/sci/ - Science & Math

>>2669924
enthusiastic bump
I want to know also

>>2669924
>implying light has no gravity
Retard.

Photon = Energy

>>2669926
because in general relativity mass isn't pulled by gravitation. mass is only responible for the resistance against a deviation from the path defined by gravity (i.e. since light is massless, it's very easy to change it's direction, whereas it's difficult to change the direction of a heavy object)

go to wikipedia for "Geodesic"

>>2669924
According to relativity, gravity is not just a force but a result of distortions in the shape of the universe

light does have mass. its just two electrons moving at the speed of light. one happens to be moving int the opposite direction in time.

>>2669942
>wikipedia

So in laymans terms, light bends at high gravity points because space bends at high gravity points?

I ask because I was reading A Briefer History of Timer and didn't understand the part about geodesics.

>>2669949
what wrong with that?
are you implying information from /sci/ is more accurate?

>>2669924


Because gravity curves spacetime and light follows that curved path.

>>2669948

This is bullshit of course.


inb4 relativistic mass, which does not exist.

>>2669961
irrelevant comparison fallacy
Wikipedia is not a source.

>>2669948
Troll.

Also, with mass-energy equivalence in general relativity, light does have mass, it just doesn't have rest mass since there is no reference frame in which it is moving.

Qualifications: 1 semester GR. (As if qualifications meant something on the webz lol.)

>>2669960

No, not light bends. Light just follows the bent path, so from the light´s point of view it just flies straight forward.

>>2669968

Yeah I think I get it now, like a metro car, it doesn't turn, the track turns, it just keeps going straight from it's perspective, kinda.

>>2669962
>inb4 relativistic mass, which does not exist.
Star Trek moron detected. You can't go faster than light.

>>2669972

> in general relativity, light does have mass

Nope.

> there is no reference frame in which it is moving

I see light moving.

Got a lot to learn, man.

E = m/sqrt(1-v²/c²) * c²

->

m = E/c² * sqrt(1-v²/c²)

this is true for all frames of reference. Since we measure light having v = c at all frames, we get the answer if we substitute v = c:

m = E/c² * 0 = 0

No mass in all frames.

>>2669978

lolwut?

> implying i said anything about going faster than light.

high gravity points?
it's like this:
> there is energy (mass density, electromagnetic density, whatever)
>therefore by the "Einstein Equations" (again -> wikipedia) space is curved - curvature of spacetime is just what gravity means
>therefore everything is following curved paths (mass, light, ...everything)
>if something is massive and you push it, it will resist (if you take a book in your hand it's heavy because it wants to follow it's path which is downwards - it's just heavy because you push it away from its path)
>light is massless so it easily gets deflected

>>2669972
Somebody post this man a facepalm image.

>>2669980
>I see light moving.
That's in your reference frame, moron, not the light's.

>>2669924
light travels along contours in space-time. Contours in space-time are created by objects of mass. These contours are what cause the apparent attraction between two objects of mass, otherwise known as gravity.

>>2669990

Light does not have a rest frame of reference. It´s always c.

>>2669986
Mass increases with velocity you moron and becomes asymptotic as you approach lightspeed. You can't go faster than light, no matter how much you wish for it.

>>2669995
Which is exactly why light isn't moving in any reference frame.

>>2669987

wouldn't that make it's suceptability to the effects of gravity infinite?

>>2669996

> Mass increases with velocity

lololol back to school. Mass is an invariant.

Velocity-dependent mass was a concept from BEFORE relativity was developed. It is bullshit. Just forget it.
Even Einstein said it was pure shit.

for all the people who say this >>2669948 is "trolling"

note this, the only observation supporting relativity and supposed to deny the property of mass to light is the curvature of light around astronomical bodies(originally mars if i remember correctly). this curvature is said to be larger than one would predict for a SINGLE electron mass. PROVE this curvature isn't EXACTLY what would be predicted for TWO electron masses.

>>2669999

You contradict yourself.

Light does not move, therefore it moves?

>>2669980

Light does have mass. Not rest mass.

And I meant there is no reference frame in which it is NOT moving. Fuck.

>>2670004

You´re still wrong. See:

>>2669980

You are using Einstein´s formula incorrectly.

>>2670001
If special relativity is wrong about mass increasing then why dont particles move faster than light when theyre accelerated? Oh right because YOURE A MORON.

>>2670002
not doing your GR homework for you.
>>2669970

cry more.

>>2670014
I'm not the one claiming that mass is immune to gravity.

>>2670013

Dude, relativity does not make ANY statements about mass changing. It only gives a new meaning to time and space. Your teacher has no idea of physics if he taught you this mass increasing bullshit.

Because their energy is too high, derp.

Why are you ignoring my calculation of light´s mass? Who is the moron now, huh?

back2school

Guys.

E = mc² is the formula for the frame of reference in which the observed body RESTS, meaning that here v = 0. Light does not have this frame of reference, it is always moving. Therefore, you have to use the correct formula

E = m/sqrt(1-v²/c²) * c²

which is correct for ALLL frames of reference.

lrn2relativity

>>2669970
>wikipedia is not a source
At best you can say wikipedia is not an accurate source. But if you were to say that you would be lying according to studies.

http://news.cnet.com/Study-Wikipedia-as-accurate-as-Britannica/2100-1038_3-5997332.html

this isn't HW, no one hear has ever answered the very real question posed here >>2670002

you're a bunch of high school slackers, too lazy to look at a real question

>>2670024
Yeah try citing an encyclopedia in a paper and see how that goes over. Not a source.

>>2670021
Look you can deny it all you want but when people try to push things faster than light they dont keep accelerating, their acceleration goes down because their mass goes asymptotic. You can't have a warp drive, stop herping.

these threads really confuse me

how can you people argue about scientific fact?

there's only one right answer, and all you have to do is go look it up and there you go. No need to get all pissy about someone else's, or even your own, misunderstanding of the physics.

>>2670027
If light has any velocity then wouldn't its velocity be zero at some point during a reflection?

>>2670037

> when people try to push things faster than light they dont keep acceleratin

Correct.

>their acceleration goes down because their mass goes asymptotic

Bullcrap. Seriously.

> You can't have a warp drive, stop herping.

> implying i said that.

>>2670043

No. Velocity has a length and a direction. If you change the direction it does not necessarily have to decrease and increase again.
In the case of light, just the direction of the velocity is changed.

note this, the only observation supporting relativity and supposed to deny the property of mass to light is the curvature of light around astronomical bodies(originally mars if i remember correctly). this curvature is said to be larger than one would predict for a SINGLE electron mass. PROVE this curvature isn't EXACTLY what would be predicted for TWO electron masses.

light has the mass of exactly two electrons

>>2670032
I think you mean

"no one on this goddamn website has any fucking idea what the shit he is talking about"

none of you are theoretical physicists, stop arguing about this shit that you've read about on wikipedia or had a class on in your AP Physics class.

>>2670033
Doesn't change the fact that Wikipedia is about as accurate as Britannica when it comes to SCIENTIFIC articles.

That makes it MORE than a reasonable source to use here on /sci/ (in case you didn't know /sci/ is SCIENCE and math)

>>2670037

Suck this:

http://arxiv.org/abs/gr-qc/0009013

>>2670042
>lets all do the opposite of science

>>2670044 makes an excellent point. When things approach the speed of light, their acceleration decreases even if the force is the same. Since the force is the same, their mass is getting higher.

>>2670049

I think you are wrong, Mr.

>>2670053

Your reasoning is wrong. It is not mass that is the reason for not being able to accelerate particles to speeds higher than that of light, it is energy.

I bet you are one of those people who think light slows down in matter, right?

>>2670052
Yeah maybe your magical exotic matter doesn't increase in mass as it approaches lightspeed. But guess what idiot, your exotic matter isn't real, everything that's made of real matter gains mass.

>>2670044
I was taught that the lorentz factor causes the mass of an object traveling at velocities near the speed of light will increase. Mass dilation, just like time dilation.

or in other words: relativistic mass = resting observer's mass times the lorentz factor

If this is incorrect please explain why in more words than "bullcrap" or "it does not exist" If Einstein himself thought it was baloney, then why was I taught that? I'm not trying to use some kind of logical fallacy here, it's a legitimate question. Why would I be taught something that was believed to be false?

>>2670051
>implying that this thread is science and not a bunch of trolls

Do all threads on /sci/ devolve into arguments about faster than light travel?

>>2670060
It's mass that keeps objects from accelerating not energy. Fucking idiot. Go back to junior high where you belong.

ITT NO ONE KNOWS ANYTHING; EVERYONE KNOWS NOTHING

>>2670061

Here: https://www.worldscientific.com/phy_etextbook/6833/6833_02.pdf

Maybe you believe members of the russian academy of science?

You are talking bullshit, man. Mass is invariant.

>>2670069

yes :[

>mfw

>>2670065

No. In relativity only time dilation and length contraction exist. Mass is an invariant.

For a copy of Einstein´s letter see https://www.worldscientific.com/phy_etextbook/6833/6833_02.pdf

I´d rather see you explain why mass is supposed to change with velocity.

I think i´ll do an explanation tomorrow in form of a new thread about this topic. I´ll teach you some relativity.

>>2670074
nice one

>>2670071
IT is momentum that is effected by velocity. Einstein didn't like the idea of relativistic mass.

>>2670071

I work in the physics department of a well-known university on deriving a limit for the graviton mass from fixpoint quantum gravity.

What now, bitch?

If you are so confident, explain to me why mass increases with velocity? Why?

>>2670084

Nothing will happen. Shall i upload that paper somewhere else? it is really good.

>>2670081
I don't know why mass is supposed to increase with velocity other than that is what I have been taught. If I can't trust my educators, then why should I trust a stranger on the internet? At the moment I am unsure of which to believe. I think this matter will have to rest until I actually take some college courses regarding special relativity.

what is fixpoint quantum gravity?

>>2670081
It doesn't matter what you think Einstein or anyone else thought you moron. If mass didn't increase with velocity particles would easily reach speeds faster than light. But they dont you imbecile.

>>2670093
Momentum

>>2670091

Ask them why. They can´t answer anything other than "I don´t know, because when we look at E = m/sqrt(1-v²/c²)*c² we can say that m(v)=m/sqrt(1-v²/c²) lol" without any reasoning.
Assigning bodies a mass that depends on the frame of reference is unnecessary and stupid, as it is not a mass anymore.

>>2670093
I think that there is another reason why particles don't reach the speed of light that doesn't have to do with the idea of relativistic mass. Our friend anon here never suggested that it was possible to accelerate to the speed of light, simply that relativistic mass is a false concept.

>>2670093

No they wouldn´t, idiot, as it was said multiple times before. Mass is not the reason, energy and momentum are.

If you don´t believe me just shut up and live on with your false beliefs.

>>2670098
That reason is conservation of momentum.

Where momentum = m*v*(lorentz factor)

>>2670098
>>2670095

Thank you.

>>2670109

Actually, momentum is a four-vector. But basically, you´re correct.

http://ajp.aapt.org/resource/1/ajpias/v77/i5/p430_s1?isAuthorized=no

>>2670091
It's all stupid semantic bullshit. Here's what you need to know:

If you define mass as a constant independent of velocity, then
<div class="math">F = \frac{d \left( \displaystyle{mv \over \sqrt{1-v^2/c^2}}\right)}{dt}</div> where m is mass.

If you define mass as varying with velocity, then
<div class="math">F = \frac{d(mv)}{dt}</div>and
<div class="math">m = \frac{m_0}{\sqrt{1-v^2/c^2}}</div> where <span class="math">m_0[/spoiler] is the mass at v=0.

If you know how to do math, these are obviously the same.

>>2670126

Or, like Newton did it

F = dp/dt

Your second formula leads to a wrong equation of motion.This is why kinetic mass was abolished.

anon who was against mass increasing with velocity: it is easier to attract flies with honey, rather than vinegar

>>2670131

Sad but true.

Girlfriend called. I´m out.

>>2670002
why don't things get negatively charged when light shines on them?

>>2670131
no it's not, have you ever tried that experiment?

those who say light has no mass, what rules out the possibility of the photon (assuming you believe in photons) having a miniscule amount of mass that is negligible for nearly all calculations?

>>2670053
>>Implying Newton's laws are valid at velocities near c.

To the rest of the people in this thread:

Photons never accelerate. Photons ALWAYS, ALWAYS, ALWAYS move at c, ALWAYS, ALWAYS. Everything in the electromagnetic spectre ALWAYS travels at c. This includes microwaves, radio waves, X-rays, UV-rays, infrared waves, etc.

I am just going to go ahead and explain this before somebody embarass themselves:

Light does not travel slower through water, glass or any other fabric. What happens when a photon travels through e.g. water is that the photon will excite an electron/atom/ion/molecule, and then the electron/atom/ion/molecule will deexcite and send out a new photon with the excact same energy as the original photon had.

In retard terms: Photon hits water, water eats photon, water spits out new photon, this process repeats itself until the photon (which isn't the original photon, more like the grandgrandgrandgrandgrand^90000000 child of the original photon) comes out on the other side.

>>2670228
>>those who say light has no mass, what rules out the possibility of the photon (assuming you believe in photons) having a miniscule amount of mass that is negligible for nearly all calculations?

I have another question to add to this:

Those who say that light has no mass, what rules out the possibility of photons existing in exactly 239 dimensions, and photons having mass in dimension #177?

>>2670540
and of course, this takes more time than it would take a photon to travel the same distance as if it were traveling through a vacuum, which is why it is said that light "slows down" when in fact it is simply doing what friend-anon has just explained

the photon travels through the space between each molecule at c, but takes time for it to do the little excitement bit, more than it would to travel the width of an atom in a vacuum

Photons, How Do They Work???

>>2670228

Nothing experimentally. Theoretically, it does not couple with the Higgs boson.

>>2670540

Wise anon is wise.

>>2670547

You don´t seem to understand the concept of mass.
Mass is a scalar quantity.

>>2670885
it's not really wisdom so much as it is knowledge

On photon masses.
a) Photon may be seen as having mass in some crappy theories nobody uses but highschool textbooks. Their predictive powers are about as good as taking an educated guess.
b) In special relativity, mass is a scalar. It does not depend on the coordinate frame chosen, so boosting (i.e. choosing a moving coordinate frame) doesn't change mass.
c) The same thing applies to general relativity.
d) Quantum field theory requires the photon to be massless, otherwise it would have finite range (and violate some other stuff). Mass is what keeps W and Z bosons from flying around. Experimentally, there's an upper boundary to the photon mass that is pretty small, I think it was around <span class="math">10^{-18}~MeV[/spoiler] (divide by <span class="math">c^2[/spoiler] to get the SI value).

>>2670943

Exactly! Now i can sleep well tonight.

The short answer is "no", but it is a qualified "no" because there are odd ways of interpreting the question which could justify the answer "yes"