I'm currently traveling forward at time, at the speed of 1 second per second.
sqrt(i) is a complex number. That is to say it has an imaginary and real component: sqrt(i) = 0.5*sqrt(2)+i*0.5*sqrt(2)
Complex valued masses are going past what I know, but as far as I know you need to apply quantum field theory again. It turns out that Re(mass) describes mass as we know it, and Im(mass) describes in what time the particle will decay
[QUOTE=deboutonner;29464973]sqrt(i) is a complex number. That is to say it has an imaginary and real component: sqrt(i) = 0.5*sqrt(2)+i*0.5*sqrt(2)
Complex valued masses are going past what I know, but as far as I know you need to apply quantum field theory again. It turns out that Re(mass) describes mass as we know it, and Im(mass) describes in what time the particle will decay[/QUOTE]
I read the wikipedia article earlier on. I brushed over that stuff.
Then doesn't that mean a tachyon is the physical embodiment of decay time?
[QUOTE=sltungle;29465103]I read the wikipedia article earlier on. I brushed over that stuff.
Then doesn't that mean a tachyon is the physical embodiment of decay time?[/QUOTE]
Tachyons don't have complex masses, they have imaginary masses (in SR). The tools to deal with complex masses are in QFT and string theory.
Using E = m(0)*c*(1-v^2/c^2)^-0.5, you can see that if you have a real mass particle travelling faster than c, then you have an imaginary energy. But this is forbidden because m(v)=m(0)*(1-v^2/c^2)^-0.5, and when you take the limit of v->c, mass approaches infinity. In other words it's impossible to have a real-valued mass travelling faster than c.
If you assume a complex mass, then you still have the problem of a real component of mass. The equations of special relativity simply aren't well-equipped to deal with numbers that have both a real and an imaginary component, let alone just an imaginary component on its own; which is why you need to use more powerful tools like quantum field theory. And this is all assuming the existence of tachyons, which there is no experimental evidence of.
[QUOTE=sltungle;29461502]But then that'd lead me to ask: why is imaginary mass more sensible than imaginary velocity, or distance for that matter? In the end none of them really make any sense whatsoever.[/QUOTE]
This was just a cheap explanation but since we live (according to General Relative) in four dimensional Pseudo-Riemann manifold where the dimension of space is a real quantity, velocity (space per time) also must be a real quantity.
Anyway, I just read up a little more and a deeper explanation may be found in [url=http://en.wikipedia.org/wiki/Noether%27s_theorem]Noether's Theorem[/url] about conservative quantities. Here you get a conservative quantity for [url=http://en.wikipedia.org/wiki/Law_of_conservation_of_energy#Noether.27s_theorem]time-symmetric[/url] system (implying the empirical observation that the laws of physics do not change in time): Energy. The corresponding operators/matrices (when e.g. using Quantum Mechanics, which also approximates "classical physics) used for retrieving this conserved quantity are [url=http://en.wikipedia.org/wiki/Self-adjoint_operator]self-adjoint[/url], which means those operators just can have Eigenvalues (here: Energy) which are real.
Still I'm not studying theoretical physics (experimental physics is more fun) so maybe someone who is more deeply involved in the subject of classical mechanics (Lagrangian, Hamilton-Formalism, Noether etc) can clarify this. I just quickly compiled the things I remembered in a way which made sense to me.
[editline]27th April 2011[/editline]
[QUOTE=Contag;29463104]That's what happens when you decided to physics.
Look at Einstein - he decided to become a physicist, and [B]bam[/B] world war.[/QUOTE]
Remember, as for Einstein and his cousin Larry, history only remembers one of them.
[editline]27th April 2011[/editline]
[QUOTE=deboutonner;29463771]In terms of special relativity, you make one assumption: that causality is preserved. The fact that imaginary mass leads to a velocity greater than c violates this assumption. You can disregard it.
It actually takes an understanding of quantum field theory in order to make tachyons causally preserving. Basically there is a way to show that tachyons cannot transmit information faster than light and this is enough to show that backwards time travel is not possible.[/QUOTE]
I sadly never applied to Theoretical Physics IV which was about QFT. May you specify this a bit more, I'm quite interested in the outcome for this regarding QFT.
Long live space rays
I just wanted to say that aVoN has rated me Winner and I am happy. I am still sick and doped up on cough medicine, but happy.
If you spend a year traveling in time, you technially are still getting old therefore, as you get back to the regular time let's say a minute after you started, you will be on year older than before.
There are things I don't really understand about astrophysics;
Does light really always travel at the same speed, no matter the repository ?
That doesn't make sense.
Also, if it isn't possible to travel at the speed of light, how is it possible for objects to have constant acceleration ? Because at any time they will reach the cap somehow. Aren't we talking about light [b]acceleration[/b] when talking about time travel ?
Also as a reason for not being able to travel faster than the speed of light, it is said that nothing is lighter than light (excuse the pun) and therefore nothing can go faster. Then again aren't we talking about acceleration ?
[QUOTE=_Axel;29557918]There are things I don't really understand about astrophysics;
Does light really always travel at the same speed, no matter the repository ?
That doesn't make sense.
Also, if it isn't possible to travel at the speed of light, how is it possible for objects to have constant acceleration ? Because at any time they will reach the cap somehow. Aren't we talking about light [b]acceleration[/b] when talking about time travel ?
