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# Speed of Light barrier

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I know that tachyons are hypothetical. But why is it that something travelling faster than light cannot travel slower than the speed of light?

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I know that tachyons are hypothetical. But why is it that something travelling faster than light cannot travel slower than the speed of light?

This is a symmetry issue unless you allow a Tachyon to have a Complex value for Time

{t: t = tx + ity}....

This (not Complex) makes for a bifurcated universe into two realities (subluminal,

superluminal).

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Time is one of the factors but also I assume that it is as difficult to penetrate the barrier of light from the other side (ie superluminal speeds) as from below.

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Time is one of the factors but also I assume that it is as difficult to penetrate the barrier of light from the other side (ie superluminal speeds) as from below.

That was my point. I am sorry I missed this facet. It is a symmetry of a singularity

through the value at the velocity of c (speed of light).

Mass particles CAN-NOT transition "smoothly" (continuously) through the speed of light

from either side. Massless particles (some Bosons) are thought to move at the speed

of light though in theory no one is for sure other the light which is measured to high

accuracy.

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• 2 weeks later...
This (not Complex) makes for a bifurcated universe into two realities subluminal, superluminal).
I've never bothered much about tachyons, but something strikes me about these two realities: they would share all null intervals. Has anybody reckoning on these tachyons ever worked it out?

Let's see... suppose there were a steady flow of gadgets passing us, going toward another galaxy at a near infinite velocity, which is easier than going hardly more than c. Each gadget can detect the signal of photons that I send out, and repeat my signal as it goes along. This repeated signal, also of photons, can be received by non-tachyonic devices in the distant galaxy. With a similar flow of similar gadgets in the opposite direction, the lads over there could even send me their reply. Instant e-mail twixt twain galaxies!

Oh, well... I s'pose some bright one will answer that, in the other reality, our weak forces are the strong ones and EM is the weak... I guess Weinberg's angle is totally different or something...

Massless particles (some Bosons) are thought to move at the speed of light though in theory no one...
One could phrase the first part of this sentence as:

Massless particles (including photons) are thought to move at the speed of massless particles. :eek:

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I've never bothered much about tachyons, but something strikes me about these two realities: they would share all null intervals. Has anybody reckoning on these tachyons ever worked it out?

As it is my conjecture, I am working on it. Explain a bit what you mean by Null intervals. I suspect there

is some connection and still working out what.

Let's see... suppose there were a steady flow of gadgets passing us, going toward another galaxy at a near infinite velocity, which is easier than going hardly more than c. Each gadget can detect the signal of photons that I send out, and repeat my signal as it goes along. This repeated signal, also of photons, can be received by non-tachyonic devices in the distant galaxy. With a similar flow of similar gadgets in the opposite direction, the lads over there could even send me their reply. Instant e-mail twixt twain galaxies!

Oh, well... I s'pose some bright one will answer that, in the other reality, our weak forces are the strong ones and EM is the weak... I guess Weinberg's angle is totally different or something...

A couple of things:

1. It is not clear that photons would/could interact with Tachyons. Doing so can affect causality. That

an example where from the Tachyon's point of view it absorbed this photon before it was sent. Yes,

the upper speed limit would be infinity (or the limit thereof). The energy of such a Tachyon would

increase to 0 from a negative value as the particle was accelerated faster. Their entropy would be

negative. However, a possible interaction is allowed in QED and that is with virtual particles. So the

energy loss in the interaction would seen a debt being paid or loaned out. Time is typically reversed

(though maybe in general time is Complex for a Tachyon as would be mass). So the Tachyon pulse of

Star Trek fame could be created if the proper interactions with virtual particles could be created. Even

neutrinos could be considered here. Lot's o' speculation. :xx:

2. I suspect that the four forces of nature are in both realities spoken above though their behavior are

likely Very different (possibly).

One could phrase the first part of this sentence as:

Massless particles (including photons) are thought to move at the speed of massless particles. :hihi:

I was assuming photons trave at c (already known). What I was saying the Standard Model assumes

the Graviton does along with all the other massless Boson (W+, W-, etc). The Z0 from the Weak Force

is the one that must go slower than light in that it has mass. I learned this in an High Energy Physics

course I took at UCI. What I am saying that we may find that geometry has more to determine what

the speed of massless Boson travel than one universal constant. This might be a bad assumption.

Maybe... :D :naughty:

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Explain a bit what you mean by Null intervals..
You find this in any proper treatment (however basic, but proper) of Special Relativity. Null means ds squared equals zero, massless particles travel along null intervals.

It is not clear that photons would/could interact with Tachyons..
It would be necessary to assume this, in order to avoid the causality paradoxes. This was what I was aiming at, in my loose rant. :naughty:

What I was saying the Standard Model assumes the Graviton does along with all the other massless Boson (W+, W-, etc)..
That isn't an assumption of the Standar Model but of SR, apart from the fact that the SM doesn't really concern itself with gravity. I fail to remember any mention of the graviton in Perkins' textbook or in the original articles about spontaneous symmetry breaking, which gave birth to the SM.

