[bearnard1212 (OP)]

With over a hundred billion galaxies in the universe. It is hard for me to believe that there is not at least one other solar system with life. Especially, when some scientists claim that they have already found some exoplanets that can be like Earth.

[Halc]

With over a hundred billion galaxies in the universe.

There are considerably more than that, given the fact that there's no known limit to the size of the universe. If there is a finite chance of life in a given galaxy, then there being life elsewhere is a certainty.

some scientists claim that they have already found some exoplanets that can be like Earth.

Their idea of 'like Earth' is that it has gravity within 50% of ours and perhaps a likely temperature that is within 100°C of ours, each being one of the few things that can be measured of an exoplanet from our distance.

If they mean one that has free oxygen, that doesn't happen naturally. It only happens if there is life already there, and improbably similar to our kind of life. I notice most people that ponder this question (including many scientists) only consider Earth-like carbon/water based life. There are far more possibilities, but most so alien they are hard to conceive without finding (or even recognizing) it first.

[bearnard1212 (OP)]

With over a hundred billion galaxies in the universe.

There are considerably more than that, given the fact that there's no known limit to the size of the universe. If there is a finite chance of life in a given galaxy, then there being life elsewhere is a certainty.

some scientists claim that they have already found some exoplanets that can be like Earth.

Their idea of 'like Earth' is that it has gravity within 50% of ours and perhaps a likely temperature that is within 100°C of ours, each being one of the few things that can be measured of an exoplanet from our distance.

If they mean one that has free oxygen, that doesn't happen naturally. It only happens if there is life already there, and improbably similar to our kind of life. I notice most people that ponder this question (including many scientists) only consider Earth-like carbon/water based life. There are far more possibilities, but most so alien they are hard to conceive without finding (or even recognizing) it first.

But still, there is a possibility that in some galaxy and in some exoplanet there are some forms of life or this planet can be similar to Earth in conditions for living for humans.

[Halc]

But still, there is a possibility that in some galaxy and in some exoplanet there are some forms of life or this planet can be similar to Earth in conditions for living for humans.

By the logic spelled out above, it is essentially a certainty, yes.
The beings living there will probably not be particularly human-like, but perhaps the chemistry will be somewhat similar such that we might be able to eat the local vegetables.

OK, so such a place likely exists. So what? We can't sense it.

If we only consider planets within our visible universe, less than 2.5% of them are within the Hubble radius, and far less than 1% of those are within 2 billion light years distance. So suppose somebody a mere couple billion light years away has fantastic sensing technology and notices Earth has the right atmosphere and environment for them.  They also have ships that can move at nearly light speed.  By the time they get here (4 G-year minimum), the Earth will be a charred smoking husk, certainly not the friendly environment they sensed from afar. Such environments are temporary. Maybe some life here has evolved to a hot dry planet, but it won't be what the visitors came here for.
So the existence of some planet habitable to us without modification is of little interest to humans even if we could somehow know where it is. It has to be reasonably close by.

[bearnard1212 (OP)]

But still, there is a possibility that in some galaxy and in some exoplanet there are some forms of life or this planet can be similar to Earth in conditions for living for humans.

By the logic spelled out above, it is essentially a certainty, yes.
The beings living there will probably not be particularly human-like, but perhaps the chemistry will be somewhat similar such that we might be able to eat the local vegetables.

OK, so such a place likely exists. So what? We can't sense it.

If we only consider planets within our visible universe, less than 2.5% of them are within the Hubble radius, and far less than 1% of those are within 2 billion light years distance. So suppose somebody a mere couple billion light years away has fantastic sensing technology and notices Earth has the right atmosphere and environment for them.  They also have ships that can move at nearly light speed.  By the time they get here (4 G-year minimum), the Earth will be a charred smoking husk, certainly not the friendly environment they sensed from afar. Such environments are temporary. Maybe some life here has evolved to a hot dry planet, but it won't be what the visitors came here for.
So the existence of some planet habitable to us without modification is of little interest to humans even if we could somehow know where it is. It has to be reasonably close by.

Yes, you are right. At that time even if we detact such planet with the help of super powerful telescopes, we cannot define if it`s exactly the planet we are looking for. Not even taking into consideration the fact that we cannot reach it and we have no ideas how to do it.

[bearnard1212 (OP)]

But still, there is a possibility that in some galaxy and in some exoplanet there are some forms of life or this planet can be similar to Earth in conditions for living for humans.

By the logic spelled out above, it is essentially a certainty, yes.
The beings living there will probably not be particularly human-like, but perhaps the chemistry will be somewhat similar such that we might be able to eat the local vegetables.

OK, so such a place likely exists. So what? We can't sense it.

If we only consider planets within our visible universe, less than 2.5% of them are within the Hubble radius, and far less than 1% of those are within 2 billion light years distance. So suppose somebody a mere couple billion light years away has fantastic sensing technology and notices Earth has the right atmosphere and environment for them.  They also have ships that can move at nearly light speed.  By the time they get here (4 G-year minimum), the Earth will be a charred smoking husk, certainly not the friendly environment they sensed from afar. Such environments are temporary. Maybe some life here has evolved to a hot dry planet, but it won't be what the visitors came here for.
So the existence of some planet habitable to us without modification is of little interest to humans even if we could somehow know where it is. It has to be reasonably close by.

