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Time Travel and Faster than Light
by
JarredB
on 20 Jan, 2016 15:09
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As someone who is still relatively new to Physics and the world of time and space, I have a question for everyone about the Warp drive and what Dr. White is working on. I have read recently that Dr. White and his team at the Eagle works laboratory have had particles accelerate Faster than light. According to Einsteins theory of relativity the only way to go backwards in time is to go faster than light. Is this now becoming a possible? Sorry for my ignorance on the topic like I said I am new and have a somewhat limited understanding of this subject. Thank you all for your help in advance!
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#1
by
1
on 20 Jan, 2016 18:40
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#2
by
JarredB
on 21 Jan, 2016 01:34
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Though it is not really applicable to this forum it is something that should be discussed. The issue here is this. Einstein came to the theory that it is possible if FTL travel is achieved well then that's what would occur. Fact is this, there will always be people who continue to doubt new ideas and scoff at this one, however if a negative net time could be achieved then why not explore those possibilities?
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#3
by
Chris Bergin
on 21 Jan, 2016 01:48
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Welcome to the site's forum Jarred. We are traditionally a "previous, now and immediate future" kinda site, so FTL and such tends to be a bit wild for us, but yeah - the EM Drive and such popularity resulted in this particular section.
Anyhoo, it's all over my head, but I do remember this cool video per FTL and "time travel":
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#4
by
JarredB
on 21 Jan, 2016 02:21
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Hey no problem. This has always been an idea that I have wanted to see come true, reverse time travel. My favorite TV show growing up as a child was quantum leap ( I am aging myself here lol). I think for me the biggest issue is now that we are the closest we have ever been, why isn't this being explored? Dr. Michio Kaku has stated even back in an article in 2003 that the burden of proof now lies on those who say it CAN'T be done. Here is the video I actually saw that states FTL particles may have been discovered at the eagle works lab. It still needs to be peer reviewed. If that is the case then we might be a lot closer than we think. I only post here because I believe that everyone here has a genuine interest in NASA's work and not some crazies on a time travel website. Thank you guys for your patience and answers!
Here is the video
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#5
by
1
on 21 Jan, 2016 02:51
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Though it is not really applicable to this forum it is something that should be discussed. The issue here is this.
I'm all for discussing it, but it's not my site and not my rules. Threads and posts vanish if they stray too far from the overall topic at hand. Just a friendly reminder to keep it at least tangentially related to space flight.
Einstein came to the theory that it is possible if FTL travel is achieved well then that's what would occur.
Not quite. The same equations that say you go back in time also say you get negative energies, imaginary masses, infinite densities, and a whole host of other issues that simply aren't well defined in the real world. It's not a declaration of what would actually happen so much as an understanding that the current math allows for some weird stuff IF (a BIG if) it's possible at all. It's fun, almost romantic to discuss that stuff; but the fact is there's no solid theory (as in,
testable hypothesis) about what would happen to FTL
anything.
The burden of proof on those who say 'it cannot be done' is no less than the burden of proof of those who say it can. Both positions need theory to back it up. Until that happens, a null position of 'we just don't know; let's keep looking' is appropriate. It's neither a yes nor a no, but a humble and respectable acknowledgement that we just don't have the answers yet.
EM drive is interesting (and there's lots of threads with lots of interesting info on this site), but I fear it will simply turn into another pioneer anomaly / neutrino anomaly type situation where an already known effect is has simply been overlooked. Stay tuned. But rest assured, if Eagle Works (or anyone else) actually discovers FTL particles, you'll know. None of this 'may have discovered' stuff; it'll be front page news across the entire planet. Stay hopeful, but remember to stay skeptical.
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#6
by
Stormbringer
on 21 Jan, 2016 14:38
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just have to remember that currently warp drive is not about FTL physics breakers. It is about getting the effect of FTL without actually going FTL. Normally this involves taking or making shorter routes through space than a trip would would take. Now its more complicated than that because many think even if you avoid breaking physics by going the short cut route you still end up with other violations of physical laws.
