I Successful predictions from anthropics? (History of science question)

[windy miller]

Earth's distance from the sun is said to lie in a small Habitable Zone (HZ) . How did it come to be in such a fortunate position? It seems that someone in the past could have asked this question and concluded on the basis of anthropics there must be a large number of planets in our galaxy. My question, did anyone actually make this prediction on that basis ? If so who and how old does the argument go back? I know Bruno speculated on other worlds and even the ancient atomists in Greece did but I doubt it was due to the HZ as that wasn't know at the time. Which brings to another question , how old is knowledge of the HZ?
Any help most welcome , thanks.

 

[anorlunda]

Earth's distance from the sun is said to lie in a small Habitable Zone (HZ) . How did it come to be in such a fortunate position?

Another way of saying HZ is that the planets in the zone are more likely to spawn life. There may be several planets in the zone of a planetary system.

Think of a dart board. Throw 100 darts at it. Suppose one of the darts is in the bullseye, and you ask, "What is special about that dart that made it so fortunate?"

 

[windy miller]

Another way of saying HZ is that the planets in the zone are more likely to spawn life. There may be several planets in the zone of a planetary system.

Think of a dart board. Throw 100 darts at it. Suppose one of the darts is in the bullseye, and you ask, "What is special about that dart that made it so fortunate?"

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Thanks for taking the time to respond but my post was not really trying to have the concept of the HZ explained but rather to try and get some history . So the questions are
1. did anyone predict the existence of exoplanets based on athropics or not
2 if they did when did they?
3 when was the concept of the HZ first understood?

 

[HomesliceMMA]

Thanks for taking the time to respond but my post was not really trying to have the concept of the HZ explained but rather to try and get some history . So the questions are
1. did anyone predict the existence of exoplanets based on athropics or not
2 if they did when did they?
3 when was the concept of the HZ first understood?

windy, I dunno, but in case its any help (and it probably won't be lol), my thoughts:

1. I don't think so. The anthropic principle is something along the lines of: "the fact that we are here on a habitable planet should not be surprising, as if we could never arise on a non-habitable planet." So the anthropic principle I would guess does NOT indicate there should be additional planets. Not that it is inconsistent with them, however.

2. N/A given #1.

3. Do not know, but I highly suspect many, many years ago. https://en.wikipedia.org/wiki/Fermi_paradox This shows up in the 1950s, probably even the 1930s, so at least that far I would think. But probably very long before that.

Happy to not help lol!

 

[haushofer]

Giordano Bruno predicted the existence of other solar systems, but on the omnipotence of god.

I'm not aware of any anthropic predictions besides Weinberg's paper on the cosm.constant. See also my topic

https://www.physicsforums.com/threa...-tuning-to-a-multiverse.1048203/#post-6832800

about the validity of your inference.

 

[PAllen]

By the anthropic principle, I argue that the existence of homo sapiens is possible.

 

[Haelfix]

A lot of anthropic predictions are posthoc. For instance, the value of the fine structure constant has to lie within a certain range for life and chemistry to be possible.

I am not aware of many examples where this was inverted to make a prediction. The only (kinda/sorta) exception that I know of, other than Weinbergs CC observation was Fred Hoyles prediction about a new resonant state of carbon12 in stars (called the Hoyle state)..

It should be noted that a lot of the anthropic principle stuff borders on tautology, so its always somewhat definition/philosophy dependent.

 

[haushofer]

A lot of anthropic predictions are posthoc. For instance, the value of the fine structure constant has to lie within a certain range for life and chemistry to be possible.

I am not aware of many examples where this was inverted to make a prediction. The only (kinda/sorta) exception that I know of, other than Weinbergs CC observation was Fred Hoyles prediction about a new resonant state of carbon12 in stars (called the Hoyle state)..

It should be noted that a lot of the anthropic principle stuff borders on tautology, so its always somewhat definition/philosophy dependent.

I think the anthropic reasoning is important if you want to reformulate scientific hypotheses into Bayesian form, because anthropic reasoning introduces an observer bias. This has implications for the way you sample your own existence, but there is no agreement how to sample exactly. See e.g. Nick Bostrom's book on anthropic bias:

https://anthropic-principle.com/

 

[Maarten Havinga]

By the anthropic principle, I argue that the existence of homo sapiens is possible.

How much probability do you attribute to homo sapiens not existing (the falsification of this reasoning with the anthropic principle), a priori? Just how unexpected is this "prediction" that hey, it turns out homo sapiens exists? What progress does this give to modern science?

 

[KobiashiBooBoo]

I'm beginning to think it's just us out there (here).

 

[pinball1970]

I'm beginning to think it's just us out there (here).

One of Webb's area of study is looking at exo planets in more detail than before, identifying chemical signals that possible indicators for life. Worth keeping in touch with those releases as they become available. Example here. https://exoplanets.nasa.gov/news/17...an-exoplanet-atmosphere-as-never-seen-before/

 

[KobiashiBooBoo]

Another way of saying HZ is that the planets in the zone are more likely to spawn life. There may be several planets in the zone of a planetary system.

Think of a dart board. Throw 100 darts at it. Suppose one of the darts is in the bullseye, and you ask, "What is special about that dart that made it so fortunate?"

View attachment 318557

The dart in the bullseye says "There should be more darts in bullseyes, how else did we end up here? It must have been quite likely."