Also as a reason for not being able to travel faster than the speed of light, it is said that nothing is lighter than light (excuse the pun) and therefore nothing can go faster. Then again aren't we talking about acceleration ?[/QUOTE]
Einstein postulated that the laws of physics are the same in any inertial reference frame. The speed of light can be derived from Maxwell's equations. If Maxwell's equations are the same in all reference frames, the speed of light must be the same in all reference frames as well.
[QUOTE=_Axel;29557918]There are things I don't really understand about astrophysics;
Does light really always travel at the same speed, no matter the repository ?
That doesn't make sense.
Also, if it isn't possible to travel at the speed of light, how is it possible for objects to have constant acceleration ? Because at any time they will reach the cap somehow. Aren't we talking about light [b]acceleration[/b] when talking about time travel ?
Also as a reason for not being able to travel faster than the speed of light, it is said that nothing is lighter than light (excuse the pun) and therefore nothing can go faster. Then again aren't we talking about acceleration ?[/QUOTE]
Everything has a maximum speed. A human free falling can only go 120mph(?) at most. I'd imagine it'd be similar for space. Except our top speed would greatly increase as there isn't nearly as much friction.
[QUOTE=EastBayWilly;29558156]Everything has a maximum speed. A human free falling can only go 120mph(?) at most. I'd imagine it'd be similar for space. Except our top speed would greatly increase as there isn't nearly as much friction.[/QUOTE]
That's not why the speed of light is the limit.
[QUOTE=_Axel;29557918]There are things I don't really understand about astrophysics;
Does light really always travel at the same speed, no matter the repository ?
That doesn't make sense.
Also, if it isn't possible to travel at the speed of light, how is it possible for objects to have constant acceleration ? Because at any time they will reach the cap somehow. Aren't we talking about light [b]acceleration[/b] when talking about time travel ?
Also as a reason for not being able to travel faster than the speed of light, it is said that nothing is lighter than light (excuse the pun) and therefore nothing can go faster. Then again aren't we talking about acceleration ?[/QUOTE]
You wouldn't be able to have constant acceleration if your treatment of it was purely Newtonian, giving you a linear relationship between velocity and time at constant acceleration, but obviously at relativistic speeds you have to include relativity and use the relativistic mechanics equations, which give you a singularity at v=c.
I'm not quite sure what your problem is. Is it that at a constant acceleration you would eventually travel faster than light if you were simply to use v=u+at?
[QUOTE=EastBayWilly;29558156]Everything has a maximum speed. A human free falling can only go 120mph(?) at most. I'd imagine it'd be similar for space. Except our top speed would greatly increase as there isn't nearly as much friction.[/QUOTE]
Terminal velocity on earth is only due to air friction, and there is almost no particle in space, so I guess there is no maximum velocity due to friction in space.
[editline]2nd May 2011[/editline]
[QUOTE=JohnnyMo1;29557989]Einstein postulated that the laws of physics are the same in any inertial reference frame. The speed of light can be derived from Maxwell's equations. If Maxwell's equations are the same in all reference frames, the speed of light must be the same in all reference frames as well.[/QUOTE]
[QUOTE=petieng;29558471]You wouldn't be able to have constant acceleration if your treatment of it was purely Newtonian, giving you a linear relationship between velocity and time at constant acceleration, but obviously at relativistic speeds you have to include relativity and use the relativistic mechanics equations, which give you a singularity at v=c.
I'm not quite sure what your problem is. Is it that at a constant acceleration you would eventually travel faster than light if you were simply to use v=u+at?[/QUOTE]
Ok, so the fact an object cannot be faster than light is due to relativity itself, not a consequence of Newtonian acceleration.
I thought this was how it was demonstrated, I'd better seek more information about it in order not to get confused.
[QUOTE=JohnnyMo1;29558222]That's not why the speed of light is the limit.[/QUOTE]
I understand light has no mass if that's what you mean.
OP, I'm you from the future. Keep making quality threads, it will get you laid very soon.
Awesome thread!
Dont know if anyone mentioned this. But some american scientist was able to figure out that by using lazers it is possible to distort space and time into a "hole", therefore go back and foward in time, with a machine! he was able to build that machine, and he was geting ready to start the first tests.
I saw this in a documentary some time ago. I think it was from BBC, I looked for it to post here but couldnt find it... does someone know?
This thread confuses and interests me greatly.
[QUOTE=Jetblack357;29566020]This thread confuses and interests me greatly.[/QUOTE]
Basically.
[URL=http://img534.imageshack.us/i/hfgh.png/][IMG]http://img534.imageshack.us/img534/732/hfgh.png[/IMG][/URL]
It wouldn't be a very effective method of time travel, but this is quite an interesting theory.
I remember watching this program by Stephen Hawking about travelling forward in time.
My memory on the subject is a bit hazy, but I'll describe it best as I can.
Imagine you're on a train. This train is going at an incredible speed, it's at about 99.9999(and so on) percent the speed of light. So, what happens if you stand up and try running to the front? Time slows down for you. As you get closer and closer to the speed of light, time slows down to stop you from going at the speed of light.
Sorry about the shitty explanation, someone can probably do a better job than me.
In movies they seem to only travel in light speed. Nothing more.
[QUOTE=zzlawlzz;29572637]In movies they seem to only travel in light speed. Nothing more.[/QUOTE]
Or they don't travel at all and it just seems like they are.
In movies like Back to the Future it amuses me how they perceive time travel. IF it was possible, I think it'd so complicated that you'd need something similar to a MAC cannon as long as the solar system.
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