How far can a message be sent toward the centre of the sun with a laser?
Also… Is there a satellite which can look for it’s own reflection in distant alien mirrors? got to be a good method of looking apart from the need for millions of mirrors and the time delay…
You want to send a message into the depths of the sun? No normal laser is going to penetrate very far, the sun’s material is very ionized (plasma), and not transparent to laser frequencies. I’d think some long wave radio frequencies may work for near surface transmissions, but no electromagnetic radiation is going to make it to the center of the sun. Try neutrinos.
I don’t know what about that second idea. Do you suppose aliens have set up arrays of mirrors in their system for some reason? And why would you try to have your own mirror to detect reflections? That would double the time lag of seeing anything, aside from the near zero chance of even bouncing photons between two mirrors in different star systems.
Alien mirror arrays will be focussed for their own uses. Very little if any “leakage” will occur (it is not efficient to set up mirrors to direct their reflections at random stars).
If you are building a launch laser and considering using it for communication, an active signal is more sensible. That way, the aliens can capture it, and answer directly. (They will notice if you are bathing their system with laser light in the hopes of getting a glint off one of their mirrors - might as well send a “Howdy, neighbour” while you are at it.)
Of course, they may respond with a Conquest Fleet, but no one ever said the Universe was a friendly place.
(Lasers are a lousy way to communicate with sundivers. And the native solarians are no more willing to talk with us “freezepops” than we are willing to learn slime-mold language. Just saying.)
OK. There’s a reflecting mirror on the moon, and it will bounce back a pulsed laser signal to an observatory, but the return pulse is only detectable with specialized equipment, its too diffuse otherwise (That’s how it was described on Mythbustes, hopefully that’s an adequate citation.) Based only on that, I can’t exclude a satellite in low Earth orbit from seeing it’s own reflection, but I doubt it. Your scenario of banks of mirrors spaced appropriately for intergalactic communication is just not possible. Like others have said.
… kind of an interesting question, but are you expecting to find aliens living in the center of the sun or something?
Or are you really looking for "can you use a laser to communicate *through *the sun? Which, IMO, is a much more practical question.
I read the OP as: If a laser was shone towards the Sun from some location eg. the Earth or maybe an orbiting satellite, how far would it get before the solar wind stopped it? Ie, how close to the Sun would it get? Don’t have a clue myself…
That was my interpretation. Interesting question. I have no idea, of course.
The solar wind is transparent, and so wouldn’t stop the laser at all.