Skip to comments.Speed of light may have changed recently
Posted on 06/30/2004 1:35:28 PM PDT by NukeMan
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LIGHT NORMALLY moves through a vacuum at about 186,000 miles per second. Nothing in the universe moves faster, and Albert Einstein theorized that nothing ever could. (Click here for some caveats.)
However, light waves can slow down as they pass through a medium. Last year, a research team at the Rowland Institute for Science and Harvard University, headed by Danish physicist Lene Hau, brought light waves down to a 1 mph crawl by putting them through a specially prepared haze of ultracold sodium atoms (http://www.msnbc.com/news/242698.asp)
|Everyone knows of the speed of light as one of the unshakable properties of the universe. It's not surprising, then, that experiments to radically alter light's speed require some serious equipment and hard work. Running such an experiment requires first a careful tune-up and optimization of the setup and then a long period of painstaking data gathering to get a consistent set of measurements. At the Rowland Institute for Science in Cambridge, Mass., our original slow-light experiments typically took place in stints lasting 27 hours nonstop. Instead of breaking for meals, we learned to balance a slice of pizza in one hand, leaving the other clean to flip mirrors in and out on the optics table during 38 seconds of total darkness at a crucial stage of each run.
|Needless to say, I was restless during the week in Copenhagen and eager to get back to Cambridge to continue the light-slowing experiments. In the next month we reached 60 kilometers per hour and decided that it was time to publish. The real payoff for the hard work, prior to those results, was sitting in the lab in the middle of the night and observing the slow-light pulses, knowing that we were the first in the world to see light go so slowly that you could outpace it on a bicycle.
|Late last year we took this process to its logical but amazing conclusion: we brought pulses of light to a complete halt within tiny gas clouds cooled to near absolute zero. We could briefly keep the pulses on ice, so to speak, and then send them back on their way.
As well as being of great intrinsic interest, slowing and freezing light have a number of applications. At sufficiently low temperatures the ultracold clouds of atoms used in our slow-light experiments form Bose-Einstein condensates, remarkable systems in which all the atoms gather in a single quantum state and act in synchrony. New studies of Bose-Einstein condensates will be made possible by, for example, sending a light pulse through a condensate as slowly as a sound wave, which we expect will cause a wave of atoms to "surf"; on the light pulse.
The slow and frozen light work also opens up new possibilities for optical communications and data storage and for quantum-information processing--that is, for quantum computers, which would utilize quantum phenomena to outperform conventional computers. The freezing-light system essentially converts between motionless forms of quantum information and photons flying around at the usual speed of light.
Getting Atoms into a State
Many ordinary materials slow down light. Water, for instance, slows light to about 75 percent of its velocity in a vacuum. But that type of speed reduction, associated with a material's refractive index, is limited. Diamond, which has one of the highest refractive indices of a transparent material, slows light by a factor of only 2.4. Reducing light's speed by factors of tens of millions requires new effects that depend on quantum mechanics. My group produces the conditions for these effects in a cigar-shaped cloud of sodium atoms--typically 0.2 millimeter long and 0.05 millimeter in diameter--trapped in a magnetic field and cooled to within a millionth of a degree of absolute zero.
Sounds interesting. A bit late tonight, I'll try and read it tomorrow. Thanks for the ping!
GOD BOUGHT A FASTER PROCESSOR... and ditched the windows OS...
We were getting too close, so He upgraded back a few centuries ago.
If you've seen one angstrom, you've seen them all.
The fact remains that everything we know about electric and magnetic fields requires electric charges, in other words, a medium, as a focus for the fields. If there is to be a wave, there must be something to wave!
We know that the vacuum of space is teeming with neutrinos. Countless trillions of the ghostly particles pass through each square centimetre every second. Maybe neutrinos constitute the medium of empty space? It makes sense if, as I suggest elsewhere on this site, all particles are composed of orbiting massless electric charges. And neutrinos are the most collapsed form of particle.
This brings us to the speed of light, c. We know from experiment that c varies depending on the medium. More particularly, c varies depending on the electrical characteristics of the medium. The speed of light in a vacuum cannot then be simply declared a universal constant, because a vacuum is not empty space it is filled with vast but varying numbers of neutrinos and some other particles.
