Science is interesting

[YCobb]

It's because they measuring your speed based on your initial velocity, right?

also there's a bunch of weird time shit in there

[Brekkjern]

Too bad I am trying to get into the gaming industry... There I could just make up a reason like dimension jumps, mass effect, warp, fart power or whatever.

Anyone care to explain without using "because Einstein said so"?

[D-vid]

Well, the 1,5 times c would only be from your perspective as a stationary object inside a moving object, perceiving another moving object. The objects themselves still only move at their own speed.

[Kamak]

Anyone care to explain without using "because Einstein said so"?

Really it's one of the few answers that doesn't get overly technical, so you're likely to not get an answer besides "because E=mc2!" (assume that 2 is an exponent)

I'm still trying to get an answer from a couple of physics professors on why light is believed to be massless even though it's a wave and a particle (which would mean it would have to take up SOME space, no matter how minuscule).

[Exeres]

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

Every time I try to read it, my eyes cross and refuse to straighten themselves out, so you can take a crack at it.

[Brekkjern]

Read through it. Makes sense the way it is written there, but that is not the way it has been explained to me at all.

The article says that you cannot move faster than 1 c relative to space. That is the important part. I have been told that objects can't travel faster than 1 c relative to each other which is now obviously false.

[Kamak]

Read through it. Makes sense the way it is written there, but that is not the way it has been explained to me at all.

The article says that you cannot move faster than 1 c relative to space. That is the important part. I have been told that objects can't travel faster than 1 c relative to each other which is now obviously false.

The only time the relative to eachother problem comes up is in the theoretical "if you're driving at the speed of light, and you turned your headlights on, you won't see the light until you slow down" story. The light doesn't go faster just because you're going faster (it's not cumulative). It just travels the same speed as you.

[Brekkjern]

Yeah, I understand that now as it is relative to space and not the objects in space. My teachers (who aren't professors or anything) never said relative to space. They just gave the "because Einstein said so" reason.

[Madican]

Also isn't there the whole relativity bit? As in the closer you get to light speed, to an outside observer you appear to be going infinitely slow?

[Syobon]

In short, you can't go faster than light because the faster you go, the slower time passes for you. When you try to reach the speed of light, for example when you try to catch up to a ray of light, when you accelerate time slows down and you won't be able to reach it.

The time dilatation is such that no matter how fast you go, the speed of light relative to you is always c. If you're standing still and see light moving at c relative to you, and you accelerate to 0.5c, time will slow down and the light will still be moving at c relative to you.

I made a slightly more comprehensive post about this effect and how it can be used to travel to the future a few pages back.

Don't worry if this doesn't make sense to you, it's not supposed to.

[Ersatz]

What Syobon said.

Theoretically, you can go faster than light (like the particles Kamak mentionned: if the current theories are right, those particles would travel back in time and would gain velocity by losing energy.) But you can't travel to the speed of light because that's mathematically impossible. I don't know the whole equation, but it is something divided by √(c-v), which means that if v=c, you divide by zero, which is impossible. The equation would still work with v>c if you consider imaginary numbers.

(I'm only repeating what I have read and discussed with a friend who had that class last year. I'll only have it next semester so I hope I'm not saying anything wrong.)

Don't worry if this doesn't make sense to you, it's not supposed to.

That reminds me of my organic chemistry teacher. She quoted Schrödinger some weeks ago: "If someone understands quantum mechanics, he doesn't understand it".

[Syobon]

I don't know the whole equation, but it is something divided by √(c-v), which means that if v=c, you divide by zero, which is impossible. The equation would still work with v>c if you consider imaginary numbers.

Unless of course the equation is wrong, but it has been proven right by experiments I think, so it's doubtful that it is.

Note that it's only explained why it's not possible to go faster than light, not how. The full answer to how is still unknown I think. The thing is that the speed of light is currently one of the fundamental laws of the universe, like Newton's second law: F=ma although that's actually wrong since it doesn't take relativity in account..

Why the laws of the universe work the way they do is still being researched, and is part of quantum physics.

[Brekkjern]

The equation might just have validity with sub c values though. I have no idea, but I know the general speed equations and such that we have are only valid at low values.

[Syobon]

I think what you've heard Brekkjern, is that the equations you learned in high school are only valid at low speeds. At very high speeds, ie approaching c, you switch to the relativity equations, which were mentioned earlier.

Note that at extremely low values, the equations become invalid again, and you have to switch to quantum physics.

This is all because your answers only need to be approximately right though, not because the laws of physics suddenly change at high speeds or low values.

tl;dr, the stuff you learned in high school was wrong, but close enough to the truth.

[Syobon]

Science requires no belief, only a logical and open mind.

Also worth noting is that not only time but also size and mass is relative to an object's speed. The faster an object goes, the more mass it has, and the smaller it appears to an inert outside observer.

Further, none of this is purely theoretical, it has all been proven by experiments.