I was assuming photons trave at c (already known). What I am saying that we may find that geometry has more to determine what the speed of massless Boson travel than one universal constant. This might be a bad assumption.
What the second sentence appears to be saying is something essential to SR, i. e. that the minkowskian geometry of space-time determins the velocity of massless particles. I would tend to replace "we may find" with "we have found". To speculate this as being a bad assumption means the same for the whole of relativity, unless you alter the meaning of the word 'mass' in a manner that could hardly be useful.
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Tachions, by theory would have negative mass. By slowing them down towards C they undergo a loss of mass. Think of Lorentz formula in reverse. Unlike normal matter at C they would be massless. In essence, at C their energy vanishes. So for this theoretical form of matter C is a barrier itself. In some ways, the idea of a dual universe mentioned earlier does apply on this. One aspect of Einstein relativity is a sort of beyond the mirror or looking glass universe. In theory nothing prevents this mirror universe from existing. However, an outcrop of modern Brane theory research has shown that such fields tend to produce runaway inflation and in general would literally expand off to infinity even though a lot of the math involved in such theory does seem to require their existance. At some levels this is akin to the issue of say magnetic monopoles which inflation theory in general tended to supply a solution on. If Inflationary BB theory is correct one reason we find no monopoles of the classical type in our universe is because they simply were inflated out of our universe. I suspect the reason tachionic matter is not found is it too was inflated out of our universe.

Under a certain class of theories hyperspace is a sort of tachionic spacetime. It however display a forward moving time signature which while faster than our universe is still casual in the usual sence of the word. This type of field does not superinflate. However, what by theory prevents us from viewing such under those types of theories is the fact that their exists a barrier between that universe and ours. That barrier is rather akin to a domain wall. These class of theories are found themselves in modern brane theory with one example being that of certain varients of Randall-Sundrum Theory.

Basically, Tachyion is anything faster than light. The original idea was particles that moved backwards in time. But at the present time, as mentioned above, this term can also encompass particles that move faster than light and forward in time also.

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Some of your details don't match up to me.

Tachions, by theory would have negative mass. By slowing them down towards C they undergo a loss of mass. Think of Lorentz formula in reverse. Unlike normal matter at C they would be massless. In essence, at C their energy vanishes.
&
In theory nothing prevents this mirror universe from existing.
"By theory" the Lorentz coordinate transformations are singular at v = c and this makes it totally conjectural to extrapolate from subluminal to superluminal reality. Of course this is the reason we can't hope to prove or disprove anything about the very existence of the superluminal, unless we do find examples of extraordinary causality. If you find any, tell me by Friday: a national lottery over here has a jackpot of € 44.300.000 this weekend. You send me the numbers, I play the ticket, we split the prize 50-50. Deal? :naughty:

As for how the mass changes, this is not a Lorentz-invariant description and it dates back to a bit of confusion in the years following Einstein's publication. The word 'mass' is now regarded as a synonym for 'rest energy'. What increases with velocity is total energy. Seen this way, it isn't all that different from Newton's dynamics. Formally, it is actually the exact same thing, just replace 3-vector Galilean relativistic invariance with 4-vector Lorentz relativistic invariance.

Basically, Tachyion is anything faster than light. The original idea was particles that moved backwards in time. But at the present time, as mentioned above, this term can also encompass particles that move faster than light and forward in time also.
Unless you are skeptical of SR the equivalence between existence of time-reversed and superluminal causality is quite established.
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Yes, that should read as kenetic energy in the case of photonlike tachyions. However, by conjecture Lorentz formula applied to a faster than light state has that kenetic energy decrease towards zero as the particle slows down even though, by theory also you are dealing with negative energy to begin with which in itself while not outright forbidden does raise several problems in itself. The worst of these besides say violations of the average weak energy condition is casuality. If one of these particles could exist in our spacetime then in essence you end up with time travel being possible which brings on a whole lot of other problems that most tend to argue against.

Now an altered example of this with a forward moving arrow of time would be a vacuum state where the average energy is less than our vacuum state. By theory such a state would have a higher value for C. In relation to our spacetime a particle there can travel faster than it can in relation to our normal vacuum state. But, even with shifting the value of C there is still a limit on velocity. Some aspects of this are shown in articles dealing with say dual lightcone states, DSR, etc. A reverse example are certain dispersion mediums where the local speed of photons can be slowed down to a near stop. If our vacuum had existed like those mediums then a vacuum state like we exist in now would appear upon comparison of velocities to allow superluminal travel even though casuality is preserved in both states. That being an example of how Lorentz invariance can be preserved even though the mediums and the local velocity of C vary. What has altered is the measuring rods in both cases, not the laws of physics.