Yes, you are right. At that time even if we detact such planet with the help of super powerful telescopes, we cannot define if it`s exactly the planet we are looking for. Not even taking into consideration the fact that we cannot reach it and we have no ideas how to do it.

I wanna add a few words about the possibility of life in other galaxies. There is one theory about Proxima B . I have heard some interesting ideas about Proxima B and some scientists are convinced that this exoplanet might be the second Earth. What do you think about that?

[bearnard1212 (OP)]

But still, there is a possibility that in some galaxy and in some exoplanet there are some forms of life or this planet can be similar to Earth in conditions for living for humans.

By the logic spelled out above, it is essentially a certainty, yes.
The beings living there will probably not be particularly human-like, but perhaps the chemistry will be somewhat similar such that we might be able to eat the local vegetables.

OK, so such a place likely exists. So what? We can't sense it.

If we only consider planets within our visible universe, less than 2.5% of them are within the Hubble radius, and far less than 1% of those are within 2 billion light years distance. So suppose somebody a mere couple billion light years away has fantastic sensing technology and notices Earth has the right atmosphere and environment for them.  They also have ships that can move at nearly light speed.  By the time they get here (4 G-year minimum), the Earth will be a charred smoking husk, certainly not the friendly environment they sensed from afar. Such environments are temporary. Maybe some life here has evolved to a hot dry planet, but it won't be what the visitors came here for.
So the existence of some planet habitable to us without modification is of little interest to humans even if we could somehow know where it is. It has to be reasonably close by.

Yes, you are right. At that time even if we detact such planet with the help of super powerful telescopes, we cannot define if it`s exactly the planet we are looking for. Not even taking into consideration the fact that we cannot reach it and we have no ideas how to do it.

I wanna add a few words about the possibility of life in other galaxies. There is one theory about Proxima B . I have heard some interesting ideas about Proxima B and some scientists are convinced that this exoplanet might be the second Earth. What do you think about that?

Although, many people assume that Proxima B might have the same Environment as Earth. I guess we will have more detailed information when the James Webb Space Telescope will be launched

[evan_au]

other galaxies...Proxima B

We don't have telescopes with nearly enough resolution and sensitivity to study the climate of planets in other galaxies - or to detect radio/laser signs of civilisation there.

Radiotelescopes are already sensitive enough to detect radio signals from a nearby civilisation like ours (in our arm of our galaxy).

However, we don't yet have optical/Infra-red telescopes with enough sensitivity to analyse the atmosphere of planets around nearby stars (nearest 1000 or so).
- This is extremely hard to do with current telescopes (even James Webb), because any light reflected by the planet is overwhelmed by light from the nearby star.
- What is needed is a high-resolution coronagraph, which blocks out the light of the star so the light from the planet can be analysed.
- There have been proposals to build a large space-based coronagraph to find extrasolar planets and analyse their atmospheres. But it almost needs the star-blocking element to be another satellite that flies with the telescope in a parallel orbit. The trouble is, orbits are never parallel - they are always ellipses with  different eccentricity and velocities. And maneuvering two satellites takes a lot of reaction mass.

See: https://en.wikipedia.org/wiki/Coronagraph#Extrasolar_planets

[Halc]

There is one theory about Proxima B . I have heard some interesting ideas about Proxima B and some scientists are convinced that this exoplanet might be the second Earth.

Not sure how they conclude this. The thing has greater mass than Earth, so probably greater surface gravity. It is known to have solar wind pressure of 2000 times that of Earth, blowing away any atmosphere, and is so close to its star that it's likely tide locked.
This hardly seems to qualify it as 'the second Earth' other than the fact that it's sort of nearby and perhaps has a zone that has suitable temperatures, but otherwise it's a hostile fatal radiation bath.

[donyaison]

I believe it is likely that there is life on other planets somewhere else in the universe. My main reasoning is the same as anybody else's, with so many systems and planets, it's hard to believe that earth is unique enough to be the only one with life, especially considering the diversity of ecosystems and extremophiles just on this planet.

I, at the very least, believe extraterrestrial life has existed or will at some point, independent of life on Earth, like not germs that land on another planet from Earth or Earth's seed for life if it landed here from elsewhere.

If we're talking about technologically advanced, space faring life, then I guess I'm agnostic on the subject and can't really give it true consideration. I do love thinking and reading about it in various sci-fi, though.

[TommyJ]

Together with Fermi Paradox and SETI [may have] overlooked messages, commonly discussed within the extraterrestrial life subject, there are some more spots that could be considered.

1. One based on Bayesian probability, the probability of one particular hypothesis being valid compared to all the possible hypotheses. Assumption of starting point has a 50/50 probability. This is a contrast to the question of life's emergence: the data is good enough to conclude that the common-life scenario is more likely than the rare-life scenario.

Also Stephen Hawking mentioned that we might start our life occurrence in the universe thinking by making a hypothesis: “the universe exists for life being here” and “if not our planet, why another one”.

2. Life evolution and reproduction is not following common entropy, it creates an order, but this should result in the intelligence self-destruction (assuming analysis of human evolution).

3. Do we have a chance with AI? Which could be believed/predicted as another evolution phase of humankind by Friedrich Nietzsche. Another intelligence form, that doesn’t need DNA reproduction and probably entropy contradiction.