Moving close to and above C

[THX1138]

( Traveling towards us ) What would an object with mass look like when viewed from earth if it were moving towards us at just under C , Then also the same question with object moving at above C velocities. Would either even be visible to us?
After all you just never know when some random NCC1701 might happen buy these days

[neufer]

( Traveling towards us ) What would an object with mass look like when viewed from earth if it were moving towards us at just under C ,

Reflected starlight would be blue shifted into the UV.

Emitted IR might be blue shifted to the visible.

Then also the same question with object moving at above C velocities. Would either even be visible to us?

[b][color=#0000FF]The geometry of the Cherenkov radiation (shown for the ideal case of no dispersion)[/color][/b]

---

• No (as regards object moving at above C velocities).
  
  (You don't hear supersonic jet planes
  until they have passed you by.)

<<Cherenkov radiation, also known as Vavilov-Cherenkov radiation, (also spelled Čerenkov) is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. The charged particles polarize the molecules of that medium, which then turn back rapidly to their ground state, emitting radiation in the process. The characteristic blue glow of nuclear reactors is due to Cherenkov radiation. It is named after Russian scientist Pavel Alekseyevich Cherenkov, the 1958 Nobel Prize winner who was the first to detect it experimentally. A theory of this effect was later developed within the framework of Einstein's special relativity theory by Igor Tamm and Ilya Frank, who also shared the Nobel Prize. Cherenkov radiation has been theoretically predicted by the English polymath Oliver Heaviside in papers published in 1888–1889,.>>

[Markus Schwarz]

( Traveling towards us ) What would an object with mass look like when viewed from earth if it were moving towards us at just under C

Here is a simulated flight through the Brandenburg gate. One is with 0.9c the other with 0.99c. In the latter video, towards the end, you can actually see the back side of the Brandenburg gate (in blue) even though you pass straight through it. To me, this is one of the most stunning effects that happen when an object travels close to c.

[neufer]

Here is a simulated flight through the Brandenburg gate. One is with 0.9c the other with 0.99c. In the latter video, towards the end, you can actually see the back side of the Brandenburg gate (in blue) even though you pass straight through it. To me, this is one of the most stunning effects that happen when an object travels close to c.

• But only a Pfuel would pass through the Brandenburg Gate at 0.99c

<<Only the royal family was allowed to pass through the central archway
[of the Brandenburg Gate] as well as members of the Pfuel family, from 1814 to 1919.>>

[Beyond]

Forsooth, Von Neufer hast once again wielded his mighty Google sword at .999c and delivered to us valuable information to help keep us from making a Pfuel's fool of ourselves, should one or more of us decide to dash through the Brandenburg Gate at close to the speed of C. Hoorah! Hoorah!

[Chris Peterson]

Forsooth, Von Neufer hast once again wielded his mighty Google sword at .999c and delivered to us valuable information to help keep us from making a Pfuel's fool of ourselves, should one or more of us decide to dash through the Brandenburg Gate at close to the speed of C. Hoorah! Hoorah!

Were you inclined to make that dash (at 0.99c), you'd require an energy expenditure of 4.3 x 10¹⁹ joules, the equivalent of a 10,277 megaton explosion. Or in more human terms, you'd need to consume the number calories in 6 x 10¹² kg of spaghetti- the mass of a medium mountain. Better get to eating.

[Beyond]

Chris, did you include the meatballs in your calculations

[Chris Peterson]

Chris, did you include the meatballs in your calculations :?:

Nope. Not the sauce either. I think for getting the most accessible energy as quickly as possible, you should just go for the carbs. It's going to take long enough as it is to eat 6 trillion kilograms of noodles!

[Beyond]

Chris, did you include the meatballs in your calculations

Nope. Not the sauce either. I think for getting the most accessible energy as quickly as possible, you should just go for the carbs. It's going to take long enough as it is to eat 6 trillion kilograms of noodles!

Dats an oodle of noodles I like spaghetti, but that noodle is just a bit toooo long for me to suck up I'll let someone else zip through the gate.

[Chris Peterson]

:shock: Dats an oodle of noodles :!: I like spaghetti, but that noodle is just a bit toooo long for me to suck up :!: I'll let someone else zip through the gate. :mrgreen:

Good idea. Especially since getting up to that speed from anywhere on Earth would raise the temperature of the muscles in your legs high enough that the atoms would undergo nuclear fusion. Ouch.

[Beyond]

Nuclear Fusion Well, at least i wouldn't freeze from the wind chill

[Chris Peterson]

Nuclear Fusion :?: :?: Well, at least i wouldn't freeze from the wind chill :!: :lol2:

Neither would anybody else for miles around.

[Nitpicker]

All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.

[THX1138]

That whole Brandenburg gate thing ?????? Neufer you stated no the object could not be seen if it were traveling above C. No one is going to rebut this ? Well It doesn't seem right but I’ll take it as fact then.
As for all the rest of the banter on this thread ( which amounts to yet another one of the many reasons I like this website ) Art’s (The Pfuel family) The spaghetti, the meatballs and etc. Thanks to all of you for being ready to go there at any time at the drop of a hat. The Pfule family, lol, I nearly fell out of my chair Art

At any rate I take it that any NCC1701 coming this way would be completely invisible if it were motoring along above C, ok thanks.

[Nitpicker]

Neufer you stated no the object could not be seen if it were traveling above C. No one is going to rebut this ? Well It doesn't seem right but I’ll take it as fact then.

Whether it was approaching or receding above C, I'll simply say that no known object, massive or otherwise, could travel faster than light according to best current theory. The mathematics falls apart. So, no, you wouldn't see it, because it wouldn't exist. And if it did, we wouldn't have the theory to answer the question of what it would look like.

