/sci/ - Science & Math

>>6915968

Questions in regards to physics?

Just a wild guess based on your name, but still need verification.

how does it feel to be a failed mathematician?

>>6915968
>"Physics Guy"
>Picture of a based mathematician
You're pathetic.

Why is it that not having found the higgs at lower mass (than 125 GeV) suggests supersymmetry might be ruled out. Conversely, why exactly do more obscure theories predict much higher masses?

I had a lecture on supersymmetry and some on Standard model QED phenomenology, so you can use that language.

>>6915982
>being this new
Physics Guy is a CERN physicist, haven't seen him post on here for a while.

>>6915968
how does displacement current tie into relativity?

>>6915968
When you are doing tensor calc or tensor calc related things, ie GR.
How do we derive the covariant or contravariant basis from essentially nothing.
My lecturer stated something about defining some arbitrary invariant position vector.
Then we define our coordinate system and then we redefine our position vector as a function of our coordinates.
Finally, we take the partial derivatives of our position vector with respect to our coordinates and we somehow recover the covariant basis.
My question: what the fuck?
Could someone show me an example of this actually being done or tell me how I could do it for a simple coordinate system like cartesian or polar coordinates?

>>6915968

Is Time a construct derived from experience or is it an a priori category?

>or is it an a priori category?
>>6916036
It's a category and the world is a topos.

How come creationism and climate change denial are popular in America? THey don't exist much in the rest of the developed world.

Is the so-called EM Drive bogus? If so, why?
http://en.wikipedia.org/wiki/EmDrive

>>6916149

Not him, but it's multiple confounding factors.

Once a subject isn't taught enough AND it is politicised, the common man will reject it. American education struggles with science, so people fallback to their political prejudices. America is a conservative country, so we get creationism and anti-eco shit.

Liberal pockets of America with poor education face this as well (the debates around GMOs and fluoridation in Oregon, for instance), but they don't have enough influence to affect America nationally.

>>6916173
I'm gonna build one for my senior project and find out.

Can you tell me the most exciting thing being talked about in CERN right now? (And it better not be whats on the lunch menu :)

How long do you think it'll be before we'll see quantum supercomputers being used by Fortune 500 companies?

Why are cats so soft

>>6915968
Does there exist a non-trivial Euclidean field theory for any simple gauge group G?
You do this part and I'll do the mass gap part.

>>6916948
Because there is a god.

>>6915968
Is this question fucking retarded?

>>6915968
Ryuko Matoi moves around Nui Harime in a radius of 0.25 body lengths at 0.5 times the human flicker frequency. If this happened in the real world would she be severely injured, dead, or pulp? Justify your answer.

I am not a TA trying to write test questions for a stupid undergrad class btw.

>>6915968

Why the fuck does the Physics guy have the pic of based set theorist Cantor? Must be one of those physicists who wanted to become a pure mathematician but wasn't good enough to become one.

Did you ever get burnt out in undergrad? I sometimes feel like I don't even know anything, having so many courses, it's hard to truly learn something in depth. How did you pull through in those shitty days, what kept u going?

>>6917044
>burnt out in undergrad
what Uni you go to m9? major? current amount of units being taken

>>6917038
>based set theorist
>based
That is the shittest adjective, it is used so often it basically means "good". Learn some new words.

>>6916948
they are so soft

Will you go to this website and tell me what you think?

http://www.breakingtruth.info/

>>6917102
but why are they so soft?

>>6916001
Sorry for the delayed reply. I took a nap.

>Why is it that not having found the higgs at lower mass (than 125 GeV) suggests supersymmetry might be ruled out.

Supersymmetry is merely a class of mathematical theories that relates fundamental particles to a supposed “superparticles”. There are dozes of such theories, all with additional requirements and concepts. However, since the scientific method incorporates occam’s razor, the most heavily studied models are those that incorporate as least new shit as possible. In such models, the strength of the weak nuclear force sets the Z particle mass and the Higgs particle mass. The model even implies that the Higgs mass (126GeV) can’t be above the Z mass (91GeV). The fact that we actually “found” the Higgs mass above the Z mass, eliminates these “simplified” super-symmetry models from being true.

>Conversely, why exactly do more obscure theories predict much higher masses?

aka …..“How could we get the Higgs mass way above the Z mass? “

1) We use the simplified symmetrical-models and modify them, by saying the large quantum corrections (mostly top and quark effects) move the inherit Higgs mass (set by the Weak force ) up.

2) We use way way more complicated super-symmetric models

We are currently looking for signatures of both possibilities. And from a scientific stand point (occam’s razor) we would favor the possibility of 1) (aka focus more on that). Only time will tell though. I actually work on super-symmetry. My phd was looking for a very specific super-symmetric signature in category (1). I didn’t find it. No straw off my back though. Like the overwhelming majority of scientists, I have no dogmatic investment in any scientific theory or work. It’s all about what we can prove (back up with evidence and reason), not our fucking feels.

>>6916013

>how does displacement current tie into relativity?

I’ll assume you mean “special relativity”? Classical electromagnetism was codified by Maxwell in the form of Maxwell’s equations. These describe all electromagnetic phenomena. When compiling the equations, Maxwell noticed what looked like an inherit symmetry between magnetism and electricity, save for one missing “electric” term. In a stroke of genius, Maxwell decided to add this term, “displacement current”, aka rate of change of electric displacement field, even though there wasn’t really any physical evidence for it at the time. This caused some controversy (we eventually did find physical evidence for it, aka electromagnetic waves).

At some point Einstein came along and formulated special relativity. For something to be compatible with special reality it needs to be lorentz invariant. Remarkably, Classical electromagnetism was already lorentz invariant! It was automatically compatible with special relativity, because of Maxwell’s extra term! Einstein even published exactly how this all works, and how the symmetries works. It turns of that the “displacement current” and the “magnetic intensity” are basically symmetric to each other, in term so special relativity.

