What is "Earth-like"?

[pErvinalia]

rainbow and 42 sitting in a tree,
k-i-s-s-i-n-g.

[JimC]

Oh shit, another name change. Being a stubborn old bugger, I will continue to address him as rEv...

[rainbow]

rainbow and 42 sitting in a tree,
k-i-s-s-i-n-g.

Never before has someone been so wrong that the universe has had to wrap itself around and make opposites meet.

Well done, Tiger.

[pErvinalia]

You're wronger than a wrong thing.

[rainbow]

[Forty Two]

Ok, I just looked at your link, and it's an argument from semantics. I am clearly using the phrase in the second meaning described in the link, although, the correct way to state it is: "Absence of evidence is not proof of absence".

I've previously pointed this out -- for example when I said "A better phrasing is "absence of evidence is not conclusive proof of absence." But, that doesn't sound as catchy." You then continued your nonsense.

"argument from semantics" -- lol -

Of course it is an argument from semantics. I clearly used it in the sense of proof. And it is logically sound with that usage.

If you "clearly used it in the sense of proof" why did you continue to maintain your position after I illustrated the difference between evidence and proof?

Because I don't read all of your posts. They are invariable torturous.

LOL - that doesn't make it any better. You failed to read a rather short (about 100 words) post, and declared me "so far from wrong it's not even funny..." or words to that effect. You can't declare an argument wrong which you haven't read, especially when that argument makes the very distinction you later try to rely upon to dishonestly squirm your way out of being completely wrong.

[Forty Two]

Word to the wise now when dealing with you. When arguing with eRvin, always get an affirmation that he's actually read your argument. It seems quite likely that he simply bleats on and on without even bothering to try to understand what you're saying.

No point in engaging perVin on this topic.
He knows nothing and isn't prepared to admit it.

Indeed.

[mistermack]

If they detected a planet like Mars or Venus, they would wet themselves. But we know what they are like.
Nothing to get exited about, till they see the signature for oxygen in an atmosphere. Now that WOULD be Earth-like.

We have the Moon and Mars to play with. But we're years away from mastering those.
To send a manned mission to the nearest star would take between forty and a hundred thousand years, if they decided to spend the money right now. So it's of academic interest only at present.

[Forty Two]

If they detected a planet like Mars or Venus, they would wet themselves. But we know what they are like.
Nothing to get exited about, till they see the signature for oxygen in an atmosphere. Now that WOULD be Earth-like.

These discoveries are awesome in and of themselves. Nothing to get excited about? Well, if one has any understanding of what we knew just a few short decades ago, and what these discoveries mean to the advancement of our knowledge of the universe, one would find them more than exciting.

We have the Moon and Mars to play with. But we're years away from mastering those.
To send a manned mission to the nearest star would take between forty and a hundred thousand years, if they decided to spend the money right now. So it's of academic interest only at present.

A manned mission to a place 4.5 light years away is not feasible right now. But, a very small observational craft, hurled there as fast as we can get it to go, would, quite possibly, be able to get us information on that solar system in a generation. That represents a tremendous shrinking of the universe as we know it. To even be able to talk about sending craft to that system is monumental.

We should be doing it. We should be doing it as fast as we can.

[rainbow]

If they detected a planet like Mars or Venus, they would wet themselves. But we know what they are like.

They?

Who are "they"?

Nothing to get exited about, till they see the signature for oxygen in an atmosphere. Now that WOULD be Earth-like.

If you're talking about free oxygen, then that might be an indicator for photosynthesis, but then it also might not.
Of course the Early Earth had little free oxygen, but did have life for a few hundred million years.

Why then would you equate oxygen with being "Earth-like"?

We have the Moon and Mars to play with. But we're years away from mastering those.
To send a manned mission to the nearest star would take between forty and a hundred thousand years, if they decided to spend the money right now. So it's of academic interest only at present.

There is a fundamental question that bothers many outside of academia, and that is whether life exists elsewhere.

What I don't get is why planets must be "Earth-like" for life to exist, but then I confuse easily on this subject.

[pErvinalia]

It's really not that confusing. What else are you going to look for? Earth is the only planet that we've discovered that contains life. So may as well look for planets with a similar natural history and astronomyey stuff.

[JimC]

Yes. This doesn't mean that life in very different environments is considered to be impossible, just that the default search environment is Earth-like.

[Brian Peacock]

Earth is the only reliable reference source we have.

[rainbow]

Earth is the only reliable reference source we have.

...which is exactly the problem. One is taking a single point and trying to extrapolate from there. All possible directions are equal.

For instance, if a person were to have lived in a village in Central Africa, they might well believe that everybody speaks Tumbuka. Clearly this is not the case.
Equally, if we assume all life forms are identical to us, we are likely to be mistaken. Not so?

[rainbow]

Yes. This doesn't mean that life in very different environments is considered to be impossible, just that the default search environment is Earth-like.

Circular reasoning. Life exists on Earth, therefore life, if it exists elsewhere must be identical to life on Earth. Therefore only planets like Earth will have life.