As for the USS Enterprise (NCC 1701), its appearance at warp speeds is at the sole discretion of the owners of Star Trek's moral rights. Perhaps I'm too blasé about warp drive -- I was more impressed with the fact that it operated underwater in the last film. Woof, that's a mighty fine inter-galactic submarine!

[Markus Schwarz]

Neufer you stated no the object could not be seen if it were traveling above C. No one is going to rebut this ? Well It doesn't seem right but I’ll take it as fact then.

If an object travels faster than light, all light it emits cannot catch up with it, so you can only see it after it has passed you and its light reaches you. This completely analogous to the sonic boom, as neufer mentioned.

Whether it was approaching or receding above C, I'll simply say that no known object, massive or otherwise, could travel faster than light according to best current theory. The mathematics falls apart. So, no, you wouldn't see it, because it wouldn't exist. And if it did, we wouldn't have the theory to answer the question of what it would look like.

As for the USS Enterprise (NCC 1701), its appearance at warp speeds is at the sole discretion of the owners of Star Trek's moral rights.

That is not quite true. General relativity does admit warp drive solutions. Loosely speaking, they work by twisting spacetime in such a way that the speed of light inside a warp bubble "gets larger" than our familiar 299,792,458 m/s. In theory, it does not violate any laws of physics, such as causality.

Practically though, you need exotic matter, which has negative energy density, and no such (classical) substance is known to exist. I guess we have to content ourselves with speeds smaller than c when traveling through space.

[Nitpicker]

That is not quite true. General relativity does admit warp drive solutions. Loosely speaking, they work by twisting spacetime in such a way that the speed of light inside a warp bubble "gets larger" than our familiar 299,792,458 m/s.

I stand corrected. But if the speed of light inside a warp bubble "gets larger" then any massive thing within the bubble is supposedly still slower than light.

[Nitpicker]

[unfounded speculation]

Maybe an observer on Earth could detect the boundary of the warp bubble, as the Enterprise approached within it? Perhaps the bubble would mask the things behind it?

[/unfounded speculation]

[Chris Peterson]

All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.

No, I considered that. Done properly, you will have consumed all the energy just as you pass through, so your rest mass should be back to normal (I assumed 80 kg) at that point (of course, the relativistic mass and size increases are still there to cause problems).

The bigger issue, which I did not try to calculate, is that after you've taken on all that energy, you mass far more than 80 kg, and all that extra mass needs to be accelerated, too (the classic rocket problem). Also, I assumed that your body would convert the food to energy with 100% efficiency, which obviously isn't the case.

The problem could, of course, be analyzed in gruesome detail. But even the trivial relativistic energy calculation I did serves to demonstrate why getting close to the speed of light is an extremely difficult problem.

[Chris Peterson]

Whether it was approaching or receding above C, I'll simply say that no known object, massive or otherwise, could travel faster than light according to best current theory.

That's not true. The Universe is full of objects that are moving away from each other faster than c. That poses no problems with theory or mathematics at all. In general, nothing prevents bodies from having relative velocities greater than c. What you can't do is take two bodies and accelerate one past c with respect to the other (as that would require an infinite amount of energy). And if you have two bodies moving at greater than c with respect to each other, you can't transmit any information between them at greater than c.

[Nitpicker]

All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.

No, I considered that. Done properly, you will have consumed all the energy just as you pass through, so your rest mass should be back to normal (I assumed 80 kg) at that point (of course, the relativistic mass and size increases are still there to cause problems).

The bigger issue, which I did not try to calculate, is that after you've taken on all that energy, you mass far more than 80 kg, and all that extra mass needs to be accelerated, too (the classic rocket problem). Also, I assumed that your body would convert the food to energy with 100% efficiency, which obviously isn't the case.

The problem could, of course, be analyzed in gruesome detail. But even the trivial relativistic energy calculation I did serves to demonstrate why getting close to the speed of light is an extremely difficult problem.

I wasn't sure about my increasing mass comment, as you didn't show your derivation. I merely thought it might be funny. Clearly wrong (again).

[Nitpicker]

Whether it was approaching or receding above C, I'll simply say that no known object, massive or otherwise, could travel faster than light according to best current theory.

That's not true. The Universe is full of objects that are moving away from each other faster than c. That poses no problems with theory or mathematics at all. In general, nothing prevents bodies from having relative velocities greater than c. What you can't do is take two bodies and accelerate one past c with respect to the other (as that would require an infinite amount of energy). And if you have two bodies moving at greater than c with respect to each other, you can't transmit any information between them at greater than c.

Thanks Chris. I didn't know there were any known massive objects moving apart that fast with respect to another. I must have been too busy pondering other heavenly bodies when my lecturer mentioned that. No wonder I never did very well in modern physics.

But from what Markus has said, it sounds like a theoretical warp drive/bubble is neat workaround, and would allow two bodies to accelerate past C with respect to each other. Just need the exotic matter with a negative energy density. What could possibly go wrong?

[Chris Peterson]

Thanks Chris. I didn't know there were any known massive objects moving apart that fast with respect to another.

All of the Universe on the other side of the horizon the defines our observable universe is moving away from us at faster than c. That's what makes it unobservable. But those relative velocities are the product of the metric expansion of space, not of Newtonian or relativistic acceleration.

[Nitpicker]

Thanks Chris. I didn't know there were any known massive objects moving apart that fast with respect to another.

All of the Universe on the other side of the horizon the defines our observable universe is moving away from us at faster than c. That's what makes it unobservable. But those relative velocities are the product of the metric expansion of space, not of Newtonian or relativistic acceleration.

Oh, well, I hadn't considered further than the observable universe. I feel quite the Pfuel.

[saturno2]

I doubt very much that an " object" traveling to c and above c