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Reflected starlight would be blue shifted into the UV.THX1138 wrote:
( 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 ,
THX1138 wrote:
Then also the same question with object moving at above C velocities. Would either even be visible to us?
http://en.wikipedia.org/wiki/Cherenkov_radiation wrote:
<<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,.>>
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.THX1138 wrote:( 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
Markus Schwarz wrote:
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.
http://en.wikipedia.org/wiki/Brandenburg_gate#Berlin_Wall_and_its_fall wrote:
<<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.>>
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 wrote: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!
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 wrote:Chris, did you include the meatballs in your calculations :?:
Chris Peterson wrote: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 wrote:Chris, did you include the meatballs in your calculations
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. 
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 wrote: :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:
Well, at least i wouldn't freeze from the wind chill 
Neither would anybody else for miles around.Beyond wrote:Nuclear Fusion :?: :?: Well, at least i wouldn't freeze from the wind chill :!: :lol2:
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.THX1138 wrote: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.THX1138 wrote: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.
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.Nitpicker wrote: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.
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.Markus Schwarz wrote: 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.
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).Nitpicker wrote:All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.
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 wrote: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.
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).Chris Peterson wrote: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).Nitpicker wrote:All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.
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.
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.Chris Peterson wrote: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 wrote: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.
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 wrote:Thanks Chris. I didn't know there were any known massive objects moving apart that fast with respect to another.
Oh, well, I hadn't considered further than the observable universe. I feel quite the Pfuel.Chris Peterson wrote: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 wrote:Thanks Chris. I didn't know there were any known massive objects moving apart that fast with respect to another.
