What are the odds that other life exists?

  • #1
Summary:: Like how is it possible that earth was just perfectly made for life?

It seems impossibly unlikely that earth would be able to harvest life. I also heard that the moon is exactly 400 times smaller than the sun and 400 times the distance from each other, which makes solar eclipses possible. How could a coincidence this major even happen? I also heard that the moon is getting farther and farther away from the sun, so eventually solar eclipes won't even be possible, so what are the odds that the only time sentiment beings are on earth, is the time solar eclipes happen. Like just how could that even happen?
 

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  • #2
russ_watters
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Summary:: Like how is it possible that earth was just perfectly made for life?

It seems impossibly unlikely that earth would be able to harvest life. I also heard that the moon is exactly 400 times smaller than the sun and 400 times the distance from each other, which makes solar eclipses possible. How could a coincidence this major even happen? I also heard that the moon is getting farther and farther away from the sun, so eventually solar eclipes won't even be possible, so what are the odds that the only time sentiment beings are on earth, is the time solar eclipes happen. Like just how could that even happen?
Life outside of Earth seems likely given the number of stars and planets out there, but the coincidence that gives us solar eclipses isn't really relevant to that. If anything it would be an argument for uniqueness (albeit a weak one) since it's a coincidence, which proves that coincidences happen.
 
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  • #3
Life outside of Earth seems likely given the number of stars and planets out there, but the coincidence that gives us solar eclipses isn't really relevant to that. If anything it would be an argument for uniqueness (albeit a weak one) since it's a coincidence, which proves that coincidences happen.
Isn't the uniqueness evidence of a creator?
 
  • #4
fresh_42
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Isn't the uniqueness be evidence of a creator?
No. Especially as the moon wasn't always and won't be always at this specific distance.
 
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  • #5
russ_watters
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Isn't the uniqueness evidence of a creator?
No. There's nothing about uniqueness that implies a creator. Flip a coin - regardless of whether it comes up heads or tails, that tells us nothing about whether there is a creator. Flip it again. Same. The more times you flip it, the more unique the sequence you get. All of that follows the laws of probability and has nothing to do with whether there's a creator.
 
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  • #6
hutchphd
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Earth harvested life that is perfect for earth. The probabilities are unfathomable as are the time periods involved.
If you cannot deal with unfathomable thoughts then make up whatever stories you wish, but please do not proselytize them here.
 
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  • #7
phinds
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Isn't the uniqueness evidence of a creator?
Nothing in science is evidence of a creator and this is a science forum, not a religious forum.
 
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  • #8
BillTre
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The modern NASA view of life possibly arising on other planets, is based on the presumed mechanism(s) of the origin of life on earth.
This is based on chemical interactions between water and the rocky material exposed on the surface of a new planet (like earth was about 4 billion years ago).
Water reacts with malfic and ultra malfic rocks (thought to be common on "rocky" planets I have read) in the serpentinization process to produce small carbon containing molecules in the presence of natural catalysts which in turn form larger organic molecules.

Sites on earth considered good possibilities for life to arise include alkaline hydrothermal vents. These vents are driven by flows of serpentinized water, and would have formed in early earth. They can still be found as the process continues today where new rocks are created due to sea floor spreading.

The rock and water situation may have occurred on Mars before it dried up, and may still exist on Enceladus, a big moon of Saturn.

Three possible sites in one solar system (one confirmed). Doesn't sound that unlikely.

This is the starting point of many scenarios for how life might have arose, and is considered not that unlikely a possibility when considering the vast numbers of planets, which @russ_watters mentioned.
 
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  • #9
phinds
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how is it possible that earth was just perfectly made for life?
Just to throw some number around:

There are approximately 10E12 galaxies in the observable universe alone and each galaxy has an average of 10E8 solar systems. Let's posit a single planet per solar system (likely a very low estimate). You then have 10E20 planets in the observable universe.

Assume that the odds of life forming on a planet are an outrageously low 1 in 100,000,000. That would mean that there is life on 1,000,000,000,000 planets in the observable universe. We just happen to be one of them.
 
