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Physicists confirm the incredible existence of "time mirrors" (www.earth.com)

submitted 5 days ago by [email protected] to c/[email protected]

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This sort of time flip has been described as looking into a mirror and spotting your back instead of your face...By carefully adjusting electronic components on a strip of metal, they introduced a sudden jump that reversed the direction of incoming signals...The outcome was a time-reversed copy of the original wave, appearing just as predicted but never before seen with clarity...A wave that can jump to a new frequency and then rewind might open new possibilities for data transmission at different ranges of the spectrum. It could also reshape how certain sensors and imaging systems are designed.

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[-] [email protected] 45 points 5 days ago

Reading that article just left me with more questions :/

[-] [email protected] 57 points 5 days ago

And here are some answers:

https://www.eurekalert.org/news-releases/982119

(a) Conventional spatial reflections: A person sees their face when they look into a mirror, or when they speak the echo comes back in the same order. (b) Time reflections: The person sees their back when they look into a mirror, and they see themselves in different colors. They hear their echoes in a reversed order, similar to a rewound tape. (c) Illustration of the experimental platform used to realize time reflections. A control signal (in green) is used to uniformly activate a set of switches distributed along a metal stripline. Upon closing/opening the switches, the electromagnetic impedance of this tailored metamaterial is abruptly decreased/increased, causing a broadband forward-propagating signal (in blue) to be partially time-reflected, (in red) with all its frequencies converted. (Adapted from Nature Physics)

So kinda like running a sound wave through a flip/reverse filter in audacity and having it switch along the “time” axis.

[-] [email protected] 10 points 5 days ago

An upvote wasn't enough.
Thank you!

I have only skimmed the eureka alert article, but already on the surface it's so much better than... whatever the fuck that originally-linked thing is.

[-] [email protected] 11 points 5 days ago

So thats creepy.. yep..

[-] [email protected] 9 points 5 days ago

The researchers also demonstrated that the duration of the time-reflected signals was stretched in time due to broadband frequency conversion. As a result, if the light signals were visible to our eyes, all their colours would be abruptly transformed, such that red would become green, orange would turn to blue, and yellow would appear violet

This sounds like wave propagation through a given medium, that changes state uniformly, having an instant ‘reflection’ where the wave doesn’t bounce off of anything (so not hitting a wall… it just reverses in ‘time’) and then drops two ‘octaves’ due to energy loss.

[-] [email protected] 8 points 5 days ago* (last edited 5 days ago)

I think the neat part isn't that - it's neat because of the time component doing it.

Yet another strange phenomenon of the quantum realm that seemed impossible but is infact real.

If I remember thinking back to my class on QED, we specifically ignored this solution because there wasn't a real world demonstration of it (which was ironic, as one of my professors was working on the problem in her doctorate).

Makes me want to find that book.

Edit: I might be wrong, I'm thinking of deriving something out of Hilbert Space to Dirac-von Neumann axioms

[-] [email protected] 7 points 5 days ago

So basically you can see your bald spot better. I'm unimpressed.

this post was submitted on 27 May 2025

199 points (98.5% liked)

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