Dr White has not claimed FTL for his experiments so far and was not directly making that sort of claim. His claim is that his QVPT will create a tiny distortion in the local curvature of space when on and that this could be detected with a sensitive interferometer.
At the face value his conjecture is most certainly true because all energy and mass distorts space time near it according to relativity. So even if he didn't have a coil or whatever he could make such claims for a marble made out of lead. The problem is in measuring it.
Proposal. Calculate a trip to some objective in or near the solar system using normal mechanics and calculate a route using a naturally occurring Einstein geodesic path. give both craft the same mass, propellant, thrust and all particulars launch both at the same time from the same point and record time of arrival apparent velocity and so forth for both craft. the one on the Einstein geodesic should arrive sooner than the one on a regular path. It will in effect have traveled a shorter distance than the one on the regular trajectory. It will have traveled through "warp space" no special engines needed.
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#7
by
JarredB
on 21 Jan, 2016 15:00
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I'm all for discussing it, but it's not my site and not my rules. Threads and posts vanish if they stray too far from the overall topic at hand. Just a friendly reminder to keep it at least tangentially related to space flight.
Not quite. The same equations that say you go back in time also say you get negative energies, imaginary masses, infinite densities, and a whole host of other issues that simply aren't well defined in the real world. It's not a declaration of what would actually happen so much as an understanding that the current math allows for some weird stuff IF (a BIG if) it's possible at all. It's fun, almost romantic to discuss that stuff; but the fact is there's no solid theory (as in,
testable hypothesis) about what would happen to FTL
anything.
Thanks for the heads up. I am just trying to get a full grasp on things as I stated before my knowledge of physics is limited and I honestly believe the answer is staring us in the face. Maybe a case of overthinking?
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#8
by
aceshigh
on 21 Jan, 2016 17:07
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as I understand, any travel above C results in time travel to the past. Even by warp or wormhole.
thatīs because a more correct term for the "speed of light" would be "Speed of Causality".
And remember, Warp Drives and Wormholes do distort SPACE-TIME, not only space.
Alice and Bob can probably explain it to you, but I have a hard time understanding them...
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#9
by
1
on 21 Jan, 2016 18:20
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Maybe a case of overthinking?
Naw, just a case of needing a better source. Unfortunately, there just aren't many shortcuts one can take with understanding relativity. A simple video just won't be able to impart anything more than a cursory understanding of the topic for the average Joe. The math is simply unavoidable for any deeper grasp on the topic. That said, I'm a firm believer in never discouraging anyone who wants to learn, so I'll point you to my favorite intro to the topic.
That book is readable, approachable, requires little exotic math, and is nice and cheap! Makes a great bathroom reader. Won't cover wormholes and warp drive, but it does have a section on photon rockets; and it'll give you a very solid foundation if you want to chase wormholes and warp drives down the general relativity rabbit hole.
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#10
by
KelvinZero
on 21 Jan, 2016 22:22
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I suspect "FTL allows timetravel" is actually equivalent to "1+1=3 allows free energy".
I mean, it is easy to demonstrate how an instantaneous communicator creates timetravel, but for "instantaneous communicator" you have to start with an arbitrary statement to define what you actually mean, such as instantaneous in a specific frame of reference, that seems sensible to a layman but later proves inconsistent from another frame of reference.
Forgetting for a moment how FTL might actually work, I have yet to even read convincing science fiction on how a universe with FTL would appear to the inhabitants. I suspect a good physicist could take any Science fiction scenario and twist it on its head with a few careful experiments.
One reasonable approach to FTL could simply be a virtual reality. Maybe some sort of transcendent computer consumed us in our sleep but left us a sort of video game universe for our amusement. From our POV it seems the physical laws suddenly changed. But what did they change to? IMO you couldn't just add FTL, you would have to take away relativity and now the speed of light is not the same for all observers, and we have a fixed frame of reference, probably an ether, and so on. What established physics would still work without extensive modification? It would actually be an interesting novel because it would draw an a lot of science history.
