Faster than the speed of light.

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Discussion Overview

The discussion revolves around the concept of exceeding the speed of light, particularly in relation to theoretical implications and experimental observations. Participants explore the possibility of seeing events before they occur and the nuances of light speed in different contexts, including special relativity.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant references an article suggesting that light can be sped up to 300 times its natural speed and questions the implications of seeing moments in time before they occur.
  • Another participant expresses uncertainty about whether a light beam can exceed the speed of light, noting that massive objects face challenges due to concepts like imaginary mass.
  • A participant describes an experiment where a pulse of light appears to have its output pulse's center occurring before the input pulse's center, attributing this to the dynamics of the medium rather than exceeding the speed of light.
  • One participant agrees with the previous point, labeling the referenced article as misinformed.
  • Another participant clarifies a common misconception regarding the second postulate of special relativity, stating that while the speed of light in a vacuum is not exceeded, group and phase velocities can exceed "c" without transmitting information.

Areas of Agreement / Disagreement

Participants express differing views on the implications of light speed and the interpretations of experimental results. There is no consensus on whether exceeding the speed of light is possible or what the implications of such phenomena would be.

Contextual Notes

Some claims rely on specific interpretations of special relativity and the nature of information transmission, which may not be universally accepted. The discussion includes references to experimental setups that may have limitations or require further clarification.

voodoomagic
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http://science.howstuffworks.com/news-item6.htm

this says that u can speed light to 300 times the natural speed of light, and theoretically one could see a moment in time before it took place.

what do you think??
 
Science news on Phys.org
a light beam itself which exceeds c? Perhaps, probable, I don't really know myself. But something which have mass like you and me would have difficulty going faster than c cos' of imaginary mass and all?
 
yes, i know that I am talking about the seeing a moment in time before it happened
 
I've seen these experiments. A powerful pulse of some duration is sent through a filter that blocks most of the pulse. What comes out is a much shorther pulse, the beginning of which is later than the beginning of the input pulse, but the center of the much shorther pulse is before the center of the input pulse. The output pulse's time duration is completely within the time duration of the input pulse.

To me this is just the dyanamics of the medium. The speed of light is not exceeded.
 
You are correct, Vern - that's a surprisingly misinformed article from howstuffworks.
 
This is very common, the error is to consider that the 2nd postulate of special relativity says that the speed of the light in the vacuum is the top speed. But this is not exactly correct. The 2nd postulate says:

The maximum speed of information transmission is the speed of the light in the vacuum.

In waves, the group velocity and phase velocity don't contains any information about the wave, so both can be greather than "c", and this complains with the 2nd postulate.

See http://www.physicsweb.org/articles/news/8/11/10/1
 
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