>>6916036
>Is Time a construct derived from experience or is it an a priori category?

Time is the label we give to a class of observed phenomena. No need to make things so complicated kid.

>>6916149
>How come creationism and climate change denial are popular in America?

Religion. The USA has a high religiosity compared to other civilized places. In fact, it is the outlier! Religiosity goes hand in hand with dogma. And it just so happens to a lot of the dogma promoted by the religions in the USA encourages people to go against or doubt science.

>>6916895
>Can you tell me the most exciting thing being talked about in CERN right now?

Turning the LHC back on and getting new data. Getting the first ever data from 13TeV collisions (previous it was 8TeV).

Here is one that bugs me:

Let's say there is an object and some force f1 pulling it to a surface with FRICTION (like a massive rock and gravity).

Let's now say a force f2 acts on that object perpendicular to f1 (like a human pushing that rock). That force f2 does not manage to move the object visibly for a human eye.

Question:

1. Does it mean only because it doesn't move visibly, that it doesn't move at all? (I know this sounds silly)
2. If force f2 doesn't move the object, would it move the object given an infinite amount of time?

Or in other words: Is there a certain threshold which you need to pass to get things REALLY moving, OR, is this transition smooth and you get as much movement as much force you put it, regardless of the temporal distribution of the force.

>>6917201
Not op, but...

Kinetic and static friction?

There's a certain threshold force you need to apply to an object to overcome the friction force to get it to move at all. Friction basically pushes back against you until you get to that threshold force.

After you've surpassed the threshold force however, the force of friction pushing against you actually drops a bit, and becomes constant (assuming that the normal force remains constant).

This is only coming from a PHYS 1 background on mechanics though. I could be missing something here.

>>6917208
http://hyperphysics.phy-astr.gsu.edu/hbase/frict2.html

>>6916173
>Is the so-called EM Drive bogus? If so, why?

Yes, probably Bogus. Why?... Because the methodology used to introduce the claim is similar to a "used car sales-man" trying to sell a lemon. If someone tells me they have a dragon under their bed (or EM Drive), I want proof and peer-review. I ain't just going to take their fucking word for it.

It is all about burden of proof.

>>6916906
>quantum supercomputers being used by Fortune 500 companies?

10-15 years? Maybe one company already uses them. Fuck if I know or really care.

>>6917044
>Did you ever get burnt out in undergrad?

No

>How did you pull through in shitty days?

Hobbies, Sex, Drinking, Friends, Family, Weed, etc.

Physicists are humans; socials creature. There are known and common way to cheer humans up. This isn't rocket science.

>>6917208
Okay, thank you for the answer.

One more thing I don't understand: Let f_t be the threshold force you need to get the obect moving. Let's say f1 << f_t is applied to the object, where does the force go? Heat?

If so, what if you put f1 in an infinite amount of time - i.e. you put in an infinite amount of force into the system, does the rock still stand still? If so, where does all the infinite heat go?

>>6917038
>Why the fuck does the Physics guy have the pic of based set theorist Cantor?

Because I admire Cantor and enjoy his body of work. Being a physicist doesn't mean that you can only like "physicists" or "physics".

News false: Physicists are people. And as people they have hobbies and interests not necessarily related to career or profession.

>>6917182
>Time is the label we give to a class of observed phenomena. No need to make things so complicated kid.

Related question:What do you think of Barbour's idea that time is an illusion? Are you willing to stick your neck out and predict whether unified physics (if we reach them in our lifetime) will or will not have a term in them for time?

>>6917236
>One more thing I don't understand: Let f_t be the threshold force you need to get the obect moving. Let's say f1 << f_t is applied to the object, where does the force go? Heat?

>Where does the force go? Heat?

Heat is energy, not force, so it definitely doesn't transform into heat.

But the real answer to your question is: You are confused (You knew this already). Force doesn't "go" somewhere. It's not a quantity being spent.

Imagine, if you will, that you lean a fencepost against our boulder. Much less force than what it takes to move the boulder.

Then you leave. You come back in ten years.

Fence post is still there, boulder hasn't moved. Force applied is still exactly the same as before.

>>6916906
Too many factors to give a reasonable answer, It could happen within a year with the right designing or producing them. I'm fairly sure if a computer came along that was >100x more powerful than what we have today ( keep in mind quantum computers can run classical computations natively) It would be adopted by business then given time consumers.

what's your thought on aliens or other life forms being able to see us from another dimension? if we can only see in the second dimension, other life (such as aliens) could be in the 4th or 5th dimension and are able to see us in the 3rd or 4th dimension, do you think this could happen?

>>6917257
No. Interstellar isn't a very good movie. Can we see into the second dimension? Other spatial dimensions aren't something existing along side eachother, they are ideas created by humans.

>>6917260
this isn't related to interstellar, as we live in the 3rd dimension we can only see the second dimension, im asking you if you think that other life can see us in the third dimension, and live in the fourth dimension

I want a function that compies this one but x does not equal y. The slope resembled the function f(x)=e/x, but the two actually deviate a little. Can someone help me out?

>>6917247
>What do you think of Barbour's idea that time is an illusion?

I (and probably the majority) of physicists are not familiar with him. From a quick Google:

>"Barbour: Time-less physics time as we perceive it, does not exist as anything other than an illusion"

This could be true. However, it is kind of trivial sematics. It is a meaningless philosophical circle-jerk. For instance, we know "color" (example red), is an "illusion" (in his sense). Yet, we don't go around acting like faggots saying it is an "illusion". Color merely being a completely understood byproduct of our senses, that doesn't corresponding to any fundamental property of the universe, doesn't mean we should call color an "illusion", does it? Instead what we do is say color isn't "fundamental". But, yeah, we could call it an illusion. It is sematics.

