Warp - any scientific take on it?

[Kuciwalker]

Actually I'm surprised KH didn't correct me on a couple mistakes I made in my earlier explanations - specifically, that no amount of acceleration will actually move Event A from B's past to its future, and that B has to be outside A's light cone.

[Kuciwalker]

edit: wtf is the forum so slow

[Kuciwalker]

Actually I'm surprised KH didn't correct me on a couple mistakes I made in my earlier explanations - specifically, that no amount of acceleration will actually move Event A from B's past to its future, and that B has to be outside A's light cone.

[KrazyHorse]

Originally posted by Kuciwalker
Actually I'm surprised KH didn't correct me on a couple mistakes I made in my earlier explanations - specifically, that no amount of acceleration will actually move Event A from B's past to its future, and that B has to be outside A's light cone.

I actually didn't bother reading it fully.

[korn469]

What happens when two objects collide into each other if they are both traveling at 95% of C? Would the force of their collision happen at the speed at light, at 95% of the speed of light or at 190% of the speed of light?

[KrazyHorse]

Originally posted by korn469
What happens when two objects collide into each other if they are both traveling at 95% of C? Would the force of their collision happen at the speed at light, at 95% of the speed of light or at 190% of the speed of light?

You're basically asking what the relativistic addition of velocities is.

If, in the lab frame you have one body approaching from the left at u1 and one body approaching from the right at u2 then the formula (which is easily derived via the Lorentz transforms) is that an observer on either body sees the other approaching at:

(u1+u2)/(1+u1u2/c^2)

Which, it is easily demonstrable, can never exceed c for u1 and u2 less than c

[KrazyHorse]

For 0.95c the relative velocity of one wrt the other is 1.9/(1+0.95^2) = 99.87c

[TCO]

But my point is that the equations don't. e=mcsq has no "information term".

Let's say I have two dudes that are stationary. And I have a quantum thingie device that allows them to transmit info instantly (or faster than light). Now it only works between those two end points. And the endpoints are not moving wrt each other. Well, then how the heck does sending a message, mean that I can send messages back to myself in time? It doesn't.

Now, if there are other reasons why the quantum thingie can't exist fine. But not because of sending messages to myself back in time. Because, that device doesn't do that.

[self biased]

just like if you shine light through a diamond, it's less than C... bollocks. i have to leave for work. i'll add to this later.

[TCO]

Originally posted by KrazyHorse
For 0.95c the relative velocity of one wrt the other is 1.9/(1+0.95^2) = 99.87c

Assume the collision is inelastic and the bodies are same size and hit dead on. And all the KE (but none of the rest mass) is converted to heat. What's that going to be?

[KrazyHorse]

Originally posted by TCO
But my point is that the equations don't. e=mcsq has no "information term"

The point is that there is a more fundamental objection to FTL transfer of info than simple E=mc^2

[KrazyHorse]

Originally posted by TCO


Assume the collision is inelastic and the bodies are same size and hit dead on. And all the KE (but none of the rest mass) is converted to heat. What's that going to be?

Then you have to go to CM frame. That is the frame in which all KE will be converted to heat.

If both bodies have same mass and velocity in lab frame (equal and opposite) then the lab frame is CM frame and the amount converted to KE will be 2*(gamma-1)mc^2 with gamma measured in lab (i.e. CM frame).

[TCO]

Mebbe so. But I don't get how the exact situation that I described allows info transfer to myself back in time.

[KrazyHorse]

Well, then how the heck does sending a message, mean that I can send messages back to myself in time? It doesn't.

That is correct. Without a boost at some point it doesn't work. But when you start to do boosts in the middle you end up ****ing up causality.

[KrazyHorse]

If everybody's at rest then of course relativity doesn't do anything. Relativity is only meaningful when you have to jump from one frame to another.