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Two galaxies aligned in a way where their gravity acts as a compound lens

(phys.org)
268 points wglb | 11 comments | 16 Nov 24 16:48 UTC | HN request time: 0s | source | bottom
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waltbosz ◴[16 Nov 24 19:38 UTC] No.42158640[source]▶
One fun thing think about is that these two galaxies are only aligned from our perspective in the universe. Viewed from a different location, and they're just two normal galaxies.

Also, imagine having the technology to send signals through the lens and get the attention of intelligent life on the other side.

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kcmastrpc ◴[16 Nov 24 19:47 UTC] No.42158706[source]▶
I’m sure there are plenty of civilizations that have done this, but on the time scale of the universe no one happens to look at just the right moment.
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Voultapher ◴[16 Nov 24 20:35 UTC] No.42159095[source]▶
But wouldn't the size and age of the universe also imply that someone has looked at just the right moment somewhere somewhen.
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drexlspivey ◴[16 Nov 24 20:59 UTC] No.42159276[source]▶
Don’t radio waves weaken proportionally to the square of the distance? No one would be able to detect them past a (relatively) small distance.
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quantadev ◴[16 Nov 24 22:33 UTC] No.42159991[source]▶
The energy density drops off as inverse square law, but the photons go forever. Radio is just photons (light) so it goes forever until it interacts with something it hits. The expanding universe will stretch it's wavelength slightly however.
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1. oneshtein ◴[17 Nov 24 16:46 UTC] No.42165140[source]▶
Regular EM Radio waves are not photons. Photons have special configuration which prevents leaks into surrounding space, while regular radio waves are just waves.
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2. quantadev ◴[17 Nov 24 22:29 UTC] No.42167948[source]▶
Nope. Radio waves are made of photons. All EM waves are made of photons.
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3. oneshtein ◴[18 Nov 24 05:33 UTC] No.42169966[source]▶
Radio waves are not photons. Light beams are not photons.

Light beams (or similar sources of EM waves generated by individual electrons or nucleus) are made by photons. We can record individual photons.

Maybe, radio waves are made of photons, but nobody confirmed that yet, so I can safely say «no». If you can confirm that, Nobel prize is yours.

Are radio waves quantized? Of course, at Planck scale.

Is it possible to form a single 100kHz photon using a macro antenna? I hope for «yes», but I have no idea about «how».

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4. oneshtein ◴[18 Nov 24 05:38 UTC] No.42169986[source]▶
Photons are EM-waves. Are photons made of photons?
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5. quantadev ◴[18 Nov 24 18:12 UTC] No.42175147{3}[source]▶
Maybe check Wikipedia? Because it refutes you in the first sentence on the articles for "radio", "photon", and "light". You're just being pedantic about word definitions to play games with people.
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6. quantadev ◴[18 Nov 24 18:17 UTC] No.42175211{3}[source]▶
Great, now add to that the fact that radio waves are an EM-wave too, and that answers your original confusion.
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7. oneshtein ◴[19 Nov 24 07:57 UTC] No.42180956{4}[source]▶
Maybe you should contribute something useful to discussion.
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8. oneshtein ◴[19 Nov 24 08:00 UTC] No.42180974{4}[source]▶
So, in your opinion, photons are EM-waves, which are made of photons, which are EM-waves, ad infinitum? Or you oppose this?

Please, say something useful.

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9. shadowgovt ◴[19 Nov 24 17:01 UTC] No.42185602{3}[source]▶
The experiment (one of them, that I'm aware of) that cements wave-particle duality is that you can dial the energy of an emitter down until it's emitting one photon at a time and still detect interference in a double-slit experiment. This is impossible if the photons and waves are distinguishable phenomena.

Radio waves are photons; photons are quantum entities that have particle- and wavelike behavior simultaneously.

10. quantadev ◴[19 Nov 24 17:25 UTC] No.42185941{5}[source]▶
I did. I told you Radio waves are made of photons.
11. quantadev ◴[19 Nov 24 17:34 UTC] No.42186049{5}[source]▶
Saying that Radio waves are a particular frequency range of photons is not a tautology. The only one making up tautologies is you.