Probabilities of earth like orbits, and solar systems like ours?

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Discussion Overview

The discussion revolves around the probabilities of Earth-like orbits and solar systems similar to ours. Participants explore the definitions and criteria that might characterize such orbits and systems, as well as the implications of these probabilities in the context of the universe's vastness and the potential for life.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the probabilities of Earth-like orbits and solar systems are near nonexistent in the known universe, but acknowledge the vast unknowns that make definitive answers speculative.
  • There is a contention about what constitutes an Earth-like orbit, with questions raised regarding the shape of the orbit, distance from the star, and the star's luminosity.
  • Participants debate the criteria for a solar system to be considered like ours, including the type of primary star, the presence of planets, and the diversity of those planets.
  • One participant proposes rephrasing the question to focus on the permutations of orbits and solar system dynamics, questioning the relevance of the Anthropic Principle (AP) in an infinite universe.
  • Another participant expresses skepticism about the fine-tuning of our solar system for life, raising questions about the necessity of gas giants in protecting inner planets from debris.
  • There is uncertainty about the essential ingredients required for a life-supporting system and whether our existence would be possible without certain planetary bodies like Jupiter or Saturn.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of Earth-like orbits and solar systems, with no consensus reached on the probabilities or the relevance of the Anthropic Principle. The discussion remains unresolved regarding the necessary conditions for life and the uniqueness of our solar system.

Contextual Notes

Participants highlight limitations in defining key terms such as "Earth-like orbit" and "solar system like ours," which affects the clarity of the discussion. There is also an acknowledgment of the speculative nature of the topic given the vastness of the universe.

wolram
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What are the probabilities of Earth like orbits, and solar systems like ours?
 
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near nonexistant in the known universe...however there is so much out there that we cannot even begin to know or see, it's all simply speculation when answering a question like this.
 
The question is too ill defined to have an answer. What defines an Earth-like orbit? That is is circular? That it is in a given range of AUs from its star? That the apparently luminosity of its star tends to be similar (within a certain range)?

Likewise, what constitutes a solar system like ours? That it has a non-binary primary star? That it is orbited by planets? That those planets include both inner rocky planets and outer gas giants?

I presume that the underlying question is something along the line of "how many systems can support life as we know it" and that this is a subquestion in that line of reasoning.
 
Ohwilleke
If you like i will try to rephrase the question , given that there is only so
many permutations for orbits, solar system dynamics, what is the probability
of the AP being correct
 
wolram said:
Ohwilleke
If you like i will try to rephrase the question , given that there is only so
many permutations for orbits, solar system dynamics, what is the probability
of the AP being correct
I believe that the universe is infinite both temporally and spacially, although I cannot prove either. If the U is truly infinite, the AP is absolutely irrelevant. Post 17 in this thread sums up my disgust with this concept:

https://www.physicsforums.com/showthread.php?p=532639#post532639

If every living being (even ones that we would not consider sentient) in the present universe is entitled to claim that the Universe was fine-tuned to produce them personally or as a species, we are in pretty big trouble. Some string theorists seem enamoured of this concept. Why not? There are almost as many string theories as there are string theorists, yet none of them make solid falsifiable predictions about our Universe. Draping the Anthropic Principle over these theories may provide some hope that String (M theory) is not quite dead, but how many decades can you spend developing a theory before the funding entities ask you to make a testable prediction or two?
 
Turbo-1
I can not disagree with any of your post, but i was wondering how finely
tuned "our" solar system needs to be to support life, Earth's distance from
the sun and its circular orbit is one factor, but what if we did not have
a gas giant to intercept spaces debris, etc etc.

If our U is infinite then the possibility is that our solar systems format is not
unique," it is just a matter of probabilities".

The thing i am not sure about is the ingredients needed to make a sustained
life supporting system, ie would we be here if saturn did not exist or jupiter?
 

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