>Barbour cont: "a number of problems in physical theory arise from assuming that it does exist"

[citation needed]

In GR we do indeed disregard "time". It is useful to do for certain calculations. So, I am not exactly sure what problem Barbour has, but indeed we can and do disregard time if need. Maybe, there are other "systems" that could be better modeled without time (like GR). Barbour kind of needs to prove it though, instead of just assuming it.

Does the uncertainty principal stem from the fact that quantum mechanics don't account for friction? I mean the electron is moving through the air and at that scale friction should have a non-negligible effect.

>>6917266
>>6917257
>what's your thought on aliens or other life forms being able to see us from another dimension?

I think it might be cool if certain types of "dimensional aliens" exists, but that is all I can say. I like sci-fi.

>Do you think this could happen?

I don't know. I don't even know if it is "possible" or "impossible". Because possibilities are still claims concerning truths, right? Not everything is "possible". Possibilities are limited. To claim something is "possible", you actually have to prove it is possible.

I know this might is confusing. Here is a clip explaining how possibilities work, if that helps.

https://www.youtube.com/watch?v=LqNDrOxhZho

>>6917255
*right people

>>6915968

will a photon's wavelength change when it travels in a dilated area of spacetime? like near a black hole, or through the universe that is expanding.

if so will it lose/gain energy? if so doesnt that violate conservation of energy?

>>6915968

Thoughts on pilot-wave theory, brah? How bout' your collegues? Describe daily routine in your job.

>>6915968

Im a geoscientist but im kind of sick of stuggling to understand something so a rich guy can pay me shit and be more wealthy than he already is, my question is should I persue meteorology, astronomy or just quit STEM and have a fun, nice job.

>>6917510
>will a photon's wavelength change near a black hole?

Yes, gravitational dilation does changes the frequency of light. Its called gravitational redshift.

>does this redshift make it will it lose/gain energy

Yes

>does this violate the conversation of energy?

No. If I drop a ball from the top of building, does it violate conservation of energy when it falls? No... It gets potential energy from the gravitational field, and turns it into kinetic energy. Same with the photon moving through gravitational changes.

>will a photon's wavelength change from the universe expanding

Yes. They lose energy.

>doesn't this violate the conversation of energy

No. There is no conversation of energy (the way you are used to it) when space stretches in that manner. Conservation of energy is not a "first principle". It is derived and only applies to certain kinda of spaces.

>>6917510
no. if space time is dilated, then the change is not measurable to anybody in that space time, which you have to be to observe the photon. this is because the observer is equally dilated.

>>6915968
I've asked before on /sci a relatively simple question: Are there excactely equal amount of electrons as protons in the universe?

Answers were that so far no observations suggested there is net charged electrical objects/galaxies in the univers so it appears that the answer is yes. Then I wonder: Why and how? Could not the one exsist without the other?

What do you get when you cross an owl and a bungee cord?

If we consider the entire universe as an entire closed sistem, it's angular momentum has been zero from the beggining?

>>6917549
>Thoughts on pilot-wave theory, brah?

If I recall, it was a last ditch attempt of some physicists to dogmatically cling to determinism. It is highly looked down upon as nonsense. Faggots constructing super convoluted models to cling on to preconceived notions is just straight bullshit, straight bullshit.

>How bout' your colleagues

No one gives flying fuck about it. I doubt any of them even know about such an obscure shitty thing. It isn't taught or considered mainstream physics. The only reason I know about it was from the faggy philosophy course.

Is there any cool physical insight in electromagnetism when formulated as the effect of curvature of a circle bundle or is it just a neat mathematical trick?
I'm kind of aware that it is somehow the starting point for gauge theories but I was wondering if classically one could maybe gain any insight on the theory.

>>6915968
195 Here. thank you for your reply

Well looks like you're only answering the retarded questions here.

>>6917252
>Imagine, if you will, that you lean a fencepost against our boulder.

That's not what I meant. Maybe I used the word force wrong. What is meant is this:

What if a person was pushing the rock with the strenght of his muscles. Then resting, then pushing again, and so to infinity.

Would the person move the boulder eventually? Does it move it a little bit with each push? And if not, where does this "pushing energy" go?

>>6915982 OP
Thank you for the replies. I have developed an understanding that time is function of the universe and not a dimension etc, now you postulate this:

> There is no conversation of energy (the way you are used to it) when space stretches in that manner. Conservation of energy is not a "first principle". It is derived and only applies to certain kinda of spaces.

Its going to take me some time to get my head around that statement, can you explain it to a layman? please?

Why take physics at uni?
I've applied for it, but a lot of people are telling me that it will be hell and not fun at all.
Why did you decide to do so?

>>6917632
>Are there exactly equal amount of electrons as protons in the universe?

No one knows. My guess would be no. I don't think it really fucking matters though. It really isn't an important question.

>How could electron exists without protons?

Why do you assume they are "opposites" and have to exist together? Why?

A proton is a heavy massive particle, composed of other more fundamental particles. An electron is a very light particle with no internal structure. They aren't "opposites", just because they have opposite charge. Muons and taus also have -1 charge as well! So do a lot of other particles!

If you want to ask "does the universe have a net 0 charge?" That is a somewhat meaningful question. But, just picking two random particles in the universe and assuming they must exist in equal parts because they have the opposite charge thing, seems kinda silly.

Unless you have some other motivation for this "opposite" thing you seem to imply?

>>6917685
Its 'derived' I dont understand, time is a derived function of energy, matter and movement. If The laws of conservation of energy can fluctuate, then time can too. Or am I wrong?

>>6917681
mind answering this Physics Guy?

>>6917689
My motivation just stems from the basic observation that I've been taught in school that most of the matter in the universe consists of atoms with the same number of electrons and protons. The exepetions, ions, plasma, alpha- and beta particles, are unstable and short lived. I jusst think its a strange coincidence that there should be an equal number of these two particles. My guess was that it could be explained in terms of particles interacting over time and converted to each other in such a way that they exist in equal numbers.