It seems more reasonable to suggest that the speed of light is the speed with which an oscillating electrical disturbance is transmitted through a dielectric medium. The speed of light is highest in a medium where the rate of charge polarization in the particles of that medium is greatest. Neutrinos, having the lowest mass, or inertia, of any particle, have the fastest rate of internal charge polarization and response to an electric field. Therefore c is a maximum in a vacuum, paradoxically full of neutrinos.
The notion that c was considerably faster in the past has appeal to both cosmologists and creationists. Both camps have severe difficulties in explaining the observed universe, even with their vastly different time frames, unless things happened much faster initially. Cosmologists would like to see a near infinite speed of light immediately following the big bang and creationists about 10^11 times c. Both are misled by their misunderstanding of the creation myths. It was no accident that a Belgian priest, Georges LeMaitre, proposed the big bang theory, as it came to be known. Science is as much driven by culture and religion as any other human activity.
Proof that the cosmologists are mistaken both in their speculations about light-speed and the big bang hypothesis comes from the very source referred to in the above report the light from a quasar. The above-quoted article says that the quasar is 10 billion light years distant. That is based on the most peculiar big bang theory that the volume of the universe is increasing. It follows the observation that faint objects have their spectrum shifted towards the red. The discoverer of this phenomenon, Edwin Hubble, was careful to not attribute this redshift to the Doppler effect of the velocity of recession of the object, but theorists were not so circumspect. The redshift velocity - distance equation quickly became another of the many dogmatic assumptions of cosmology.
Thanks for the marshmallow demo!
I have to confess that the lead article boggled me severely.
Actually the speed of light (in a vacuum) is a fixed constant that is used as a reference for all other measurements.
No strings attached? What's all this brouaha about String Theory then? Violin tunings?
Rule of debugging: Constants aren't; Variables don't.
Being a Capricorn would make him less of a Cancer. At least may have stuck to the Tropic at hand.
Not exactly a big help for the Young Earth Creationists, is it?
Thanks for the explanation.(125) I didn't know that.
It stands to reason that light would be subject to the law of entropy also
Like , I said in my follow up "Oops, I misread and went another direction. That's an easy mistake to make since scientists around the world have been debating the other direction for over ten years. And frankly this would be the first bit of opposing, as in the opposite direction, theorizing that I have seen. I'll have to wait on peer review for this one. And like I said, the momentum is sliding towards cdk not "c speed up."
The electric universe hypothesis is the brainchild of Australian neo-Velikovskian physicist Wallace Thornhill, by which he seeks to eliminate gravitation altogether and explain all of nature by electromagnetism. The result is some pretty bizzare stuff, including the electric star hypothesis. This hypothesis holds that the source of solar (and stellar) heating is at the suface, and not in the interior. Surface heating is caused by a heavy bombardment of relativisitic electrons accelerated towards the sun by its extremely large excess positive electric charge. There are a lot of reasons to be suspicious of such an argument, which I discuss in this rather long transcribed mailing list message from 1998.
link to Thompson's e-mail exchange with Thornhill: http://www.tim-thompson.com/grey-areas.html
further comments by Thompson regarding Electric Sun theory: http://www.tim-thompson.com/electric-sun.html
In short, the electric sun/plasma Universe stuff is based on the presuppostion of the validity of ancient myths, and its true believers torture science to no end in their efforts to bend it to their will. Thornhill offers no model, only prose, in support of his beliefs.
Contrast this with some of the people on this website who have genuine science credentials; who is more believeable -- some guy from Australia with a BS in 1964, and who has bought into the Velikovskian mythology, or the scientists we have here on FR, who are more than happy to address reasonable questions and explain how science can explain all those things that Thornhill keeps telling you it can't?
At last...the admission we have all been waiting for. ;)
And it works well enough for us to "get from one planet to another".
You know what my vote is...as for the rest, it is much easier to pretend to understand Velikovski, than real science.
Some who follow E.U. are *Saturnists..the premise that the Earth was once in orbit around Saturn..then moved to its current address.
Some who follow Halton Arp join E.U...
many are just tired of vague answers to reasonable questions.
Carl Sagan ..*Super Greenhouse and other quotes just don't cut it anymore..allong with *Dark Matter etc.
Some who follow E.U. are like myself.
See Electrical flow in greater import of working..as a medium..as a catalyst.
My personal interest in posting E.U. links and article excerpts is to invite others to go seek for themselves....draw their own conclusions.
Wal is not the only forwarder I visit...theirs individuals at Goddard...EX and current JPL/NASA types who chat E.U. on the internet on forums.
I have collected PDF H1 assays from Aricebo..with Electrical continuity comment concerning background ...comment on Redshift that leans toward Halton Arp.
As mentioned in some posts..I ran a CNC Plasma gantry..underwater cut..steel and alloy on huge scale.
Nitrogen and Cryo nitrogen base.
did ultrasound testing....X,ray..and welding.
E.U. makes sense to me....yet I do not totally discard *Gravity.
Victor Clube of Armagh observatory and his partners forward *catastrophism as a catylist sequencer in our Solar system.
Nasa has regressed debrie trains and forwarded hypothesis that one or more moons has fragmented in times past.
Nasa even admits Mars had a different orbital configuration in times past.
Today..went googling to refresh on orbitor Galileo.
so ya..Galileo passed to close to IO and got Radiation..then encured chip damage in its computer.
Others comment that Galileo's onboard system wheir damaged by electrical current..which is flowing between Jupiter and Io....5 Million Amphere's I believe the recorded figure.
Each swing by ..by our orbitors only sustains the Electrical reality at work in planets and output of electricity.
You can google on Neptune and Uranus and get all kinds of varied data assay's and depth measures.
yet both have nearly liquid metal slurry's inside whirling at great speed with offset magnetic axis's.
Their is the resonance debate...how many worlds are *capture..which directs debate concerning the accretion disc theory.
E.U. is sure to be wrong at many points.
Its a new construct....I'm comfortable...I'm in for the long haul.
Velikovsky was mocked to derision by the academic.
yet his perception of Catastrophism driving change on worlds..and causing planetary movement is not so stupid after all.
Our Sun/Solar system porpoises up and down the galactic plain.
We are presently some 8 degree's above the dense mid Galactic plain.
For some great length of time our Sun was inside a Spiral Arm of Orion..we are presently just above the inner edge of the spiral arm....having passed thru a disintegrating Giant Molecular Cloud...the young Blue Stars of the Gould belt..part of the disintegrating GMC.
Passage thru boundry zones such as these forward the possibility of energy exchange..gravametric distortions.....bombardment episodes.
From the revision drafts I have read from Arecibo..to NASA/JPL forwards....we are still learning.
we live in a time of revision and awe.
I will enjoy it..and stand with Velikovsky,Clube,Napier..Arp and others......even sarcastic Thornhill : )
Did they put up new signs. I've been driving around at the old speed. This explains why everyone blows their horn and flips me off even though I'm in the right lane.
The speed of light and the color of light are related. If the speed of light has increased, would the old light from galaxies long ago and far away appear to be redshifted?
A darned good question that I hope someone with a good understanding of the physics of light will answer for us.
Bizarre that anyone still, er, waves this around. There is a limit to which light is a wave. The first such limit was noticed in the Michelson-Morely experiments, in which light absolutely refused to act like a wave propagating through a static medium. (One's motion through space should make a difference when measuring the speed of light in such a case and it does not.)
Einstein in 1905 observed that light sometimes still acts more like a beam of little thrown rocks than a wave. It became necessary to resurrect the particle theory with the concept of the photon. It was further observed in various diffraction-grate experiments with one-at-a-time photons that light will act as a wave (propagating on a broad front and forming interference fringes) in some cases and a stream of particles in others depending entirely upon whether one is keeping track of which path the photon takes.
One ignores a lot to still be telling people that light is ripples in some kind of ether.
Agreed. A billion years here and a billion years there and pretty soon you are talking about a lota time.
As best I can figure, the speeding of light in "recent" times (i.e, post-emission along the way) would BLUE-shift the light as we see it here and now compared to how it would have looked to someone near the emitting object back when.
But I should mention that the Michelson-Morely experiment had already proved that you can't just use particle theory, either. You don't get the Newtonian addition-of-velocities predicted by particle theory any more than you get the relative-to-the-medium velocity predicted by waves-in-ether theory. You don't get any difference at all no matter how you're moving or where you aim the light beam.
It was the opening for various theories leading in a few decades to Special Relativity.
Did you follow the Cassini SOI last night?
None of the cable channels showed it so I ended up in my son's room watching NASA TV on the computer.
I take it you're "Holden" out for something to turn modern physics on its head...
