Speed of light drops to zero at 'exceptional points' | Hacker News Reader

Speed of light drops to zero at 'exceptional points'

phys.org

44 pointsmethyl9 comments

Something to head off likely confusion: The Speed of Light is not about the Speed of Light.

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

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?

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

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.

"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...

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

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.

I hadn't thought about energy, but storing information encoded in light waves would also be an interesting possibility.

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.

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