I will admit that Im speculating with plebeian ideas that like ying and yang, one cannot exist withouth the other, because each is caracterized as the absence of the other, but its also possible to view it as one whole.. By the same line of thought: Positive and negative charge is one entity but viewed as two separate entities most of the time. This is why we have the same number of electrons and protons (or other charged particles add to 0).

According to Newton's second law every force has an equal force opposing it. But then how is movement possible? If all forces are always balanced, surely nothing can move?

some chemistry for u that i wasnt able to solve for the past 30 minutes

>>6917685
>time not a dimension

Time is a dimension. We define "height, depth, width, and time" as dimensions, because they obey certain relationships to one another. And "dimensions" obey a certain relationship to "not dimensions". Simple as that.

>time is a function of the universe

That is a useless nonsensically philosophical circle jerk kind of a statement. It is meaningless. It could equally say "beer" is a function of the universe. It would be just as valid, meaningful, and insightful as your statement.

>Now you postulate this

I am just stating a fact. I didn't actually postulate that shit. This is known physics that was done ~100 years ago. We know that all of the supposed "conservation laws" are just the consequences of a certain types of inherit symmetries in a system.

Symmetry<->Conservation Laws

http://en.wikipedia.org/wiki/Noether%27s_theorem

>>6917726
First, you mean the THIRD law. second, when opposite forces work, they work on DIFFERENT bodies, not in the same. If you run, you are kicking the ground with your feet, and the ground push you with a force with the same magnitude, but upwards.

>>6917728
>And "dimensions" obey a certain relationship to "not dimensions".
What is a "not dimension"?

Is the universe causal? Is everything that has happened and will happen predetermined?

>>6917728
Is it even possible for science to describe reality as it is? Does it need to?

>>6917738
Food is a dimension in the system of breakfast. When you're talking about the dimensions of the universe it would be a good idea to differentiate between spatial and time dimensions. Just stating that time is 4th dimension makes you look reallly retarded.

>>6917742
>Given the state of a system at some time, the laws of nature determine the probabilities of various futures and pasts rather than determining the future and past with certainty.

why is there a standing wave and over all emission between two DBR-mirrors when the first DBR mirror should already reflect like 99.9% of the incoming light?

Time is not a dimension. X, Y and Z have relationships to each other that we define as 3D. Movement of energy through matter within that spatial relationship gives us that 3rd dimension, time is a measurement of the change of that system.

>>6917746
meant for >>6917728

>>6917756
Spacetime is a 4-dimensional pseudo-Riemannian manifold with signature (1,3). The first dimension of spacetime is time. Get the fuck out of here, you fedora'd underaged sermonizer of anti-intellectualism and stop spreading ignorance.

>>6917760
>In GR we do indeed disregard "time". It is useful to do for certain calculations. So, I am not exactly sure what problem Barbour has, but indeed we can and do disregard time if need. Maybe, there are other "systems" that could be better modeled without time (like GR)

yep, i will F off.

>>6917756
space-time is a dimension..
thus proving that time is a dimension..

>>6917760
couldn't have said it better

Sorry if this question is too rudimentary. The other in class the teacher explained to us how natural magnets get their magnetic field and how we make electric generators. I was wondering since all atoms have an E field and are constantly moving due to heat why isn't there a current in everything? Actually, I think I'm asking why isn't heat vibration generating magnetic fields if the molecules have E fields.

Time is just a fundamental parameter in every acceptable configuration space used to model an evolving physical system.
The configuration space is roughly the set of all the numbers you need to completely determine the status of a system. In theoretical physics, the state of the system, to be defined properly, always needs to have time specified. In this last phrase, 'time' is just what you measure on a clock, just as length is just what you measure on a meter. As long as this tools completely rule out a certain configuration, you are fine.
Then in more advanced theories you have intricate relations between this 'time' and other 'dimensions', but this does not change what these things are.

>>6917725
>yin-yang

Yes, positive and negative charge are one entity. That is why physicists just speak of "charge". Only in high school do you really care about the "-" or "+". The notions of "+" and "-" are just artificial labels we put on things to make the math simpler. We didn't have to do that. It is just a "labeling" convention.

What we really have is a "quantity" we can measure. We can put the "0" anywhere we want, and we can "space the tick marks" anywhere ever we want.

>Is the total sum of charge in the universe is 0?

That is meaningless and trivial question. Because 0 is just a naming convention. We can put the 0 anywhere we want! We could measure all the charge and call it "1"!

An actual important question is; "is the total charge of the whole universe conserved?" Ie, if we measured it and called it "1", would it still be "1" later?

The answer is we really don't know. We end up getting this weird semi-related problem with charge when we start doing article physics. There is this thing called "C-symmetry" that doesn't seem to work the way it should! Charge gets all kinda of fucked up when dealing with the "weak nuclear force".

Could you elucidate us on the proposed granularity of space time? What are the gains? What is between them?

>>6917182
hi physics guy

Thanks for answering the question on supersymmetry.

Does the cancelation (leading to a low mass) take place because when you compute the quantum corrections to it, having many (supersymmetric) partners means that in the pertubation expansion I will take them into account "at the same time" and then some signs flip so that the value stays low?
Alla geeting a factor
1+a+b+(-a)+b^2+(-b)+... \sim 1+\epsilon
where apriori many terms are there, but then actually not?

Secondly, do you have some list/classification of supersymmetric theories?

Lastly, if you're still at cern, what theories do people there definitely consider to be ruled out by now?
Especially regarding the (formally) popular candidates.

>>6917746
>>6917756
Listen kids. Science is quantitative, and needs precise definitions for concepts, hypotheses, and theories. So, we actually have to "codify" what we want to call a "dimension" mathematically. It isn't just based on your fucking feels.

We took the properties of our "three dimensions" and used them to form a category called "dimensions". It was then noticed that "time" also fits this category, because it fit the criteria. Hence, time is considered a dimension.

