A question about a hypothetical time travel device utilizing rotation

I know many of you have seen rotating space stations in science fiction movies and television programs. This is used to simulate gravity in most cases. Many know that the speed of a rotating object increases as you move outward from the axis. Lets say that at some point the radius is great enough (and then some) to reach the speed of light. What happens here? Should I brush up on the Ehrenfest Paradox even though it assumes there is absolute rigidity ? Would time come to a stand still?

What would happen if you made the devices radius even longer, so that it could theoretically go faster than the speed of light?

a reply to: SharonGlass

Let's say a person could withstand the serious pressures at that type of speed.

Let's also say there was the technology to get to those speeds without ripping the ship apart.

You still have a problem with speed being relative. The closer you got to the speed of light, someone observing you wouldn't see you going that fast. Also, you wouldn't see the person watching you going by that fast. In essence you would actually slow down rather than speed up.

a reply to: TerryDon79

Let's say a person could withstand the serious pressures at that type of speed.

Let's also say there was the technology to get to those speeds without ripping the ship apart.

I assumed that if it was a gradual acceleration up to and past the speed of light, there would be reasonably comfortable pressures for both man and device?

I know time and speed are relative, and that time stops at light speed (theoretically?) but what happens when you break that barrier? Is Einsteins' relativity wrong in that nothing can go faster than light? Or what?

Thanks for sharing your though experiment with me.

Mass also increases with velocity. This prevents acceleration to the speed of light. It would require increasing amounts of energy, to the point of an effective infinite level.

What if inside the station lies a fan of whatever that turns counterclockwise, while the rest rotates clockwise?

originally posted by: SharonGlass
a reply to: TerryDon79

Let's say a person could withstand the serious pressures at that type of speed.

Let's also say there was the technology to get to those speeds without ripping the ship apart.

I assumed that if it was a gradual acceleration up to and past the speed of light, there would be reasonably comfortable pressures for both man and device?

I know time and speed are relative, and that time stops at light speed (theoretically?) but what happens when you break that barrier? Is Einsteins' relativity wrong in that nothing can go faster than light? Or what?

Thanks for sharing your though experiment with me.

The stresses and pressures I won't go into as such a device isn't known (yet) so it would be pure speculation on my part.

Let's try looking at it this way.

You have a person (A) on a string accelerating towards the speed of light. Another person (B) standing watching the other person.

As A approaches the speed of light B would see them at, say, 99% the speed of light. A would also see B at 99% the speed of light.

Now, when A goes faster, B would appear to slow down to keep the observable speed below 100%. B would also see A slowing down to keep the speed below 100%.

Plus, the faster you go, the higher your mass would be. To the point of needing infinite propulsion for infinite mass.

ETA If I'm wrong can someone point it out? I don't mind being wrong

a reply to: SharonGlass
.
Time travel? yes. Faster than light travel? maybe not.

It would take a fundamental change in our understanding of the universe to exceed the speed of light. As for time travel that is possible-but only fowards in time. Astronauts are a trillionth of a second younger then the folk at Houston.

Time is an illusion created by man-all there is is motion. Time is simply motion and distance despite those who argue that time is a fourth dimension.

a reply to: SharonGlass

Tipler cylinder

originally posted by: SharonGlass
What happens here? Should I brush up on the Ehrenfest Paradox even though it assumes there is absolute rigidity ?

Your own source says what would happen, that the disc would fly apart when transverse velocity exceeds about the speed of sound in the disc material. Even assuming a non-existent material with no such limitations, the below posters are right in agreeing with Einstein that achieving a transverse velocity of light would require infinite energy, even if they disagree with Einstein on a minor interpretation point. Applying an infinite amount of energy is equally impossible as making the disc out of a non-existent material. So how far you can go in the thought experiment depends on how much reality you want to discard. If you keep discarding more and more reality I suppose you can keep going but I'm not sure how that's useful.

originally posted by: Phage
Mass also increases with velocity.

Not according to Einstein, but Richard Feynman was a respected physicist who popularized that idea even though Einstein said it's not mass that increases with velocity, but momentum. I think Einstein would say Feynman mis-applied the E=mc² equation as that's not really the correct equation for objects with momentum.

This prevents acceleration to the speed of light. It would require increasing amounts of energy, to the point of an effective infinite level.

The rest of this is still true either way, since it requires increasing amounts of energy to give the object increasing amounts of energy.

originally posted by: TerryDon79
Plus, the faster you go, the higher your mass would be.

Again, not according to Einstein, but according to people who apparently mis-applied a simpler equation, instead of using the full equation with momentum term, as explained in the linked thread.

a reply to: Arbitrageur

So mass doesn't increase with speed? I thought that was a commonly accepted thing? I'll have to look into that later so I get my facts straight.

Damn you making me do research

a reply to: Arbitrageur

Just had a quick read of the thread you linked to and another one.

One question. Is it actually energy that increases and not mass?

(Sorry for being off topic OP)

originally posted by: TerryDon79
a reply to: Arbitrageur

So mass doesn't increase with speed? I thought that was a commonly accepted thing? I'll have to look into that later so I get my facts straight.

Damn you making me do research

That depends on whether you believe Albert Einstein or Richard Feynman. While I have great respect for Richard Feynman's work, I have even more respect for Einstein's ideas on relativity, so I would tend to agree with Einstein on this point.

originally posted by: TerryDon79
One question. Is it actually energy that increases and not mass?

The correct equation roughly says in English that the total energy of an object is a function of its mass and a function of its momentum, added together. The mass doesn't increase with velocity, but the momentum does.

Another thing to note is that a photon has energy, but no mass so the mass term is zero, so it gets all of its energy from the momentum term. This is another strike against trying to use E=mc² to determine the energy of an object, as Richard Feynman apparently tried to do.

a reply to: Arbitrageur

So with the "getting to light speed" topic.

Momentum increases (mass and velocity) so that would increase the energy as energy equals momentum plus mass.

a reply to: SharonGlass

Superman did it.....

a reply to: SharonGlass

Tipler did the math for this in the 1950's....link

Current technology could reduce the size to a singularity, a single point in space, with sub-atomic sized black holes as the dynamo (being created in the LHC as we know).

Just like to add, that one thing to consider about time travel is the movement of the earth and solar system.

Travel through time and now the solar system has moved somewhere else. Even if the solar system didn't move, the earth still does.

So after you time travelled, now you need to find the sun and earth, and travel there

What was is no longer there, so you can't go back to it.
Reverse time travel is a cosmological constraint that can't happen.

Regardless of whatever velocity you obtain in any direction, how would that undo all that is & was.

K~

originally posted by: aethertek
What was is no longer there, so you can't go back to it.
Reverse time travel is a cosmological constraint that can't happen.

Regardless of whatever velocity you obtain in any direction, how would that undo all that is & was.

K~

It sounds funny to have to say this, but I believe velocity can't undo all that was on a time line. I also think that a new timeline would then exist to accommodate the new direction from the old one should time travel exist as we suspect.

a reply to: Justoneman

OFFS, That "Time Line"? that you speak of is every creation,orbit, decay & destruction of every speck of everything that would need be undone to go "back in time".

Why is this such a hard concept for people to grasp?

How would any "machine" that you could manufacture undo every physical event in time & space of matter & energy that has already happened & no longer exists.

K~

a reply to: Arbitrageur

I'm sure that Feynman would have said that E = gamma(v) * m0 * c^2, with gamma(v) tending to infinity as v->c .

And then you could lump gamma(v)*m0 as the effective 'relativistic mass' or something, but it's true that the now standard way to explain things is that the Newtonian relationship between mass and momentum is not true relativisically, and mass always means rest mass and the thing which is equivalent to inertial and gravitational mass.