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In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habita

In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of sun-like stars and red dwarf stars within the Milky Way Galaxy.[2 https://en.wikipedia.org/wiki/Drake_equation#Current_estimates https://en.wikipedia.org/wiki/Drake_equation#Current_estimat... So at a rate of 40 billion earth like planets in each galaxy. Deep field from Hubble turned up 125 billion galaxies. 125 billion * 40 billion = 5e+21 That means that over billions of years there is allot of time for life creation and death within the universe.

Koshkin 6y ago
That would be on average 1 out of every 10 stars - hard to believe.
- ksherlock 6y ago
  Our solar system has Earth and Mars. Venus is on the edge of the habitable zone. Had the asteroid belt formed a planet, it would be on the edge as well.
floxy 6y ago
Two trillion galaxies (2e12) according to: https://phys.org/news/2017-01-universe-trillion-galaxies.html https://phys.org/news/2017-01-universe-trillion-galaxies.htm...
flippyhead 6y ago
Right, but, what does it all mean?
- 01acheru 6y ago
  Maybe nothing, but just the fact that we're talking about it is something, IMHO.
- todd_t 6y ago
  It means we won the cosmic lottery.
  - mmazing 6y ago
    Or - there's tons of lottery winners and we're bad at finding them.
  - pklausler 6y ago
    If qualifying as a technical civilization can be defined as being able to launch a self-replicating interstellar probe (a/k/a a Bracewell-von Neumann probe), we can be confident that our galaxy has not yet had one. Once those probes are out there, they'll saturate the galaxy permanently; and once a technical civilization can launch one, it'll happen eventually. A modern billionaire could probably fund such a project now.
    - jakear 6y ago
      > We can be confident that our galaxy has not yet had one How can we be confident of that? For all we know the Cambrian explosion was precisely that.
- 2112 6y ago
  There might be only one way to find out ; https://en.wikipedia.org/wiki/Magic_mushrooms https://en.wikipedia.org/wiki/Magic_mushrooms
credit_guy 6y ago
Whenever we talk about alien life, we should always, absolutely always limit our discussion to the Milky Way. Any alien life outside of the Milky Way will remain completely irrelevant for us for any timespan that has any meaning for us as humans. Just hearing "You had me at Hello" back from the Andromeda galaxy would take 5 million years. 5 million years ago humans and chimps were still not distinct species.
- jonnypotty 6y ago
  Our understanding of the universe could be arbitrarily rudimentary which means actually advanced technology, say that which improves somewhat like ours for, say, a million years would just look like magic to us.
- DesiLurker 6y ago
  no necessarily, assuming a galaxy wide expanding type II civilization that converts every star it encounters to a Dyson swarm as the tracked intelligent civilization. they will easily take a few 10s of Million years to colonize their galaxy. in this process we should be able to see such transformation 'in real-time' via changing radiation signature of the region. Fermi-paradox is paradox for a reason!
  - credit_guy 6y ago
    > Fermi-paradox is paradox for a reason! The Fermi paradox is just a way to have fun at parties (or over the internet, especially on HN). There are so many possible solutions to the Fermi paradox. But each solution has questions, and answers, and more questions and more answers. That's why it's so fun. But it's not that deep. To the point, the Dyson swarm is virtually guaranteed to not be used by any advanced civilization. Once a civilization tames nuclear fusion (and we are on the brink of doing so), then harnessing the energy produced by the local star via a bunch of solar panels becomes just a clunky way of getting energy. Controlled nuclear fusion can be many, many orders of magnitude more productive and convenient compared to solar energy. A star is indeed a massive fusion reactor, but it's a very slow one. Our Sun in particular produces about as much energy per pounds as the heat produced by the fermentation of manure. ITER is projected to produce hundreds of millions of time more. And ITER is just the beginning. Sure, the Sun contains most of the matter in the solar system, but plenty exists in the planets. We could use hydrogen stripped from Jupiter to produce trillions of times more power than a Dyson swarm could produce, and we can have that in a portable form that we could take with us in interstellar travels. Bottom line, whoever is looking to find Dyson spheres out there in the sky, is simply wasting time.
gbrown 6y ago
Don’t forget that we can put a lower bound on the size of the actual (ie, not just the observable) universe and it’s many times greater in size. It could even be infinite, but at the very least it’s larger than we can see.

