Is infinite linear acceleration possible?

Question

I was thinking about the relativistic example of the scientist in a box. He feels an acceleration equal to the force of gravity, and is unable to determine if he is at rest on earth, or accelerating at 32 ft/sec squared through space (assume there are no windows in his box). Wouldn't a simple wrist-watch be a device that would answer this for him? I'm assuming that if you accelerated long enough, you would eventually reach the speed of light. So if you waited long enough with no apparent change in your acceleration, you might prove that you are at rest on Earth. Unless you could accelerate in one direction (i.e. not in an orbit) forever and somehow never reach the speed of light (is that theoretically possible?). Also, if gravitons are ever discovered, how would that change the scenario? Could you determine the presence of a large gravitational body like the Earth, or would acceleration itself produce gravitons?

If the scientist were in a box at the end of a rope being spun around, I believe he could use a gyro in the box to detect his motion. As he completes a revolution in the box, his gyro should make one rotation. However, I agree that he would feel a similar (if not identical) acceleration.

Answer 1

I agree with #1. The theory of relativity does not allow anything in this universe with MASS to reach light speed, ever. Even with an inverse Tau, you would simply bypass the speed of light.

THE PROBLEM IS: The theory of relativity PROHIBITS ANYTHING with MASS from reaching the speed of light or the theory of relativity itself BREAKS DOWN! kAPUt!

Answer 2

A lot of people have been saying No.. Not possible.. I think that is a very bold statement. Their main arguments seem to be about einsteins relativistic mass equation. The thing is, light travels at the speed of light. Therefore speeds at the speed of light are possible. This is a fact. However, in order to achieve infinite constant acceleration we'd have to, at some time, surpass the speed of light.
If we accept there are particles slower and the same speeds as light, then it is fair to assume that faster than the speed of light is eminiently possible.
But does this answer your question?
NO.. Because the question is not dependent upon speed.. The most limiting factor is time.. You are looking for infinite... Since the universe is not infinately old, and assuming it doesn't last forever then universe linear accelleration cannot exist.
Still on the subject of the universe and gravity; we know that the mass of the universe is basically fixed. We understand the universe started off with the big bang and the "centre" of mass of the universe is somewhere out there but exists.
That means that gravity is going to bend everything, even light into a massive circular motion within the limits of our universe..
Similarly.. the definition of a line in mathematics is "a section of a curve of infinite diameter." This is found through numerical anomilies in geometry.
Therefore there is no such thing as a straight line in the way you are meaning and therefore, there can be no such thing as accelleration in a straight line. It has nothing to do with mass.
Gravitons are probably only going to be "particles" like photons which are handy for explaining gravity.
Going back to enstein.. If accelleration produces a relativistic mass increase then, accordingly there should be a relativistic increase in mass, which means "more gravity"... But don't forget.. this is all relativistic to us here at the speed we're at.
It's not a fundamental. So a relativistic mass increase may not neccessarly increase "gravitons", but again.. may not neccessarily increase mass.
Relativistic is a word which is handy to use when our empirical picture of the world doesn't work very well.. Remember, Photons are not infinitely massive!!!

Answer 3

Considering all of the relevant relativistic effects (time dilation, Lorentz contraction, mass increase, principle of equivalence), your scientist couldn't tell. You would never reach the speed of light, but your measurements would show you were continuously accelerating at 1G.

Here's another indistinguishable scenario: your scientist's box is at the end of a very long rope spinning fast enough to experience a 1G acceleration toward the other end of the rope.

Gravitons are virtual particles, mathematical constructs. As mediators of the gravitational force, they wouldn't be present in the acceleration-only scenarios. They would be unaffected by the presence of an additional gravitational mass, they would be undetectable, and they would be irrelevant to the principle of equivalence.

If someone discovered a real particle relevant to gravity and it was detectable and usable to distinguish between gravity and acceleration, they would need to call it something other than a graviton, because it would be entirely different.

Update: Billy is correct, the gyroscope would tell him of his circular path and its transit time. If he knew the radius, he could calculate the acceleration and compare it to his measurements.

Let's say Dr. Speed has been in his box asleep for an unknown amount of time, all his instruments turned off. He has no idea of his speed. He measures the acceleration of G but has no idea how long it has been that way. The driver of his space tractor has also been asleep. He fires up the tractor but also has no idea of his speed. Since there is no absolute reference for speed, all of their measurements would be identical, whether their speed compared to their starting point was 0.9c or -0.9c or anything in between. By the time they are ready to break the speed limit, it's time for another nap. This could go on forever.

In the frame of reference of the tractor driver, he just sets his throttle at 9.8 and the thrust from his engine is enough to produce the required acceleration. In the frame of reference of the starting point, the same force is applied to an ever-increasing relativistic mass, producing an ever-decreasing acceleration.

Answer 4

1. The watch will not answer anything because it experiences the same as the person. The two are at rest relative to each other, so neither will know what they feel is.

2. If you could keep the acceleartion constant, you can reach the speed of light. But as you accelerate, the mass increases, and the force required to maintain the acceleration increases, and it goes to infinity as you go close to the speed of light,

Answer 5

At 1g it would take a heck of a long time to reach the speed of light, and then there's the relativity effects, from his perspective he would keep on accelerating though an external observer would say he was approaching the speed of light. He'd be suffering time dilation effects that would let him think he was still accelerating.

Then again, what's the point of debating the practicality of a theoretical situation? The instantaneous inability to discriminate between gravity and acceleration is the important thing, not the ultiimate inability.

Answer 6

no sorry
you must remember eisteins theory of relativity.
E=mc2 which means that the faster something travels the more energy (E) it uses and the heavier (m) it gets up to the speed of light (c) so you cant go the speed of light or faster.

Answer 7

in reality no because of friction