> the camera will collect images of about 20 billion galaxies
If there were intelligent like out there advertising it's presence, are we likely to detect it given the sheer quantity of sources?
If there were intelligent like out there advertising it's presence, are we likely to detect it given the sheer quantity of sources?
Humans are pretty intelligent. Intelligent enough to ask that question, anyway.
So flip it around. If humans were to advertise our own presence to possible species living tens of billions of light years away, how would we go about doing it?
Sadly, even if they noticed and wrote back, our sun will have since burned out, our time in this universe long past.
We‘ve been trying: https://en.m.wikipedia.org/wiki/List_of_interstellar_radio_m...
If we assume it's a broadcast message (a poor guess for Andromeda, but reasonable for further galaxies), with energy projected in all directions, we can use the surface area of a sphere given a distance to get an idea for how much energy would need to be broadcasted to detect a single red photon: A=4πr^2
A = 4π * (2.4×10^22 meters)^2 = 7.238×10^45 m^2 (square meters)
7.238×10^45 m^2 / 221.7 m^2 * 2.8*10-19 J = 9.14136×10^24 J (joules)
Wolfram alpha helpfully says that is "≈ ( 0.024 ≈ 1/42 ) × energy output of the sun in one second ( 1 s L_ )"
Which is better than I expected, honestly.
So, even for detecting life in the closest galaxy, an intelligent species would need to be working on the energy level of output of stars to have a hope of light reaching earth. Not even counting getting above the noise of the rest of the stars, and then sending something identifiable as intelligent.
Imagine something like a DLP chip, but super thin: a reflective foil with tiny baffles that can be opened and closed using something like a simple electrostatic system. Make these into an enormous light-sail like sheet the same radius as the star. Place it between the star and the target system, and you have something akin to a signal lamp using the star as the light source.
You don't need to generate power on the order of a star, you just need to modulate the light field of one. That's a much lower requirement.
Bit of back-of-the-envelope maths is that this is 4*10^12 kg, assuming a sail the radius of our sun, 1 nm thick, and made of aluminium.
That's a huge amount of mass, but conceptually manufacturable if using automated asteroid mining or somesuch.
I feel like I'm making a mistake in my calculations for the energy requirements to toggle the shutters, but it's certainly low enough that embedded solar cells can trivially provide the energy required even if they're tiny and far apart.
There are many (smaller) galaxies much closer than Andromeda: https://en.wikipedia.org/wiki/List_of_nearest_galaxies
There's no reason life would only emerge in large galaxies.
They would therefore be intelligent enough to know to/how to broadcast such a message in a way that can be universally understood.
I expect this project is more geared towards detecting the geometry of the universe e.g. star and galaxy formation and evolution
"We've had to update our model of how galaxies form to include engineering as the most parsimonious explanation for SLAC 79813 and its satellites 79828 and 79829. Light from SLAC 79833 indicates only class O stars whereas both satellites seem to contain only class M stars. Very pretty! But no natural process except precise engineering on a cosmic scale could lead to such homogeneity.
If our models are correct, tidal forces will stretch the two satellite galaxies into orthogonal tidal loops over the next billion years. It takes a species with significantly longer life-span than ours to appreciate the fireworks. But you can watch our simulation."
Such unlikely discoveries might very well start with a photo of the sky.