Koshkin 6y ago

That would be on average 1 out of every 10 stars - hard to believe.

ksherlock 6y ago
Our solar system has Earth and Mars. Venus is on the edge of the habitable zone. Had the asteroid belt formed a planet, it would be on the edge as well.

floxy 6y ago

Two trillion galaxies (2e12) according to: https://phys.org/news/2017-01-universe-trillion-galaxies.html https://phys.org/news/2017-01-universe-trillion-galaxies.htm...

flippyhead 6y ago

Right, but, what does it all mean?

01acheru 6y ago
Maybe nothing, but just the fact that we're talking about it is something, IMHO.
todd_t 6y ago
It means we won the cosmic lottery.
- mmazing 6y ago
  Or - there's tons of lottery winners and we're bad at finding them.
- pklausler 6y ago
  If qualifying as a technical civilization can be defined as being able to launch a self-replicating interstellar probe (a/k/a a Bracewell-von Neumann probe), we can be confident that our galaxy has not yet had one. Once those probes are out there, they'll saturate the galaxy permanently; and once a technical civilization can launch one, it'll happen eventually. A modern billionaire could probably fund such a project now.
  - jakear 6y ago
    > We can be confident that our galaxy has not yet had one How can we be confident of that? For all we know the Cambrian explosion was precisely that.
2112 6y ago
There might be only one way to find out ; https://en.wikipedia.org/wiki/Magic_mushrooms https://en.wikipedia.org/wiki/Magic_mushrooms

credit_guy 6y ago

Whenever we talk about alien life, we should always, absolutely always limit our discussion to the Milky Way. Any alien life outside of the Milky Way will remain completely irrelevant for us for any timespan that has any meaning for us as humans. Just hearing "You had me at Hello" back from the Andromeda galaxy would take 5 million years. 5 million years ago humans and chimps were still not distinct species.

jonnypotty 6y ago
Our understanding of the universe could be arbitrarily rudimentary which means actually advanced technology, say that which improves somewhat like ours for, say, a million years would just look like magic to us.
DesiLurker 6y ago
no necessarily, assuming a galaxy wide expanding type II civilization that converts every star it encounters to a Dyson swarm as the tracked intelligent civilization. they will easily take a few 10s of Million years to colonize their galaxy. in this process we should be able to see such transformation 'in real-time' via changing radiation signature of the region. Fermi-paradox is paradox for a reason!
- credit_guy 6y ago
  > Fermi-paradox is paradox for a reason! The Fermi paradox is just a way to have fun at parties (or over the internet, especially on HN). There are so many possible solutions to the Fermi paradox. But each solution has questions, and answers, and more questions and more answers. That's why it's so fun. But it's not that deep. To the point, the Dyson swarm is virtually guaranteed to not be used by any advanced civilization. Once a civilization tames nuclear fusion (and we are on the brink of doing so), then harnessing the energy produced by the local star via a bunch of solar panels becomes just a clunky way of getting energy. Controlled nuclear fusion can be many, many orders of magnitude more productive and convenient compared to solar energy. A star is indeed a massive fusion reactor, but it's a very slow one. Our Sun in particular produces about as much energy per pounds as the heat produced by the fermentation of manure. ITER is projected to produce hundreds of millions of time more. And ITER is just the beginning. Sure, the Sun contains most of the matter in the solar system, but plenty exists in the planets. We could use hydrogen stripped from Jupiter to produce trillions of times more power than a Dyson swarm could produce, and we can have that in a portable form that we could take with us in interstellar travels. Bottom line, whoever is looking to find Dyson spheres out there in the sky, is simply wasting time.

gbrown 6y ago

Don’t forget that we can put a lower bound on the size of the actual (ie, not just the observable) universe and it’s many times greater in size. It could even be infinite, but at the very least it’s larger than we can see.