
Speed of light drops to zero at 'exceptional points' - methyl
https://phys.org/news/2018-01-exceptional.html
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stcredzero
Something to head off likely confusion: The Speed of Light is not about the
Speed of Light.

[https://www.youtube.com/watch?v=msVuCEs8Ydo](https://www.youtube.com/watch?v=msVuCEs8Ydo)

Don't get these two things mixed up:

    
    
        - The speed of electromagnetic waves in the local medium
        - The maximum speed our reality allows for causal phenomena

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everdev
Would a wave of light that's stopped be visible?

I'd imagine that light can't reflect off of light. And isn't light only
visible to us when it enters our eyes?

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jstanley
Perhaps you could pass your eye through the light and see a brief flash when
you reach it?

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cjsuk
No because that would require some form of energy transfer. To observe the
state of the system you have to take energy from it. I suspect your very
presence would likely be a big contributor to this not working to start with
too.

Disclaimer: I am not a physicist; merely an engineer.

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peter_d_sherman
"To release the stopped light and accelerate it back up to normal speed, the
scientists showed that the gain/loss parameters can simply be reversed."

Seems like this would be highly useful for _light transistors_ and _signal
synchronization_ in an optical computer...

Or even better... timing _other types of electromagnetic waves_...

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cwkoss
Could this be used to store energy in the form of light?

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Quenty
How about information? Since the light interacts and the speed dropping to 0
depends on properties of both inputs, there’s probably interesting
interactions there.

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Ngunyan
What are the implications of this? Does it mean the speed of light is not
constant after all? Does it mean relativity theory needs to be revised?

> The researchers also expect that this method can be used for other types of
> waves besides light, such as acoustic waves.

They should try it on gravitational waves next time.