This is really really really old news. It was done over 100 years ago at least. It is very standard physics by now. If you want to throw a fit that it is wrong, your a century to late.

Furthermore, by classifying "time" as a dimension, we have been able to make great leaps in physics and technology. Countless technologies are built which incorporate the notion that "time is dimension", including GPS and your computers (even EM + Basic Reality count time as a dimension). They are testaments to the validity of the idea.

What is symmetry/supersymmetry?

>>6917806
Hi Anon

>>6917860
go on wikipedia before you ask such a general question. Then -maybe- come back with a proper question.

http://en.wikipedia.org/wiki/Symmetry_%28physics%29
http://en.wikipedia.org/wiki/Supersymmetry

>>6917856
Don't you think that time works better as parameter than a dimension?

>>6917856
>It was then noticed that "time" also fits this category, because it fit the criteria.
So what is this criteria then?

>>6917874
>Don't you think that time works better as parameter than a dimension?

No. And those are not mutually exclusive things.

In babies first physics time is just an independent variable.

However, in more advanced physics, it becomes overwhelmingly evident that time should be treated as a dimension.

And in other areas of advanced physics, time is not an independent variable at all. It is just a dimension and it is a function of some other independent variable. Just the the other three dimensions are.

Recent findings suggest that superdiffeomorphism algebras in a n-dimensional TQFT give rise to an unforseen framework for solving decay constants. One can use Toda CFTs to classify superconformal symmetric effects, and conjecture that a (p,q) 7- brane wrapping a T^n at the intermediate scale can be incorporated into representation theory on an ALF space of Spin(1) holonomy. Is this a possible approach to compute Barnett-Langan invariants in a topologically twisted perturbative matrix model of conical singularities in the formulation of the NMSSM?

Thanks for the questions Anons. I got shit I go to go do now.

I might be back later to answer some more questions and/or answer some of the ones I missed. That is, if they aren't too fucking retarded.

>>6917653
Why did you attend philosophy classes? Was it compulsory? Did you learn anything useful from it? Would you suggest to go there your friend? Your mother?

>>6917904

>>6917904
>Barnett-Langan invariants

Do people actually say "Spin(1)" holonomy? What'S your n?
Also, how would a method to compute numbers from a TQFT help you with a supersymmetric theory on a physical (hence metric) space?

My advisor actually does phenomenology in perturbative matrix models now, but I don't recall that being supersymmetric.

>>6917904
>Barnett-Langan invariants

Do people actually say "Spin(1)" holonomy? What's your n?
Also, how would a method to compute numbers from a TQFT help you with a supersymmetric theory on a physical (hence metric) space?

My adviser actually does phenomenology in perturbative matrix models now, but I don't recall that being supersymmetric.

>>6917924
>>6917928

Loool look at this autist deleting his whole post only because he made a slight mistake in the last sentence

>My adviso(e)r actually does phenomenology in perturbative matrix models now, but I don't recall that being supersymmetric.

What a fucking pathetic beta faggot.

>>6917936
how do I into alpha mode?

>>6917936
Aren't both spellings equally valid?

>>6917950
>how do I into alpha mode?

Jesus Christ, this shameful disaster is getting wrong with every post.

>>6917958
That's what underlines the beta.

>>6917904
Yes, but only if x=2

what's the thing called where you run electricity through a coil, and then it makes magnets move around on the outside

Describe to experiments which show that atmospheric pressure is very large

>>6917681
>What if a person was pushing the rock with the strenght of his muscles. Then resting, then pushing again, and so to infinity.

Use a heavier fencepost so it pushes with the same force as the guy. If it isn't enough to move the rock, it'll still be there in a year, applying the same force.

>Would the person move the boulder eventually? Does it move it a little bit with each push? And if not, where does this "pushing energy" go?

Assuming he's applying less force than static friction, no, it will not move eventually and does not move a little with each push.

"Pushing energy" is not a thing, but I understand you now because I asked the same question of my teacher in high school physics class:

>Hey teacher
>If W = dK = F dx, and you don't move (so there's no dx), then there's no Work being done.
>Yet I still get tired from holding my arm straight out, clearly expending energy.
>Where does this energy go, if I'm not moving my arm up or down?

And the answer is: Ask a biologist, but the short, wrong, answer is that you're moving all the time, shaking a little, pushing blood around etc.

>>6915968
What constitutes a retarded question?

>>6915968
I want to design a system of some kind that will photodissociate isolated diatomic molecules. I began by looking at Einstein's treatment of absorption and emission rates, molecular orbital geometry, the Morse potential and various other topics.

I'm not sure how exactly to tackle this. It seems like all the stuff i've looked at is useful but im not sure where to go from here. I first want to look at the case of an individual molecule and what wavelength of photons needed to dissociate. Also, how do i know the electrons will absorb these photons? Why not the nucleus? After i figure out the theoretical case for one molecule, im confident in my ability to apply stat mech but i'd appreciate advice on this anyway.

>I have a B.S. in physics (honors quantum and E&M), in case you're taking into account my education

>>6917910
>Why did you attend philosophy classes?

I've only taken taken 3 philosophy classes. Intro to phil, logic's, and philosophy of science. All were my choice.

I appreciated and understand the importance of the topics and ideas discussed in intro and logics. They were probably some of the best (non physics/maths) course Ive eve taken. And I can honestly say that they have made me a better scientist. I would recommend them.

However, philosophy of science was a complete crock of shit. I was under the impression that it would be a discussion of some of the possible philosophical implications of certain scientific theories and some history. But it wasn't. Instead it was faggy phil majors with no fuck grasp pf science, reason, or math, arguing over semantics with their fucking feels. I felt like I was surrounded by fucking retards with no grip on reality. Worst class ever! It could have been just a shit teacher though.

