Comfort zone

It is frightening to me that I cannot comprehend how the universe started, how far are its parameters, why we “live” for such a short interval when there is so much to learn and enjoy. But to those who are great believers in God, they are fearless because they “know where they are going” and who constructed the universe etc.

Interesting, if old, observation. Mayhaps you have something you’d like people to debate, or does this belong in MPSIMS?

Okay, I’ll bring up something to debate. And it even fits with the topic of this thread.

How wide is the “comfort zone” around the Sun, in which the Earth (or an Earth-like planet) could support life? And how close are we to either edge of this zone?

“Love 'em, fear 'em, and leave 'em alone.” – Dr. Spockiavelli

What in the name of Webster’s Dictionary are you talking about?

How does having faith make one “fearless?”

The most fundamental religious folks I’ve seen are, on the whole, the most scared and insecure people I’ve ever met.

Yer pal,

Just remember, “scared” is only one letter-transposition away from “sacred”.

No, NO, not transpositions! Then we’d have to turn ‘Yer pal, Satan’ into ‘Yer pal, Santa’, or ‘Stan, a player’ (if we’re not particular about case), and tracer would turn into a crater.

I’m biased, of course, but I’d say there’s something to the notion. Freud commented about the tendency of people to be more confident if they know they’re loved. If it happens to be God’s eye that you feel you’re the apple of, then yes, that can help you feel pretty fearless.

I made a God’s eye in elementary school once. But the yarn came unwound.

tracer asks:

Meaningless question on two counts:
[list=1][li]You haven’t specified the greenhouse constituents of the atmosphere. The blackbody temperature of the Earth is, IIRC, about -15°C, same as of Luna. Moreover, sagans of years ago, when the Sun was much less luminous, the temperature of the Earth was still much the same, due to a different atmospheric composition.[/li][li]More speculatively, there’s no good proof that Earthlike conditions are required for life. A different biochemistry will seem “natural” to such intelligent beings as might have it, regardless of how unusual it might be on a universal scale.[/list=1][/li]

“Kings die, and leave their crowns to their sons. Shmuel HaKatan took all the treasures in the world, and went away.”

Interesting question, tracer. I’ve often suspected that if the positions of Venus and Mars were reversed, each would display Earth-like temperatures. The atmospheric pressures would still be vastly different.

The Earth’s climate would be radically different if it were to change orbits only slightly, but that doesn’t mean life couldn’t be supported at other distances from the sun. So it’s hard to say what the life-giving band is. Some of our best shots for live-sustaining stuff in our solar system aren’t very close by; one of the favorites is Titan, a moon of Saturn, which has a pretty substantial atmosphere. Naturally it would be pretty chilly way out there, but there could very well be geothermal vents heating the surface from inside.

Anyway, next time I’m on Titan I’m gonna look really hard for signs of life…

Um, Akatsukami, those two counts are some of the factors that need to be taken into account to answer the question. That hardly makes it “meaningless”.

No, I contend otherwise, tracer. Unless it is considered implicit to the question that it is meant:
[list=1][li]The planet is exactly like Earth, including the atmospheric composition;[/li][li]The biochemistry and biology are exactly like Earth’s; and[/li][li]There is no homeostatic mechanism functioning between that planet and those lifeforms (i.e., we throw out the Gaia hypothesis)[/list=1][/li]those things have to be specified first.

Boris B asked what the temperature of a Venus-like world in a Martian orbit would be. Very simple: it would have to be the same as Venus’s temperature is now; this because the temperature (and insolation, and other things) have made Venus what it is today. Otherwise, we have to start by explaining why that world has an atmosphere with a partial pressure of CO[sub]2[/sub] about a quarter of million times that of Earth.

“Kings die, and leave their crowns to their sons. Shmuel HaKatan took all the treasures in the world, and went away.”

What you mean, Atso, is not that the question is meaningless, but that it is too broad to be easily answered. It’s not meaninglyss, it just leaves too many variables.

Er, not atso, Akatsukami. What was I thinking?

Hey, look, it’s snowing!!

Well, Surgoshan, to my mind, it’s rather like asking: “How long is a piece of string?”. I suppose that we can specify which piece of string, and give content to the question, but until we do, we might as well answer, “About a duck”, and note that that communicates as much (and as little) information as any other phrase.
Now, assuming that everything else is equal (which, of course, it never is), we can get the answer by applying the inverse square law and the Stefan-Boltzmann law. Inverse square tells us that at half the distance, insolation will be x[sup]-2[/sup] or four times as great. S-B tells us that, if the insolation (or other incoming radiation) is four times as great, the blackbody temperature will be T[sup]1/4[/sup], or approximately 41% higher (planets aren’t blackbodies, but they’re reasonable approximations).
But then, as I said, the first question in my mind would be, “OK, why isn’t the geochemistry, etc, of the planet appropriate to a planet that much hotter (or colder)?” After all, if Venus was in Mars’s orbit, all of that CO[sub]2[/sub] wouldn’t be free in the atmosphere, it would be tied up in the regolith.

“Kings die, and leave their crowns to their sons. Shmuel HaKatan took all the treasures in the world, and went away.”