Comments on: Point-Five Past Lightspeed

By: Dan Katz

Dan Katz — Sat, 23 Jun 2012 22:14:57 +0000

To set the record straight, everything in the universe travels through spacetime at the invariant speed c. Light itself is believed to travel through space at c, with zero travel in the time dimension. Earthbound humans, however, “use up” most of their speed allocation in the time dimension. For present purposes, light travels through space at exactly c, regardless of medium; it is not true that light slows down or speeds up depending on medium. Now, phase velocity is defined as c/n, where n is the frequency dependent index of refraction, but this is physically different than the speed of light. Phase velocity is due to the superposition of the direct wave with secondary waves radiated by electric charges within the medium; all of these constituent light waves travel with speed c. The secondary waves may be either retarded or advanced in phase relative to the direct wave, corresponding, respectively, to resultant phase velocities less than or greater than c. According to the Ewald-Oseen extinction theorem, the effect is as if the direct wave incident on the medium is extinguished and replaced by a wave of the same frequency but with a phase velocity c/n characteristic of the medium (this is the origin of refraction).

By: Richard Rose

Richard Rose — Thu, 01 Dec 2011 19:58:41 +0000

Hi;
It occurs to me to wonder if the real constant of the universe is actually the speed of nutrinos, and that the speed of light is only very close to that speed….with our current “observer biases” we would conclude that lightspeed actually was the universal constant, and that any variances we’ve observed in our experiments to test it, were our own errors. Would any of the math we’ve based our calculations on, be significantly different if lightspeed were only a few nanoseconds out?

By: Osiris

Osiris — Sun, 20 Nov 2011 17:52:37 +0000

Many here make the statement about ‘c’ being the so called speed of light …in a vacuum. However, let us make first the statement about terminal velocity. That is terminal velocity of a falling object in our atmosphere, which is about one hundred and twenty miles per hour. We can prate all we want to about the falling velocity being [integral]{{d(accel vector)/dt} + V0} whose resolution in three dimensions is -32 ft/(sec^2) which after a few seconds seems to yield fantasy…until we start to have to accept the reality that the Reynolds and d’Arcy Weisbach equations concerning the behavior of viscous fluids give rise to forces countering the gravitational acceleration differential equations of Newton. The acceleration forces are countered by the resistance forces in the viscous medium, air, through which any earthbound falling matter ‘falls’. In space is no different. Space is NOT empty, and has Reynolds, Froud, and other maybe undiscovered viscous resistances as well. There is no perfect vacuum….anywhere, so ‘c’ really is an imaginary number. As lightspeed is variable depending on media, its density, and other characteristics of media; and can actually be ‘stopped’ in certain circumstances like in Bose-Einstein media; so it can also be variable in supposed vacuums that are really highly dispersed plasmas, gases, liquids, and solids, and other states of matter yet undiscovered. Therefore what we perceive as ‘c’ is really an average of many differences on the resolution in multidimensional space of the discontinuous partial differential equations in many unknowns governing its travel from source to observer. Statistics! That is what has yielded what we popularly want to call ‘c’, because until we find something better, many of us ‘want to believe’ in Dr Einstein’s work simply because it has worked well so far, and one never gets fired, loses tenure, loses professional face, or loses promotability…for continuing to robotically support his work. For all we know, the functions governing ‘c’ may be akin to the tangent ratio, hyperbolically tending to infinity as one approaches true vacuum through decreaingly positive values.

By: spaceagesoup

spaceagesoup — Sun, 20 Nov 2011 08:20:47 +0000

The light-speed barrier provides a useful framework for considering how we observe phenomena. I think it is reaching to think that the effect extends to all objects/phenomena in a physical sense, it only provides for considering how a participant OBSERVES light from speeding objects from various frames/perspectives (just the light – like how we would observe objects falling past an event horizon – not the object).

We tend to photocentric in defining our understanding of nature, but should realise that photons are the limiting factor, and of course their maximum (or perceived maximum) is the upper limit for phenomena observed using photons.