>>6919368
yeah, anyone who wants to discuss the philosophy of science should be very well-read on science and have practiced it themselves. when shut-ins try, it ends miserably

>>6919368
Also, it's probably 100% that you totally misunderstand many of the arguments made on science

David Hume's arguments are very convincing, but most people don't understand them at all

>>6918142
My best advise would be to search the "current literature". There already seems to be "theories of photo-dissociation for diatomics ... " out there. Maybe what you want is already done, or maybe you can just take a similar theory and extrapolate it as needed. Then again, maybe you already looked for this?

I don't think you should try to re-invent the wheel.

Examples:
http://scitation.aip.org/content/aip/journal/jcp/79/12/10.1063/1.445788

http://onlinelibrary.wiley.com/doi/10.1002/ijch.199000002/abstract

>>6917195
I'd so want to see that. Where do you think CERN will be at in 2024/2025? What about the LHC?

>>6919394
>probably 100% misunderstood the arguments
>David Hume

Hume was never mentioned in the class. Neither were any other straight up "philosophers". The class only talked about modern "scientists" and "science". And the arguments weren't complicated. They were just mindless bullshit.

I shit you not, but one class was literally a some faggy phil major yelling about how electron was racist because it can only be "+1/2" and "-1/2" spin! He kept insisting that It should be allowed to spin however the fuck it wants, because of equality and his fucking feels! He argued with the prof for a fucking hour. It was like watching two retarded children grunt at each other. And at the end the teacher conceded that "maybe the electron was racist"!!

I took the class with a couple of buddies (two physics and one math major). And we jointly went the the physics department chair to complain about the class mid-semester. He completely understood and basically told us that the majority of philosophers are fucking morons arguing about nonsense. He jovially said the class would be a lesson on how to deal with idiots without murdering them.

However, I want to make it clear that my other two phil courses were great. Especially my logic course. The proof in that class is one of the smartest men I have ever met, and his ability to understand and explain logic was superb. I wouldn't even consider him a philosopher, he seemed more like a mathematician too me. His arguments were meaningful, because he could back them up mathematically, logically, and rationally. As opposed to the majority of modern philosophers that just rant about their fucking feels and argue about nonsense.

>>6917627
>Conservation of energy
>derived and only applies to certain kinda of spaces.

Mind. Blown.
Any layman understandable article I could read on this?

100% best thread on /sci/

>>6917627
>No. There is no conversation of energy (the way you are used to it) when space stretches in that manner. Conservation of energy is not a "first principle". It is derived and only applies to certain kinda of spaces.

Is this kinda like saying that the photon's "energy" in its inertial frame remains unchanged, because the amount that the space has dilated, matches the shift in wavelength?

Or am I totally misunderstanding this?

(BTW i'm not the guy who asked)

>>6919422
CERN and the particle physics/nuclear physics community at large is always planning the "next big machine". There are official meetings (some of which I have attended), inter-national committees, and all sorts of fancy pants official shit being done to prepare for "after the LHC". The LHC it self was planned and officially approved way back in 1994!

I think the current plan is to have a new machine (upgraded LHC) in ~2022. And then another one in ~2032. We are planning for them both already.

Plus we got some other cool experiments in development/planning stages. CERN isn't just the LHC, we have a lot of other shit. I would like to say more, but I think it might be privileged info. Sorry Anon.

>>6919441

I get the feeling your are afraid of your feels.

That said, hot damn. I hope someone keeps you warm at night.

>>6919476
Thanks, m8.

>>6919496
I really want to make a '>tfw no gf' joke, but not sure if PT's married/in a relationship or not.

Are you married/in a relationship, PT?

>>6919447
>Any layman understanding article

Probably, but I couldn't find anything. The closest thing I got was: http://www.sjsu.edu/faculty/watkins/noetherth.htm

Let me digress though: Ask yourself, why give a shit about energy, momentum, etc in the first place? Why did we decide those were "useful quantities"? ....Because those quantities are usually "conserved". A conserved quantity is extremely helpful, because we can actually get quantitative truths about the universe. We get "anchors" of truth. And if your are clever enough you can tie other concepts and measurements to those anchors. In that way you can use your current measurements and some anchors of truth, to predict the future or past or whatever.

The "conservation is energy" is derived from a "time symmetry". In this sense, conversation of "Energy" is a sort of "side effect" of certain configurations of time. When energy isn't conserved, we can still use it and measure "energy" , but it isn't an anchor to truth now! So it is just another faggy parameter like position, that ends up being (hopefully) a function of some greater underlying mechanism. The mathematician Emmy Noether was the first person to make the connect between "conversation" and "symmetries". She is a fucking legend.

FYI:
Conservation of momentum comes from "space symmetry", Conversation of electric change comes from "gauge symmetry". All conservation come from symmetries.

http://en.wikipedia.org/wiki/Noether%27s_theorem

How can one find out stuff about the cosmos by studying relation between Luminosity distance and redshift?

>>6919496
>I get the feeling your are afraid of your feels

Nope. I think my feels are fucking fantastic Anon. Emotions are a vital part the human experience. I actually love dramas and shit like that.

The only problem I have is when people use "feels" as a replacement for objective coherent rational arguments. When people cannot differentiate better subjective and objective arguments. It is annoying as fuck and has no place in science or mathematics. It is retarded.

>>6919496
>>6919506
I actually have a couple of gfs. I don't like the idea of being "settled down". Fuck that shit.

Maybe when I get older. Right now I'm still "sowing my oats". And I'm having a damm good time.

>>6919556
God has blessed your life, m8.

Captcha: Mosques

>>6919460
You are kind of misunderstanding it. see >>6919527

In GR, if I straight up wanted to use the quantity we usually call "energy" it wouldn't be helpful at all. It is not conserved and gives no meaningful insight into anything.

However, we can find other quantities that are useful. We could get this "energy-analog" thing (sometimes just called energy). However, even the "energy-analog" is not necessarily conserved either. It is decreasing in a expanding universe, increasing in a contacting universe, and constant (conserved) in a static universe.

