5 ms·

no matter how advanced the civilization is, proxima centauri will always be 42 trillion kms away. Our civilization in current stage is not even close to 0.1% th

no matter how advanced the civilization is, proxima centauri will always be 42 trillion kms away. Our civilization in current stage is not even close to 0.1% the speed of light but lets say your advanced civilization goes at 99% the speed of light, still doesnt change the fact they need 4.25 years approx to reach earth. Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. So basically you are asking them to take a shot at coming to the solar system on a 5 yr trip when they have no idea what is found here. Now extrapolate the numbers for the average 100 light year trip between 2 points on our galaxy and you ll quickly realize why we dont have aliens

dash2 2y ago
> Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. How come we’re making progress on this without a 1bn km telescope?
- 986aignan 2y ago
  And even that notwithstanding, they could use a solar foci telescope. It's kind of a pain to orient, but it /does/ give you extreme magnification.
globular-toast 2y ago
If they came here and back at .99c it would be ~70 years "time debt"[0] for them (meaning 70 years would have passed for their relatives back home). [0] Terminology from Dan Simmons's Hyperion. Would also recommend Joe Haldeman's The Forever War for more time dilation themes.
glimshe 2y ago
Where did you get the 1bn km number? I'm asking it seriously, I'd like to better understand how to calculate these things.
- vivzkestrel 2y ago
  some calculation about resolution of the telescope to be able to see cities and people of another planet from a 100 light years away at the minimum. I forgot the exact calculation but it ll need a humongous sized telescope mirror
npc_anon 2y ago
On a similar note, humans cannot colonize the galaxy. Sending a single message across would take thousands of years. Instead a human ancestor would split into various individual species. When you think of it, light speed is really slow. Even on Earth we are capped by it.
D-Coder 2y ago
If their lifespan is 10,000 years, a five-year trip to exotic backwater Earth would be just a vacation.
floxy 2y ago
Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission (with 1 km resolution) https://arxiv.org/abs/1802.08421 https://arxiv.org/abs/1802.08421 ...and someone made an awesome video about it: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI

dash2 2y ago

> Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. How come we’re making progress on this without a 1bn km telescope?

986aignan 2y ago
And even that notwithstanding, they could use a solar foci telescope. It's kind of a pain to orient, but it /does/ give you extreme magnification.

globular-toast 2y ago

If they came here and back at .99c it would be ~70 years "time debt"[0] for them (meaning 70 years would have passed for their relatives back home). [0] Terminology from Dan Simmons's Hyperion. Would also recommend Joe Haldeman's The Forever War for more time dilation themes.

glimshe 2y ago

Where did you get the 1bn km number? I'm asking it seriously, I'd like to better understand how to calculate these things.

vivzkestrel 2y ago
some calculation about resolution of the telescope to be able to see cities and people of another planet from a 100 light years away at the minimum. I forgot the exact calculation but it ll need a humongous sized telescope mirror

npc_anon 2y ago

On a similar note, humans cannot colonize the galaxy. Sending a single message across would take thousands of years. Instead a human ancestor would split into various individual species. When you think of it, light speed is really slow. Even on Earth we are capped by it.

D-Coder 2y ago

If their lifespan is 10,000 years, a five-year trip to exotic backwater Earth would be just a vacation.

floxy 2y ago

Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission (with 1 km resolution) https://arxiv.org/abs/1802.08421 https://arxiv.org/abs/1802.08421 ...and someone made an awesome video about it: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI