Speed of light

I get that photons have no mass according to Einstein's special theory of relativity, but why do they get pulled by gravity?
i.e. black holes?

>How can we know
What do you mean by "we", Peasant?

Gravity doesn't pull. It bends spacetime. Light travels in a straight line through bent spacetime. That makes it appear to curve.

>why do they get pulled
They don't. Gravity only changes the path of light. Below the even horizon of a black hole, for instance, all possible paths simply point inward.

Because the space-time itself is warped by mass. The straightest possible line around a mass such as a star or planet is a hyperbola. Additionally light emitted from a large mass will be red-shifted as it escapes the gravity well due to conversation of energy.

We already know light isn't the fastest. Quantum entangled action at a distance is faster. Maybe infinitely fast.

Got it, thanks.

I mean, you, scientists.

I doubt there is movement through space involved, so no "speed".

Because Maxwell's equations apply in all inertial frames of reference.

This desu
The exact speed of light is derived from electromagnetism, but because of that fact it has to be constant in all frames of reference. People familiar with galilean relativity before Einstein were pretty confused by this.

>How can we know that the speed of light is the fastest?
What about the separation of the light itself? Think about two sources of light in spacetime, both pointing opposite of each other. The light any one source is moving away from the other at twice the speed of light because of relativity. You can visualize this in a spacetime diagram, in a lattice clock, and using frames of reference.

This is probably wrong...
The speed of light can be squared making it accelerate faster due to an expanding force like the explosion of a massive body in space pushing the light at it's own speed due to the expansion of the blast. So... c m/s^2

Is there any good book on electromagnetism that includes Maxwell's equations for absolute retards?

e=mc^2 is only the amount of energy present in mass. Velocity vectors are not able to be added like in Newtonian physics when you are travelling at relativistic speed (where the error starts causing issues). The equation to do this actually gives you an answer of exactly the speed of light in the opposite direction of travel (quit easily simplifying down to -2c/2).
You take the second equation in picture related. The resting observer can be any frame of reference, as both particles are at the speed of light.
>u=-c
>v=c

Will the universe ever expand at a rate faster than the speed of light

It is. Look it up. We observe stars that are expanding away above lightspeed all the time

>Cause and effect would not work if we found something that could travel faster than light.
>People saying this shit
Nothing actually indicates this would be the case. You could never receive a reply to a message you hadn't sent yet. Just because the receiver is a billion light years away and suddenly moves 500 million light years closer won't change when you sent the message only reduce their distance to the causal factor. If that distance happens to be zero, they still won't receive the message before you send it even if you send it faster than light can go.

Quantum 'entangled' particles are actually just the same particle trapped in a particle sized wormhole. That's why measuring it appears to affect both particles at the same time, since it is really just one particle appearing in two places.

what if there's things going faster then light but we don't know because we can't see them because there's no light shining on them because they're faster then light

v. smart

...

Any second semester Physics textbook

almonds: activated

According to Wikipedia (IFL starting posts on Veeky Forums with that) the universe was expanding faster than the speed of light in its first few whatever-seconds.

kekaroooo

>How can we know that the speed of light is the fastest?

By using maths that apparently are beyond you.

So is Photonic the Hedgehog faster than Sonic?

>We observe stars that are expanding away above lightspeed all the time

How would we observe them? How does light get to us from something moving away faster than light?

Because the light is still going at the speed of light, even if the thing, relative to us, is moving faster than light.

it aint, muh dick is faster when i thrust it in your wifes vagina.

We observe billion year old light emitted in the distant past when they weren't moving away too fast.

en.wikipedia.org/wiki/Group_velocity#Superluminal_group_velocities

Just think about people doing "the wave" at sporting arenas. They just stand up then sit back down in a synchronized fashion. If everyone is properly synchronized, there is no limit to how fast the wave can move.

I read this in rick Sanchez''s voice xD

You could use this to create a gravitational "sonic boom"

I don't want to say bullshits, but what about dark matter? Could it not interact electromagnetically with matters since it moves too fast for light to reach it? Or dark matter doesn't exist and it's only a simplification for phenomena we can't explain without a new set of laws that don't respect special relativity?

>How does light get to us

youtu.be/6CUe5SkMSIo?t=3m

>meme matter

The theories don't require causality, it is only imposed on them for us to be able to make sense of the predictions. GR or QM would work just as well without causality.

How far apart can two quantum entangled particles go?

It's not really a matter of being far apart, it's just a matter of space being connected in a non-intuitively-contiguous manner. What's not really understood is how the space gets connected in the first place. If we knew that, we'd be able to 'entangle' things more reliably and likely the method would also determine the limit on how far apart they can be.

Well, thats not entirely true. A photon has relativistic mass because a photon has energy E = hf where h is Planck's constant and f is the frequency of the photon. Energy is equivalent to mass according to Einstein's formula E = mc2. A photon has momentum, and momentum p is related to mass m by p = mv. This relativistic mass is a measure of the energy E of a particle, which changes with velocity. By convention, relativistic mass is not usually called the mass of a particle in contemporary physics, but you can say that the photon still has relativistic mass.

No such thing as a photon. Guy who coined the word was trying to make telekinetic helmets to talk to his cats.

They are, as space itself is expanding.

Does nobody read Moshe Carmelli? Nobody at all?

Ok so basically as soon as we figure this out we can essentially have delay less information transfer through quantum entanglement

delay less, but slow. since you can only transfer serial data with that one entangled qbit. building a machine that can entangle like 1qbyte would be nuts. that one entangled bit already takes up a whole lab of equipment to achive what anton zeilinger did in austria, when he and his team entangled a photon across the river danube, and measured the instant changes on the other side when they manipulated the entangled photon. in 99 they did a dual qbit entanglement i think

Well you could travel through a medium outside of space and time.

>some science guys makes the first ftl radio
>they turn it on for the first time
>ayy lmao chatter with the volume turned up to 11

Does it really count as winning a race if the start line and finish line are the same thing at the same time?

Relativity was invented primarily because of the observation that light appears to be moving at the same speed no matter how fast you're moving towards or away from the source of the light.

The rest of it is just math. Math which at least APPEARS to be in line with the way the world behaves.

Yeah, relativistic mass is a useful enough concept when starting off, but you'll have to unlearn it soon enough
Relativistic momentum will serve you better if you're sticking with learning SR to an undergrad level at least
Special relativity by French is the go to SR undergrad textbook where I'm from, and at a higher level, General Relativity for Mathematicians/Graduate texts in mathematics is good for higher levels stuff
Apologies for typos, I'm a bit drunk atm

What if you move the universe instead???

But what if two people were moving the universe at the same time?

Tell them to get their own universe!!! Or atleast only move the universe between them and their destination.

...

Huh...?

Sorry, cant do that.

>still perceiving things in terms of light
Only when we move beyond this will we solve dark matter and energy

>How can we know that the speed of light is the fastest?
I have a serious question:

Imagine I am floating in space holding a stick 1 light year long in length, made out of some fictionally strong material.

imagine at the other end of this stick is an observer.

If i grab the stick and start waving it from left to right, does the observer on the other end of the stick receive this information instantaneously? Or does the observer need to wait for over a year to see the stick move on his end?

No, the transfer of energy between atoms isnt instant. You will get a noodle poll that tkea one year for the end to jiggle

The space isexpanding.They don't travel through space ftl.

huh.

so it is impossible to have a material stiff enough to act in this manner?

So is there some way to determine how fast information can travel in this fashion? I am assuming it has to do with the strength of the molecular bonds in the material.

I guess if you view this long stick as just a chain of little magnets, not actually physically secured to each other, it makes sense that it would noodle over long distances

Why, because they have the word "dark" in them? Retard.

>So is there some way to determine how fast information can travel in this fashion?
It's determined by the speed of sound through the medium, IIRC.

Also worth noting, the transfer of energy between atoms isnt 100% effecient

This problem is multidimensional... getting down to the frequency...
It is rely hard to explain and to understand this you need to know quantum part of physics, and some electromagnetic field interaction to...
simply light didn't travel with the same speed always. speed we know as light speed is a distance traveled in certain time in total vacuum . In deferment material it travels with different speed, that's why you have refraction, the same effect you can find in other radiations as f.g x-ray's.
We know light is refracted by mass as well, and Thats because light has a mass itself.
if we take multidimensional view on light ray we can find in some dimensions travel projected on other can be faster than light speed in 3d...
but i will not elaborate on this topic... not enough letters on Veeky Forums :)

After doing some research, I found someone somewhere on the internet that said this:

>except in neutron stars the speed of sound seems to be limited to the speed of light divided by the square root of 3, that is, v < 0.577 c

>2physics.com/2015/01/sound-velocity-bound-and-neutron-stars.html

review your space time diagrams.

The maximum speed is not governed by light. It's just a coincidence that light happens to travel at the maximum speed of the universe, which is the speed of causality.

Saying you want to go faster than the speed of causality is saying you want to affect events before they happen, which is logically inconsistent and nonsensical.

Then what if we just make light faster?

No, entanglement can't send information. After all, how could it? measuring something in quantum physics is the same as in non-quantum physics -- it is just the process of updating your information about a particular variable.