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If I am questioning anything it would be that time reversed tachion states actually exist inside of our universe(Notice I do not discount such outside of our universe). Even given some of Kip's articles on time travel via wormholes there is still a very strong argument going about actual time travel in general being possible.

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Perhaps it is a barrier much like absolute zero. In ther realm of existence and the laws of physics that we understand we cannot cool something to zero Kelvin because atomic motion then stops. Perhaps C is the uper limit of our understanding. Not that it is impossible for them to exist, just impossible with the current models we have.

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If I am questioning anything it would be that time reversed tachion states actually exist inside of our universe(Notice I do not discount such outside of our universe). Even given some of Kip's articles on time travel via wormholes there is still a very strong argument going about actual time travel in general being possible.

Nor do I. What I am saying about Tachyons were they to exist is that their spatial coordinate reference

may be in the extra dimension in which in Superstring (or M-Theory) are seen as "rolled-up" may actually

be complex like that of Roger Penrose's Twistor Theory. This could have arose that early in the universe

the dimension split. The outer reality (in 3 spatial dimension and time) and inner unreality (7 spatial

dimensions and time' ) split then creating the inflationary period. I admit I am ending up with 12 total

dimensions and not 11 as in E8 x E8 version of M-Theory containing gravity. Gravity I see could be the

one force that leaks into either reality. The other three forces would have their respective

supersymmetric partners for these interior dimensions. This may have aspects to explain both Dark

Matter and Dark Energy. Just speculation at the moment. I am concocting a test to verify. I am

suspecting it would be done at low energy and not high as in accelerators. I may possibly be done in some novel way not yet thought of. As for "time travel", this may be interesting for a Tachyon as view from

this outer reality as having time be complex in nature (t0 + i * t1).

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Nor do I. What I am saying about Tachyons were they to exist is that their spatial coordinate reference may be in the extra dimension in which in Superstring (or M-Theory) are seen as "rolled-up" may actually be complex like that of Roger Penrose's Twistor Theory. Maddog
It was my understanding that the extra dimensions were mathematical constructs so the calculations were solvable. I'm pretty sure there are only three positional dimentions and the time component for relativistic transforms. The others are used as domains for computation of quantum entities. I realize that's oversimplification but to me, concepts like the Tachyons and external universes are pure specilation.
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I will jump into the conversation out of nowhere but, dont you think that what ever you referance your thoughts(I mean special terminology used to define elements of the arguments) are mental reflections of the observed..?

time for instance.. it may very well be just something we consider that exist but has never existed in the first place..

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It was my understanding that the extra dimensions were mathematical constructs so the calculations were solvable. I'm pretty sure there are only three positional dimentions and the time component for relativistic transforms. The others are used as domains for computation of quantum entities. I realize that's oversimplification but to me, concepts like the Tachyons and external universes are pure specilation.

I agree the 3 dimensions (spatial) for this reality to make up space time. What I am conjecture (this is

speculation) is a separate reality for the extra dimensions (I use 7-spatial ones there). At the moment,

this is all mathematical. I am using 3 and 7 as property derived from Algebraic Geometry. The relationship

between the generalized outer product (vector cross product) and the norm for Normed Division Algebras.

What is unique here is a direct sum provides the Poincare group of 10 dimensions used in string theory.

Time (1) + 3 spatial makes relativistic spacetime (4). Mathematical another possible system is

(7 spatial + 1 scalar) = 8 (another spacetime ?) At the moment I don't know. Of course if one doesn't

consider new things, nothing new get done. Yes, until new ideas become the norm, they often quite

considered unbelievable, unlikely, wrong, etc. It is the road one takes to hone a "new" theory. :naughty:

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F-theory is actually sometimes viewed as 12 dimensional. There also has been some speculation and a bit of theory based upon the idea that our 4th dimension of time could be a composite of say dual timelines merging. Its actually not beyond the realm of possibility at present.

Hyperspace is actually considered its own universe in its own rights by many now. I might also add that the same basic equations used in M-Theory rather support the idea of multiple universes. The 11th dimension out of M-Theory is also rather considered its own spacetime also. Its properties when all the complex math is worked out rather yields a spacetime in which things can move rather fast from point to point. There has even been some articles suggesting that if one could exit this brane we exist on that superluminal travel might be possible. The problem here is one of frames of reference. A bit back some of us did a short bit of study on the idea of a dual frame of reference and found that why this other dimensional frame appears superluminal is simply a matter of the measuring rod being altered. While one could in theory make a journey there in a fraction of a second across vast distances in our universe a large amount of time would have transpired. What we found out is you really never shortcut around C with such a path because the timeline still runs into the future even there. Its more like the whole future timeline is compressed in hyperspace. (See: http://doc.cern.ch/archive/electronic/cern/preprints/open/open-2004-037.pdf ) For a bit of reference on this. Now granted it really does tend to imply more than one time set is at work in this universe on the surface which would lend itself very well to the idea of a 12D set of equations. But, here the timelines are the same so in reality you end up with one time dimension in both universes.

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