By: Lee Lofgren

Lee Lofgren — Fri, 18 Nov 2011 19:48:22 +0000

You are right that speed in [only] one sense is not limited to the speed of light, and that has to do with the rate planets move away from each other due to the expansion of the universe, however, with that exception set aside.
The point you make about speed being relative is exactly the point Einstein made, and like you, he did not believe his own conclusions either. One thought experiment you can do is as follows. Two observers, one on a speed-of-light ship, and one just floating around (stationary to both ships) are watching another speed-of-light ship coming toward the first one. The observer on the speed-of-light ship should see the other ship as traveling at twice the speed of light, whereas the outside observer should see each going at the speed of light but in opposite directions.
What if, both observers saw the other ship as only going the speed of light, rather that the ship based observer seeing the other ship at twice the speed of light?
What would be the ramifications.
One thought is that since Speed = Distance/Time. If speed is fixed, but distance is varied, time must also vary.
If this were true, is there anyway to prove it?
We don’t have to actually get to the speed of light to test this, we only have to be very accurate.
One experiment that has been done is to put synced atomic clocks on 2 planes, one going the direction of the earth, and one opposite so that they are traveling at substantially different speeds over the same distance.
If speed is linear then the clocks should stay in sync. If speed plateaus at some value then speed is not linear and the clocks should be out of Sync. Here is the experiment http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html

By: Mr.Temple

Mr.Temple — Wed, 19 Oct 2011 23:57:31 +0000

Phaedrus, I think you’re bumping into the very unintuitive reality that light’s velocity is not additive. All kinds of strange predictions come out of that supposition, some of which you’ve alluded to (some even weirder ones which you haven’t). The thing is that *every* experiment to test these strange predictions of relativity has wound up confirming them to be true.

Much of modern technology (everything from CRT televisions and computer monitors to GPS devices) simply wouldn’t work if not for these bizarre truths of the universe which relativity reveals.

I sympathize that it may make no sense, but you should bear in mind that, unlike the understanding we have developed about the everyday world around us, our species has had no need to develop an innate intuition or common sense for relativistic phenomena.

By: Phaedrus

Phaedrus — Wed, 19 Oct 2011 08:26:01 +0000

The whole idea that there is some speed limit on all things, is in my opinion, totally absurd nonsense! What is “speed”? SPEED is distance per time IN RELATION TO SOMETHING. There is no such thing as speed without a context. The statement that nothing can go faster than the speed of light hardly makes any sense. All speed is relative to something. There are quite likely objects on the outer reaches of the universe that are certainly at least approaching the speed of light in relation to this planet. So that means, we, on this planet are also approaching the speed of light in relation to something else. So does that mean we are restricted in someway, from going too much faster in a direction away from this distant object on the other end of the universe which is speeding away from us near the speed of light? Since to go faster than the speed of light is not allowed? Remember, we can’t go the speed of light, because as you approach the speed of light, well, your mass goes to infinity! And the energy required goes to infinity! And oh yea, it means our time goes slower and slower. So if there is something on the other end of the universe trying and trying to approach the speed of light away from us, that means we are going faster and faster in relation to it and our mass is approaching infinity, OH MY!!! The universe is going to explode!! Or at least we will, because after all, you can’t have infinite mass! You can’t go the speed of light and certainly cannot exceed it, irregardless of what this thing is that we are measuring the speed with respect to! It could be a piece of dust zipping along out a billion billion billion light years away!!

Oh, but the relativists will look to their sacred texts, and say, no, no that’s not what God, er, I mean, Einstein said. He said that that relative to those objects we would be restricted from going faster than light, and our mass would approach infinity. As observed by that distant object. Oh, ok, then gee it all makes sense now.

By: Krishna

Krishna — Tue, 27 Sep 2011 03:56:28 +0000

Beautiful article. Pauli’s Ghost once again smiling and throwing new challenges. These challenges makes Physics and science more interesting and attract young minds.