we have no way of testing either

>> No.2909249

>>2909241

Yes, but to say that gravity doesn't exist is erroneous. Gravity is the curving of space time around mass, or what causes space time to curve. To say that there is not gravity, only curvature is rather silly.

>> No.2909256

For convex surfaces of fixed intrinsic diameter, is the doubled disk the one with the greatest area?

>> No.2909258

>>2909242
You, sir, don't know how science works. Just because you can use quantum field theory to find out whether you've switched the lights on ten minutes earlier doesn't mean the simpler models (such as looking) are wrong.
Similarly, if Newtonian gravity makes accurate enough predictions, there's no need for curved space.

>> No.2909262

>>2909221
gravity. in fact if you put it in it would just drop to the floor, because of the no air resistance. even if you left the door open so the inrushing air would drag it out, gravity would still pull it down and eventually the air would just equalise with the atmosphere. none of the air would go into space

>> No.2909265

What in fuck's name is gravity? Also, how the fuck do black holes do what they do?

>> No.2909270

>>2909212
we aren't living on a single plane so your idea is invalid

>> No.2909272

>>2909249
Agreed. The "gravity doesn't exist" is precisely error as saying "centrifugal forces don't exist".
Gravity exists because we can observe objects being pulled together. It's now up to the model to explain why they do so (Newton: magic, Einstein: curvature).

>> No.2909273

>>2909236
>evoked neural dynamics can be explained by phase resetting of ongoing oscillatory activity
I see you've read Klimesch et al, 2007. I think you already know the answer, but just in case you don't: there are two things we can do to eliminate sub-cortical sources.

Current source density is a technique which gets rid of shared activity between electrodes due to volume conduction. You subtract the weighed (according to distance) common activity from each surface electrode (be it EEG or MEG) from each other electrode.

Alternatively you can apply the Laplace transform. It's less effective, but computationally less intensive.

>> No.2909284
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2909284

>>2909273
lolwat, I've posted this question I copy pasted from another thread a while back at least 5 times. This is the first time anyone answered it.

mad props

>> No.2909290

>>2909272

Centrifugal force doesn't exist. They called it a "force" to explain it to people like you that don't want to understand.

>> No.2909302

Not a question but I was wonder what other peoples opinions are, if, natural selection and evolution are all laws the universe, then would it not be right to assume that at least in one point of an intelligent creatures evolution, the would take a humanoid shape? Assuming they are carbon bases, have a similar sized and shaped planet and breath oxygen.

>> No.2909303

>>2909290

Centrifugal force is a reaction force, it doesn't exist without some other force. It exists as much as you want to define existence. The Normal force is just like this, contingent upon the perpendicular component. If you say that the normal force exists, then centrifugal forces exist.

>> No.2909317
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2909317

>> No.2909318

Question:

Can ion propulsion be effectively implemented here on earth?

>> No.2909324

>>2909302

No. Our having four limbs and the way they're arranged is caused by evolution constantly reworking the body of a fish. The humanoid shape is not the best at anything, it's just a tortured kitbash of a fish. Look up how the nerves that control your voicebox are arranged. We're just twisted, mutated fish. Any other species on an alien world would also be the twisted mutated version of their most successful sea life, so them having a humanoid form as well would be an incredibly unlikely coincidence.

>> No.2909344
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2909344

>>2909290
Good thing I've written a copypasta answer for uneducated loudmouths like you down a year ago. (Warning, it uses superhardcore math, such as fancy double bars for vector lengths)

>> No.2909350

>>2909192
It is amazing how often this comes up. It shows the confusion that the public has as to the meaning of "theory".
Science is a subject where one must realize that they might be wrong, at all times. In publications, you will almost never see the word "this proves our theory". There is only correlation. What a scientist would say is that "observations support ___". Even if experiments align perfectly with an idea, they can never tell it a theory is absolutely right. For example, until 1905, in experiments, every piece of data scientists had pointed to the standard laws of Newtonian mechanics working. And yet they turned out to be different at high velocities! Thus, no scientist in their right mind would ever say that a theory is a fact.
A guess, or something that has not been checked against current data/experiments is called a hypothesis. So if I were to say "There are not a lot of scientists on /sci/", then it would be a hypothesis, until there was any data backing it up.
A theory on the other hand, is as close to "fact" as science can get. A theory is something supported by current evidence, such that there is no reason to think it is incorrect. Those are things like gravitation, quantum mechanics, electromagnetism, and yes, evolution. (would you say that your computer operates on a guess? After all, it operates using the predictions of "theories"!)
So to finally answer the question, evolution is no longer a guess, it is a theory - evidence fits the predicitons that the theory of evolution makes, and thus there is no reason to suspect that it is incorrect.

A theory is therefore a tribute to the idea in science that there is rarely absolute knowledge about the universe, we can only try not to fool ourselves. Leaving our ideas as theories instead of facts allows us to question if the current understanding is the best for explaining what we see around us.

>> No.2909353

>>2909324
I wasn't saying it was perfect, but it is the best at something - long distance running.

>> No.2909359

>>2909350
>>2909344

Do you tripfags know you're being trolled and just answer anyway, or are you that fucking stupid?

>> No.2909367

>>2909350

Theory ≠ Fact

∴

Evolution ≠ Fact

Thanks! This is what i've always thought but you cleared it up for me!

>> No.2909366

>>2909359 or are you that fucking stupid
I'm not, got that in written form from multiple known scientific instances or personalities.
Any further questions? (I'm eating pizza. There's no way you can troll me in this state.)

>> No.2909364

>>2909344

Ah, the derivation of rotational acceleration. It's quite elegant, is it not?

>> No.2909376

>>2909364
It's one of the ugliest things I've ever done in my spare time ;)
Seriously, I couldn't find a book doing the entire calculation. They all stopped at some point and said "can be shown" or "skipped some steps" and presented the omega \times result. Or they used weird trigonometry pictures to derive it.

>> No.2909387 [DELETED] 

>>2909367
Well, seeing that many *congressmen* seem to actually believe that, then I think it deserves an honest explanation, despite a troll attempt.

>> No.2909390

>>2909367
....
A Theory explains facts but isn't a fact itself.
Therefore, Evolution isn't a fact but it explains facts.
But I guess you can take whatever slant you want on his post.

>> No.2909397

>>2909376

Actually looking back at my notes, I have to agree with you.

>> No.2909400

>>2909359
Well, seeing that many *congressmen* seem to actually believe that, then I think it deserves an honest explanation, despite everything.

>> No.2909418
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2909418

Question:

Can ion propulsion be effectively implemented here on earth?

>> No.2909422

>>2909390
>>2909350
Please don't feed the troll.

>> No.2909431

>>2909390

I can explain facts, does that make me a theory?

You just loose a little faith in your science?

>> No.2909447

>>2909418
on earth? Like a plane flying around with it? No.

>> No.2909454

How are physical constants like G and K determined? My professor just said that they're numbers that "make the formulas work" but how are they determined in the first place?

>> No.2909462

>>2909454

If you mean how do we find them, then yea, we look for whatever constant makes the formula works. We look for the constants of proportionality.

As to how they come about in the first place, we have no idea.

>> No.2909488

>>2909418
Ion Propulsion only really works in a low-friction environment.
You could chain a stupid amount of engines together to create the same thrust as a combustible engine, yet it will neither be faster no more energy efficient than the latter

>> No.2909516

Not really a question, but i'm looking for some site for data of nuclear reactions
I'm looking for the cross section of the Be9(n,2n) reaction for like 3 hours and couldn't find anything

>> No.2909519

How come 1 + 2 + 3 + 4 + ... = -1/12 ?

>> No.2909526
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2909526

Fucking density, man.
I want to be able to form a ball made out of a correct ratio of concrete and styrofoam to make it float in the middle of a pool or something.
But science tells me that I can eat a bag of dicks.
Why?

>> No.2909531

What is actually the significance of Planck time and Planck length? Is it like the resolution, or am I way off?

>> No.2909538

>>2909526

What? as long as the density of the boat is less than the density of the water, it will float. I heard about a group of seniors who made a boat out of concrete once.