Why? Because in a expanding/contacting universe, the global time symmetry is all fucked up. The universe is "changing size" as a function of "time", which destroys the symmetry.

>>6919460
Also, a photon doesn't have an inertial frame

If we tried to construct a "photon frame", we find out that time doesn't exist to the photon and everything happens to it at once.

This is a consequence of photons being light, aka they travel at the speed of light.

What is the meaning of life?

Would you rather identify as a nerd or a geek?

>>6919598
I thank you for your sentiment Anon. However, like the overwhelming majority of physicists I am an "agnostic atheist". And this "blessed" thing is kind of offensive and disrespectful. Why you ask?

I got to where I am in my life and have my relationships I have, because I made a conscious effort to work for the shit I want. I got off my fucking ass an tried to build the life I wanted. It wasn't just sheer fucking chance and I wasn't the super-natural. It was me. My actions. My life. And to attribute my hard work to the supernatural, is kinda fucking offensive. If anyone has blessed me, it was me.

That being said, I really don't give a flying fuck what religion or magics most people believe in. Do whatever the makes you happy.

Do you watch TBBT? Who's your favorite character? Mine is Sheldon.

>>6919600

>OP is a cool guy

>>6919606

Right, I guess that was dumb of me to say. I was actually talking to one of my physics profs today, about how when you try to solve for the proper time experienced by a photon travelling a finite distance, you wind up dividing the observed time difference by infinity, which gives some infinitesimal quantity. He basically said the same thing, that:

>photons are essentially immortal

Which struck me as batshit insane: that those bastards just keep reflecting and refracting all over the place for all of time.

Question:

What exactly is happening when a photon is "reflected and refracted"? My understanding (which is probably wrong) was that reflection is Thompson scattering between an atom and a photon when it hits the interface.

What about refraction then? Is that another photon being emitted by the atom due to the scattering? How does bi-refraction fit into this?

>>6919621
Dude lay of The Atheist Experience for a second. He expressed a phrase you sperg.

Did you know that Einstien was a jew?

>>6919654
Remember kids EINSTEIN was a JEW and thus an entire race can do no wrong. REMEMBER THE HOLOCAUST if you criticize our blatant corruption you are Nazi scum.

Any plans to improve the LHC since China is making a bigger one?

Alright, if you're still here.

I'm a physics student but my interest is in mathematical physics.

I can't do it. I tried already and I don't have the relevant mathematical background. I can't just "make it up as I go along" or "improvise" and learn only the 100% necessary mathematics like most physics students seem to.

To be able to do something I must first understand the mathematics fully. I don't have time to do this with my current degree, so I'm going to drop out and take the 2:1 BSc in Physics with Theoretical that I would have got last year.

Can I apply for some sort of masters program and combined with using the rest of this year to self-study mathematics, catch up to do mathematical physics? Perhaps in Cosmology or Particle physics or some other similar field.

The thing is I have self-doubt because I did badly in my particle physics class last year. They presented a load of bullshit at us out of nowhere. They never taught us group theory but they're spouting all this group theory like its obvious. I tried learning some myself but didn't get very far. All my peers seemed happy to just rote memorise all the junk they were fed like "blah blah comes from the unitary SU(2) group and..." but they don't even know what they're saying. It's like a foreign language to me. So I did badly because the previous years I only did well in exams by learning the fundamentals, but in particle they were completely inaccessible to me.

It's like this with all advanced physics topics. So I got overwhelmed by the amount I don't know and lost motivation this year.

>>6915968
What's the logic behind 'faster than light travel means to go back in time'?

>>6919630
>just keep reflecting and refracting all over the place for all of time

No, not in way you are trying to talk about it. Your "scope" is zoomed out. "reflected" and "refracted" are ultimately emergent statical properties. You need to zoom in to the actual "particle interaction" level. Aka Quantum field theory. These are written out in diagrams called "Feynman diagram".

http://en.wikipedia.org/wiki/Feynman_diagram

So, "fundamentally, how does a photon interact with the other particles?"

Well, photon interactions contain 3 particles (including the photon); Photon, Particle A, and Particle B. Also, A and B cannot be a photon. Note: There are many other constraints on A and B, but we can ignore those for now. So with basic combinatorics we get all possible interactions classes:

1) Photon + A - > B
2) Photon + B - > A
3) Photon -> A + B
4) A + B - > Photon
5) A -> B + Photon
6) B -> A + Photon

So you can see a photon is not "immortal" in the sense you mean, because there is never an interaction with a photon on both ends. If there was, "perhaps" we could try to say it is the "same" photon on either end. However, we can't even make it to that case.

So, how the fuck does the photon traveling look?: Photon1 -> A1 + B1 -> Photon2

And reflection/refraction: Photon1 + B1 -> A2 -> B3 + Photon3

Those are the "fundamental" things the photon is doing. However, this matter is complicated even further, since we are dealing with quantum particles. Meaning the photon doesn't just take one "path". It takes the averages of all possible allowed paths over all possible space-time simultaneously. From there we get statical values, which directly correspond to our observations and these properties you call "refraction" and "reflection".

>>6919710
>Any plans to improve the LHC since China is making a bigger one?

Yes, we have plans to improve. They will be done regardless of what China does.
see >>6919476

>>6919621
I'm >>6919598. Read: >>6919651.

I'm an agnostic as well (Strictly agnostic. Not theistic nor atheistic), but that was just a fucking phrase used by everyone to say that the next person has had a good experience or such. It's like saying "Go to hell". I don't believe in hell and think the concept of hell in itself is immoral and unethical, but I still say the phrase because who gives a shit.

I understand how you and the next person on /sci/ feels about your achievements and how you cherish them and shit, but please stop being such a shitlord and take a compliment however it is expressed. If an old lady said "God bless your soul" after you helped her with some shit, you ain't gonna lecture her about how souls are illogical and uncalled for, and thus we should assume they don't exist. Or about how organized religion is immoral and flawed and thus we shouldn't believe in them. You'd nod your head thanking her, and maybe even say "You too" or some other shit so that you can feel better and make her feel better as well.