So the Bible is right again?
In this you are already proven right. I wouldn't bet on the rest of your post.
It was right after "Drink More Ovaltine" on the decoder ring message.
From the Article:
Some physicists would happily accept a variable alpha. For example, if it had been lower in the past, meaning a higher speed of light, it would solve the "horizon problem".
Cosmologists have struggled to explain why far-flung regions of the universe are at roughly the same temperature. It implies that these regions were once close enough to exchange energy and even out the temperature, yet current models of the early universe prevent this from happening, unless they assume an ultra-fast expansion right after the big bang.
However, a higher speed of light early in the history of the universe would allow energy to pass between these areas in the form of light.
IOW, a faster light-speed (lower alpha) would be useful in the very earliest (pre-inflation) nanoseconds of the universe, yes. Useful in explaining the large-scale uniformity of the universe we see now. However, this does not help what some people are trying to do with this story.
Other things being held equal, a change in the speed of light would change the frequency of arrival of the peaks and valleys in the waveform.
Other things are not exactly equal, however, as it appears space and the light waveforms within have been stretched over time. Assuming the speed of light to be constant, that would red-shift light in transit so that objects appear redder the farther away they are. Since we indeed see a correlation between distance and redshift, it appears the universe has been expanding.
The speed of enlightment has changed....
I have not read it. What does it discuss?
Ah ha! This would explain why I am having greater difficulty driving at night. I just need faster headlights. And all this time I thought I needed glasses or something. hmmm . . . and maybe all this time has not really been that much time.
Must be global warming... Oh, yeah, caused by the Bush Administration. (hee hee)
Actually, it was Heaviside who first calculated the distortion of the electromagnetic fields of a moving charge.
One good thing about the General Theory of Relativity is that it provided an explanation for gravity. It was always a challenge to conventional physics to explain action at at distance without an interaction phenomenon. How does the earth know the sun is over there pulling on us? And how does the sun manage to grab the earth and yank it around without a string between the two?
Heaviside published the first serious post-Newtonian gravitational theory in 1893, his "A Gravitational and Electromagnetic Analogy" in Electromagnetic Theory Vol I. He introduced the concept of mass currents, gravitomagnetic fields, and gravity waves. Not coincidentally, Einstein's GR reduces to Heaviside's theory in the weak field limit.
I think the point of the article and what we need to take away from it is that there is evidence that the speed of light itself is relative and variable. There is evidence that it at one time was faster and at another time was slower than it is now. So the real possibility exists that it was, at one time in the history of this universe, infinitely faster than it is now and that at another point, the brakes could have been put on it and it could have slowed to a level perhaps significantly if not infintely slower than it is now. But at all times the speed of light was the speed of light.
Now if the speed of light was at one time faster than it is now, what would that do to time? If the speed of light is variable, as is suggested by this article, then what, if anything, is constant?
My understanding is very different. Light moves at the speed of light (in a vacuum), and this is true regardless of its color. The color we see is the result of the wavelength, and that's determined by whether the source of the light is moving away from us (stretched out, thus red) or moving toward us (compressed, thus blue).
If light has been speeding up, but not the rate of expansion of the universe, then the degree of redshifting (or blueshifting) probably wouldn't change (I'm winging it here). There is also the independent line of evidence provided by the brightness of Cepheid variables. This always corresponds with observed redshifts, and it was Hubble's big clue that redshift and distance were related. Yet another line of evidence is the absorption of light as it passes through the Lyman alpha forest, which I don't fully understand, but I'm told it independently confirms all the other observations about the distance of stars and the rate of expansion of the universe.
I think it would depend on how the observer is affected by the changed speed of light. Put yourself in the position of a omniscient being who is unaffected by the change. To you, the speed of light has changed and you could measure the difference in light travel time from point A to point B. But to the non-omniscient who are affected by the light speed change, their concept of distance would change with the speed of light. I think the change in distance would be proportional to the change in the speed of light: ie. no net change in measured frequency. Think of the Doppler Effect where only relative motion can be detected (to the first order).
I think a far more interesting concept is the idea of an anisotropic speed of light. Local differences could be measured.
I wish to clear something up that may be confusing, which is my fault. I am a firm believer in evolution. On earlier posts I was simply joshing some of the regular posters on these threads - spicing things up if you will. If I have misled you, forgive me.