High energy light slower than lower energies?

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Discussion Overview

The discussion centers around the observation of gamma rays from Markarian 501 and the hypothesis that high-energy photons may travel slower than lower-energy light. Participants explore the implications of this idea, including potential connections to the Planck length and the early universe, while questioning the validity of existing claims and the need for further data.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that high-energy photons may have a minimum wavelength limit, similar to how massive particles have a maximum speed limit, proposing that a photon's velocity decreases as its energy increases.
  • Another participant requests references to support the claims made, noting that tests over the last decade have yielded negative results regarding high-energy light traveling slower.
  • A different participant points to external sources that discuss the implications of light at the Planck scale, emphasizing that no observations of such wavelengths have been made.
  • Concerns are raised about the significance of findings that claim high-energy light behaves differently, with one participant noting that a 2.5 sigma level of significance is insufficient to support extraordinary claims.
  • Another participant expresses surprise at the lack of data available to either support or refute the claims regarding the velocity of light at high energies.

Areas of Agreement / Disagreement

Participants express a mix of curiosity and skepticism regarding the claims about high-energy photons. There is no consensus on the validity of the proposed theories, and the discussion remains unresolved with competing views on the significance of the observations and the need for further evidence.

Contextual Notes

Participants note the limitations of current evidence, including the need for more data to substantiate claims about the behavior of light at different energy levels and the implications of such behavior in the context of the early universe.

tcthmas
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Hey all, am new here so please go easy on me.

This regards observation of Markarian 501 with the MAGIC telescope. Gamma rays appear 4 minutes after the visible light. That high energy photons (gamma rays) travel more slowly through the "quantum foam" has been suggested, and even more mundane ideas have also been put forward. I would like to know if a theory of mine has any validity or possibility of being correct.

What if a wavelength of light has a minimum limit? Much like the velocity of a massive particle has an upper limit (the speed of light). I would guess this limit to be related to (if not exactly) the Planck length. We have never observed a photon with a wavelength even close to the Planck length. So what I am thinking is that much like relativity says time dilation occurs as you approach the speed of light, the speed of a photon decreases as you approach the Planck length (until you reach v=0 which is obviously the limit). The tachyon theoretically loses energy as its speed increses. Wouldn't the corollary make sense as well? That a photon's velocity decreases as its energy increases?

I would suspect that if this were happening the effects would be unnoticeable until you got to "relativistic" wavelengths like those of gamma rays. This would explain the delay we see from Markarian 501. Obviously, more data would be extremely helpful in determining if any such effect is happening.

Another thought. Inflation was introduced (by hand) to the Big Bang theory in order to explain the uniformity of the Universe we see today. An alternate explanation can be achieved if we assume that light traveled slower in the past. During the first few trillionths of a second after the big bang light would have to be at incredibly small wavelengths and therefore (according to my theory) traveling more slowly than it does today. And when the energy density decreased enough it would suddenly inflate. Your thoughts? Has somebody already thought of this and been proven incorrect? Thanks!
 
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Can you give us a reference to a paper, or at least point us to where you got this information? Tests of this kind over the last 10 years or so have given negative results. If someone has a positive result, it would be revolutionary.
 
http://www.universetoday.com/11889/high-energy-gamma-rays-go-slower-than-the-speed-of-light/
http://www.arxiv.org/abs/0708.2889
https://www.physicsforums.com/showthread.php?t=189175

Agreed it would be revolutionary. It is interesting because nobody can speak of light when the wavelength is on the Plank scale. Nothing like that has been observed. But in the early Universe light must have been on the Plank scale because the Universe was on the Planck scale. For a time.

What I find most interesting about this idea is that it can be verified. But more data is needed and I can't find any. Can anybody help?
 
They only claim that it's significant at the level of 2.5\sigma. That's not significant enough to convince anybody. Extraordinary claims require extraordinary proof.
 
Thanks bcrowell. I agree that more data is needed. With such an extraordinary claim, am surprised that more data is not available either proving or disproving this result. I believe a 2.5 sigma level is significant when speaking of a velocity that should be absolutely constant. However, without further evidence, I agree that it is meaningless.
 
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