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#11
by
ChrisWilson68
on 13 Mar, 2016 22:45
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I am just trying to get a full grasp on things as I stated before my knowledge of physics is limited and I honestly believe the answer is staring us in the face.
The people whose knowledge of physics is much less limited (i.e. tens of thousands of professional physicists) believe the answer is not staring us in the face.
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#12
by
Jevans
on 13 Mar, 2016 23:21
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The textbook my Further Special Relativity course worked from was "Relativity Made Relatively Easy" by Andrew M. Steane, which contains a full discussion of electromagnetism and acceleration in SR as well as the normal dynamics and kinematic discussions. My General Relativity course tutor (being Russian) would often point us towards the English translations of Landau and Lifshitz for a complete discussion, but they're not for the mathematically faint of heart - being an experimental physicist I just stuck with the course notes.
I'm afraid that there are no shortcuts to relativity; if you want to know why this sort of thing can't work you do have to put the effort in and get stuck into the maths. Relativity is by it's nature very counterintuitive at points, and things that seem entirely obvious to the casual observer ("Why don't you just try XYZ contrived scenario etc."...) are usually not that obvious at all. On the plus side, it is an extremely elegant theory at heart, so is quite enjoyable to learn about!
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#13
by
JohnFornaro
on 15 Mar, 2016 11:12
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#14
by
martinc
on 17 Apr, 2016 18:17
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just a little comment.. the term 'FTL' is really a sort of approximation, as someone going faster than light will not actually be going faster than light!
the relativistic effects derived from the lorentz formula kick in above 50% light speed or so, and go exponential the closer you get to it
Hence, if you were to go around 70% light speed you would actually be travelling at 186k mps, ie light speed, as the length compression effect would make up the difference. note in actual fact you would not be travelling at 186k mps, but based on how far you travel in a time you measure yourself as the person travelling, that would be your equivalent speed - of course your true speed always was 70% of 186k mps, but the relativistic effects are in force to shorten your journey..
if you were to go at this speed, 70% LS, it would take 1 year to travel a distance of 1 light year
if you were to actually travel at 100% light speed, you would be going infinitely fast through space and time, which is what photons are doing (from their perspective)
To really 'go places' inter-stellar you do need to get close to LS though, for example 99.999999% LS you would travel 100 light years in 0.14 years, so we really do have to get very close to light speed indeed
It's amazing how many people know about the light speed limit, but don't know the other side of that coin is the flexibility inherent in space/time, indeed one can't have one without the other
Martin
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#15
by
1
on 19 Apr, 2016 00:28
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The term 'FTL', unfortunately, has no useful meaning in physics at all; approximate or otherwise. Unless (hopefully, until) our current understanding of the universe changes, 'FTL' holds no domain outside of science fiction.
Martin, phrases like "true speed", "space and time", and mentioning a photons perspective lead me to conclude that you don't quite have a solid grasp on the basics of the theory. You seem genuinely interested in the topic though, so I'll point you towards the book I mentioned earlier in the thread. Focus on the definition and derivation of the spacetime interval. Of course, online resources are also plentiful.
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#16
by
martinc
on 19 Apr, 2016 18:41
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Hi 1, your right FTL sure doesn't have a scientific meaning, the trouble is it's part of the world's language now, unfortunately apart from being innaccurate it makes space travel seem more limiting than it may actually be. granted true inter-stellar travel may not be possible, or it might.. we just don't know..
Yes I did use some non scientific phrases, that is my fault apologies
However the photon's frame of reference is a valid thing to ponder. i'm sure of that, one can speculate on the relativistic effects the photon experiences by going at light speed. This implies a limitless amount of length compression and time dilation. Which we see as 186k miles per second! I think that's pretty awesome.