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  • #10
russ_watters
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Assume that the odds of life forming on a planet are an outrageously low 1 in 100,000,000.... We just happen to be one of them.
Well...the odds of us being one of them are 100%.
 
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  • #11
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I also heard that the moon is getting farther and farther away from the sun, so eventually solar eclipes won't even be possible, so what are the odds that the only time sentiment beings are on earth, is the time solar eclipes happen.
Well the moon also has a solar eclipse and it will continue to have it long after the Earth will lose it. So an eclipse is not necessary nor sufficient for life.
 
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  • #12
DennisN
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What are the odds that other life exists?
Underneath my bathtub? Very likely.
It seems impossibly unlikely
Not under my bathtub.

Seriously, my feeling is that it is quite likely to exist elsewhere considering the ridiculous amount of stars (and probably exoplanets) in the observable Universe (and the rest of the Universe is likely even much bigger than the observable). But the probability of life in general (e.g. the ratio of planets with life), the nature of that life, the intelligence of it, the technology of it and so on I consider to be really big unknown issues which I think we are not even close to be able to estimate. We currently have only one data point, the Earth. Because of this I personally tend to get quite uneasy when I hear detailed speculations about extraterrestrial life. :smile:

Regarding our own neighborhood, I personally don't think life exists elsewhere in our Solar System, but it's more a feeling than scientific reasoning, and I could very well be wrong.

Just my two cents.
 
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  • #13
PeroK
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Just to throw some number around:

There are approximately 10E12 galaxies in the observable universe alone and each galaxy has an average of 10E8 solar systems. Let's posit a single planet per solar system (likely a very low estimate). You then have 10E20 planets in the observable universe.

Assume that the odds of life forming on a planet are an outrageously low 1 in 100,000,000. That would mean that there is life on 1,000,000,000,000 planets in the observable universe. We just happen to be one of them.
There's no data to justify that estimate of 1 in 100,000,000. That's just a number picked out of the air.

Until there is some evidence of how likely it is for life to emerge from organic compounds (abiogenesis), then any argument on statistical grounds does not hold up.

The honest answer is that we do not know. We might have a gut feeling that what happened on Earth was not particularly improbable, but there is no statistical data to back that up.

One possible statistical argument involves the multiverse anthropic principle. If we imagine many universes where some have laws of physics that allow life to flourish, some where it's probable for life to emerge in only a few places and most have laws of physics that make life impossible, then there's a potentially valid argument based on conditional probablity: given life on Earth it's highly probable that we life in a universe with an abundance of life.

Strictly speaking, however, there is no data to say that laws of physics ever allow life to be abundant. In other words, if we postulate that our universe has the optimum possible conditions for life, and yet it's still very rare (i.e. we might be alone), then even this statistical argument fails. And, clearly, we don't know how likely it is that there is a multiverse of independent universes, each with its own laws of physics.
 
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  • #14
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Just to throw some number around:

There are approximately 10E12 galaxies in the observable universe alone and each galaxy has an average of 10E8 solar systems. Let's posit a single planet per solar system (likely a very low estimate). You then have 10E20 planets in the observable universe.

Assume that the odds of life forming on a planet are an outrageously low 1 in 100,000,000. That would mean that there is life on 1,000,000,000,000 planets in the observable universe. We just happen to be one of them.
And it's quite possible that the "entire" universe is infinite... So there is that.
 
  • #15
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There's no data to justify that estimate of 1 in 100,000,000. That's just a number picked out of the air.

Until there is some evidence of how likely it is for life to emerge from organic compounds (abiogenesis), then any argument on statistical grounds does not hold up.

The honest answer is that we do not know. We might have a gut feeling that what happened on Earth was not particularly improbable, but there is no statistical data to back that up.

One possible statistical argument involves the multiverse anthropic principle. If we imagine many universes where some have laws of physics that allow life to flourish, some where it's probable for life to emerge in only a few places and most have laws of physics that make life impossible, then there's a potentially valid argument based on conditional probablity: given life on Earth it's highly probable that we life in a universe with an abundance of life.