That being said, so long as there's no one forcing a dildo of his beliefs up your ass, there's no need to talk about shit unless it's a debate from the beginning. Who gives a shit what flying daddy the next person believes in if it doesn't hurt you.

>>6919757
>I'm agnostic
>I tell people "God blessed your life"

Nice contradiction

>>6919619
Fuck off back to Leddit or geeklife or whatever other shit you came from. People here identify as scientists, more specifically what they specialized in. The whole geak/nurd culture is poisoned with wannabe STEM fedora tippers that have reached an ubermensch state of euphoria.

>>6919654
See: >>6919690 and >>>/pol/

>>6919757
>If an old lady said "God bless your soul" after you helped her with some shit, you ain't gonna lecture her

Why not?

>>6919368
>I appreciated and understand the importance of the topics and ideas discussed in intro and logics. They were probably some of the best (non physics/maths) course Ive eve taken. And I can honestly say that they have made me a better scientist. I would recommend them.
>However, philosophy of science was a complete crock of shit. I was under the impression that it would be a discussion of some of the possible philosophical implications of certain scientific theories and some history. But it wasn't. Instead it was faggy phil majors with no fuck grasp pf science, reason, or math, arguing over semantics with their fucking feels. I felt like I was surrounded by fucking retards with no grip on reality. Worst class ever! It could have been just a shit teacher though.

I had the same experience. I took babbys first philosophy in High School (dealing with the greeks during the autumn semester and then moving swiftly along to modern thinkers in the spring semester) and it piqued my interest seriously. Then in Uni, I took a (mandatory for my degree) course on the "Scientific Method" and it was straight crap. With few exceptions, there were zero insights offered that weren't either obvious or irrelevant, and the few that were worth something, I'd read about elsewhere.

>>6919757
>God bless your soul is a common phrase

Nope

>>6919765
It's a figure of speech you shitlord. I don't live my whole life fearing people picking on me because I have not transcended to be an ubermensch like them cause I still use some phrases involving theistic beliefs to describe things.

If you read anything beyond the first two lines of my post, you might've actually understood what a shitlord you're right now.

If you're still insisting on your ideology that such figures of speech shouldn't be used if you're an agnostic, I recommend you read Ricardo Dawgin's book, The God Delusion. It's a magnificent piece of philosophy that gives out some great arguments for why Christians, Muslims and Jews are all retards that should be killed for the betterment of humanity.

>>6919770
Look up

>>6919779
Let's say it's unpopular, does that condemn it as a cursed phrase that shouldn't be used at all by anyone that is above those peasant gnostic theists?

>>6919757
You are the cancer of /sci/

>>6919765
>>6919770
>>6919779
>>6919788
Didn't realize /sci/ was plagued by this many euphoric atheists. I tip my fedora to you, my fellow independent thinkers.

>>6919787
Nice straw man

Where did I mention the religion or worldview I followed?

>>6919794
I'm sorry that offended you. Nonetheless, my argument stands.

>>6919787
>PG politely explains why he didn't like you comment but appreciated the thought

>You get BUTT-HURT

Jesus fucking Christ you're pathetic

>>6919796
>implying you have an argument

Look at what you wrote

>>6919798
I don't think >>6919765 was PG. My original reply to PG was >>6919757, which didn't contain this sense of 'butthurt' you're talking about.

>>6919800
Looks like you have one. A very well thought one as well.

>>6919757
>>6919787
shitposter plz go

/b/------------>

>>6919802
>implying your whole post isn't drowning in BUTT-HURT

0/10

>>6919757
>decent thread
>fucked up by one idiot

Nice job shit-posting moron

>>6915968
What is the value of current I in a circuit as shown on the picture but with a DC supply instead of AC. Does the current I have a constant value during charging or not?

>>6919757
I fucked your mom in the ass.

*It's a common phrase

>>6919813
>What is the value of current I in a circuit as shown on the picture but with a DC supply instead of AC. Does the current I have a constant value during charging or not?

Time dependent. Assuming ideal components, it starts at infinite, and goes to zero as t goes to infinity.

>>6919966
>Time dependent. Assuming ideal components, it starts at infinite, and goes to zero as t goes to infinity.

Oh, and: Assuming real components: It starts at (V_DC/R_Circuit) and goes to the leak current of the capacitor.

Could you explain the role of representation theory in particle physics?

I heard that particles are identified with irreducible representations. How does this work? Why is it done like this?

If I sit down on a chair and pull up on the seat, will I be able to fly?

explain R, S and T phases to me

If you feel so good about yourself, why do you like so much to bash on pure mathematics
(more in other threads before)?

>>6919966 Thanks, and is there a graphic representation or a mathematical formula showing the change of I during time t ?

>>6919793
Indeed.

>>6920036
>>6919966
>Thanks, and is there a graphic representation or a mathematical formula showing the change of I during time t ?

Assuming ideal components, the current is infinite for an infinitesimal period of time, then zero.

With real components, you need to know the resistance of the circuit R. Then:

I(t) = 1/(e^(t/RC))

And it gives a classical exponential falling curve towards zero.

>>6919757
You're a pathetic excuse for a human being.

>>6918067
It's just a way to say he is mediocre.

>>6919757
>Strictly agnostic

This is not a valid position. Either you believe or you don't. There is no third option.

>>6919757
You are the reason we can't have nice things.

>>6919787
Satan fucked your sister.
*its a figure of speech faggot

I like physics guy, please stay physics guy.

>>6922326

>>6922487
Wow someone is mad, no?

Possibly ( probably) a stupid question but, Is there any proof that time is tangeable? I mean how do we know it's not just a force like gravity in that there is no possible way to travel back in gravity.

>>6922428
That's some shitty logic, acknowledging that you don't know the answer to a question instead of guessing the answer isn't an invalid view point.