The truth is, I may not know a great deal, but I also know and smell moralising orthadoxy when I see it.. i'm not saying this about anyone here, but there's a negative, defeatist, no hope type of sentiment that says we can't do things and gets very upset we may have inter-stella travel one day... but that's another story!
ps do you agree with my saying that if you go 70% light speed you will be experiencing some noticable length compression? I can dust off the formula of Lorentz that shows this will get you 1 light year in a year
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#17
by
1
on 19 Apr, 2016 21:55
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Yes I did use some non scientific phrases, that is my fault apologies
Hey, no worries. Non-scientific phrases are normally fine. Relativity, unfortunately, is just one of those places where you really need to be a stickler about the terminology; else, your interpretation of the entire situation can be misunderstood! For example:
I can dust off the formula of Lorentz that shows this will get you 1 light year in a year
This in incorrect, because you've inadvertently mixed units from different reference frames. The '1 light year' part is a spatial coordinate in one reference frame (let's call it the rest frame), and the 'year' is a temporal coordinate in another frame; the rocket's reference frame. As there are an infinite number of possible reference frames, you can see that mixing coordinates between any two (or more!) frames simply has no intrinsic meaning to the system at hand.
There are two proper ways to describe a reference frame:
1) you can describe the system in its entirety using a single frame. For example, you can describe the system in the rest frame if you wish, which would be to say that the rest frame calculates the rocket to move 1 light year in 1.4 years. Or you can describe the system in the rocket's frame, which is to say that the rocket moves 0.7 light years in 1 year. But "1 light year in a year" is right out!
2) However, the preferred way to describe the system, is by using the previously mentioned
spacetime interval. This quantity is constant among all reference frames (at least, allowed reference frames) and by defining it, one can describe the system in all reference frames.
The spacetime interval can be calculated from any one frame, but it's the concept of the interval itself that you should focus on when trying to understand how one frame relates to another. Understanding the formation of this concept (start with the interval of a photon; it's easier) gives a very profound understanding of the foundations of relativity.
Lastly,
However the photon's frame of reference is a valid thing to ponder. i'm sure of that, one can speculate on the relativistic effects the photon experiences by going at light speed.
It's an interesting thing to think about, but only from grand unified theory standpoint. Special relativity simply doesn't define reference frames at C, it uses C as an anchor to define all other reference frames. To see this, look closely at the formula for the Lorentz factor gamma:
Approaching C from the left (V<C) and the formula approaches infinity. But approach C from the right (V>C) and the Lorentz factor becomes imaginary! What does that mean? Well, it means the theory doesn't do well modeling velocities beyond C.
But, more importantly, since the left hand and right hand limits don't agree, it also means that relativity doesn't model velocities AT C either. There simply aren't relativistic reference frames at C, at least not without reworking/expanding/replacing the theory. This is fine; as we know relativity is incomplete. But if we must ponder things (and we must!) our ponderings must be kept within the relm of the theory itself. Else, we're back in sci-fi mode.
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#18
by
aceshigh
on 19 Apr, 2016 21:55
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wouldnīt it be much better if we changed the term SPEED OF LIGHT for "SPEED OF CAUSALITY"? Electromagnetic waves just happen (well, itīs inherent to them) to travel at the Speed of Causality.
Then instead of using the term "faster than light" we would be using the term "faster than causality". Interesting uh?
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#19
by
ChrisWilson68
on 19 Apr, 2016 22:13
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wouldnīt it be much better if we changed the term SPEED OF LIGHT for "SPEED OF CAUSALITY"? Electromagnetic waves just happen (well, itīs inherent to them) to travel at the Speed of Causality.
Then instead of using the term "faster than light" we would be using the term "faster than causality". Interesting uh?
"Speed of causality" has issues too because causality can be much slower. The speed of light is a bound on causality, not the only speed of causality. Light, on the other hand, can't go slower, so it's a better choice.
(Yes, I know, light can go slower when going through a substance instead of a vacuum. But, the light isn't really going slower in those cases, it's just taking a path that isn't quite a straight line. And, even then, the speed is still pretty close to the speed of light in a vacuum, which isn't always true of causality.)
Light is the phenomenon people are most familiar with whose speed is c. In my opinion, it's the best choice for the name of the speed.