Strictly speaking, however, there is no data to say that laws of physics ever allow life to be abundant. In other words, if we postulate that our universe has the optimum possible conditions for life, and yet it's still very rare (i.e. we might be alone), then even this statistical argument fails. And, clearly, we don't know how likely it is that there is a multiverse of independent universes, each with its own laws of physics.
We have a sample size of one 😟
 
  • #16
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If life emergence is the result of a natural and random process, then there is a very high probability that life exist in many places in the universe where the conditions are favorable.

Let p be the probability that life emerges spontaneously due to a natural and random evolution process at some point and time in the universe. The probability is likely extremely small. The probability that it doesn't emerge is 1-p. The probability that it never emerges in a given volume v and time duration t is then (1-p)^vt. Even when p is extremely small, this probability tend to zero when v and t are huge.

Thus, if the conditions are favorable and life emergence is due to a natural and random process, there is a high probability that life will emerge because the probability that it doesn't emerge tends to zero.

Note that this reasoning is valid as long as the hypothesis that life emergence result from a natural and random process is valid. It is the mainstream assumption of scientists based on empirical evidences.

The mainstream assumption of various religious beliefs is that life is the product of a creation. In this case it might well be plausible that we are alone in the universe.

As long as there is uncertainty on the validity of the hypothesis, reasonable doubt is permitted on the existence of extraterrestrial life instances. Space exploration with the goal to find out extraterrestrial life is thus very important to understand our status in the universe.

PS: the probabilistic argument is from Dr De Duve in his book "Singularities: Landmarks on the Pathways of Life".
 
  • #17
fresh_42
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I am not so optimistic considering the probability argument about high numbers. If we list everything that had to fit so that earth could develop life (us), then we get a rather long list of specific circumstances distributed over the entire lifecycle of our planetary system, the combination of the different sizes of its planets, its position within the galaxy, the absence of near gamma-ray sources, the stability of earth's magnetic field, the moon, the amount of water, the extinction of predecessor populations, etc. It would be more convincing if we can find e.g. bacteria on Europe.

However, this has still nothing to do with evidence for a creator. Chances to win the lottery are almost zero. Yet there are people who win. This can hardly be interpreted as divine interference.
 
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  • #18
gmax137
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I also heard that the moon is exactly 400 times smaller than the sun and 400 times the distance from each other, which makes solar eclipses possible. How could a coincidence this major even happen?
Brings to mind:

Feynman said:
You know, the most amazing thing happened to me tonight. I was coming here, on the way to the lecture, and I came in through the parking lot. And you won’t believe what happened. I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!
 
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  • #19
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Potential explanations for uniqueness are numerous. You could have "there exists a creator" among them, but there is no reason to prefer this option over another, especially when another explanation is a more satisfactory one.

On a more cynical note, "there exists a creator" is more like an appeal to ignorance if that is your first option at explaining some odd phenomenon You don't know how to explain (rationally).
 
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  • #20
hutchphd
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I note that "a creator" is a one sizefits all solution to all problems and quote the Deteriorata (National Lampoon)


You are a fluke of the Universe.
You have no right to be here, and whether you can hear it or not,
The Universe is laughing behind your back.
Therefore make peace with your God whatever you conceive him to be,
Hairy Thunderer or Cosmic Muffin.
With all its hopes, dreams, promises, and urban renewal,
The world continues to deteriorate.
Give up.



.
 
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  • #21
hutchphd
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While I'm quoting howabout the late Steven Weinberg:
Weinberg told a New York Times interviewer in 1999, “With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.”

.
 
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  • #22
russ_watters
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We have a sample size of one 😟
That only tells us that the odds aren't zero.

I predict that in my lifetime/the next 50 years scientists will have a much better idea of the odds, either finding or mostly ruling out life elsewhere in the solar system or nearby star systems.
 
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  • #23
I predict that in my lifetime/the next 50 years scientists will have a much better idea of the odds, either finding or mostly ruling out life elsewhere in the solar system or nearby star systems.





I think these two video's are a fun watch!
 
  • #24
TeethWhitener
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It would be more convincing if we can find e.g. bacteria on Europe.
I’ve been to Europe; it’s not that nice.
 
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  • #25
fresh_42
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I’ve been to Europe; it’s not that nice.
Then you've been in the wrong places. It is nice.
 
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