>> No.2909539
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2909539

What is preasure?
What is temperature?
What is more complicated?

>> No.2909545

>>2909538

No, floating and sinking are easy modo.
I'm talking about making something float... underneath the water!
Not submarines. I mean some non-mechanical object that'll just sit there.

>> No.2909553
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2909553

couldn't "creation," the natural realm, whatever you want to call it, be a work of art, the product of a creative mind?

>> No.2909559

>>2909545

Well, neutral buoyancy, which is what you are going for, could be obtained by being careful with the measurments. But if Styrofoam absorbs water in any way, that'll fuck you over.

But I can't think of any reason why this wouldn't work.

>> No.2909563

>>2909545
That is actually possible if there are other liquids than water.
I remember reading a book and doing an experiment as a kid where I poured water, syrup and something else I forgot in a bottle and then dropped three objects in it. The objects floated on 3 different levels.

>> No.2909567

>>2909559

My Physics 101 professor was pretty adamant that it wouldn't work. Even stuck it on a midterm.

>> No.2909566

nature vs nurture
sociologists vs anthropologists

which is correct and which field is better?

>> No.2909574

>>2909563
http://www.hometrainingtools.com/liquid-density-project/a/1305/

Here. Try it.

>> No.2909577

What are the observed phenomena that can't be explained using Quantum Theory but can with M-Theory??

>> No.2909587

>>2909553
>>2909553

This is heading into the philosophy of art. To me, art requires conscious manipulation. Beaches are beautiful, but because no one made it, it's not art.

>> No.2909590

>>2909531
The scale at which quantum gravity may become important.

>> No.2909594

>>2909563

Hmmm. So you could realistically fill a fish tank with water, some fish, a bunch of clear oil, and drop some stryrofoam props like a stopwatch and a M.C. Escher bust to make the hipsterest fish tank in the world?
So long as goldfish are smart enough not to swim into the oil, I think I'm onto something here.

>> No.2909595

I don't understand how centrifuges work. Can someone explain it in layman terms. What makes the more dense stuff go to the bottom of the tubes when the tubes spin in circles really fast?

>> No.2909603

>>2909567
It's basically the same thing as sending a hot air balloon as far as it goes. Where do you think it stops? Where it's in balance with the surroundings.

The same things happens if you balance your objects density in water just right. You have to be very precise though. Math it.

>> No.2909605

>>2909577
Gravity.

>> No.2909609
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2909609

>>2909594

BEHOLD! They use it as a fryer and not kill the fish. Somehow.

>> No.2909613
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2909613

>>2909577
the only thing M-theory explains in real life is the fact that Witten is a powerhorse in academia

>> No.2909621

>>2909609

FUCK!
Why are my best inventions already done?

>> No.2909648

>>2909454
G is measured by taking two objects with known mass, placing them at a known distance, and measuring the gravitational force between them with a very sensitive device such as a torsion balance.

>> No.2909683

>>2909567

In a fluid of uniform density, yes it is impossible. The pressure difference will always cause the material to float or sink...not just hang in the middle somewhere. It's not the same as in the air as air's density changes with altitude.

>> No.2909715

>>2909539
To put it simply:
Temperature is the average energy at which molecules are banging around.
Pressure is the force they make on the walls of the container, per unit area.

>> No.2909761

>>2909715
I'm not a fan of "temperature = average kinetic energy", it seems derived.
>To put it simply
put it as accurate as possible.

>> No.2909851

>>2909761
Temperature is defined as
<div class="math">T = \frac{\partial E}{partial S}</div>
where E is the energy of the system and S is its entropy. Pressure is defined as
<div class="math">p = -\frac{\partial E}{\partial V}</div>
where V is the volume. I can ofcourse also define them from a partition function, i.e. in a statistical mechanics way.

>> No.2909858

>>2909851
should ofcourse be
<div class="math">T = \frac{\partial E}{\partial S}</div>

>> No.2909940

>>2909851
okay, but does this explain anything?
like I still don't get it.
This way it's only some parameter.
Would you say... can one feel it more intuitively?

>> No.2910343

>>2909613

Didn't get the joke :(