Formation of the Moon

exchemist said:
I’ve learnt quite a few things over the years from these forums.

Interestingly, some of the most memorable have been from cranks, quoting from people I had not known much about, or had not known of at all. For instance there was a climate change denier, on another forum, who introduced me to the work of a c.19th Irishman called Tyndall. Tyndall had invented what was in effect the world’s first infra red spectrometer! I had no idea about this man’s work. It was really clever for the Victorian era. And this Tom Booth guy made me read up some of Sadi Carnot’s writing about the nature of heat, which I had never looked at before. Booth also came up with an ingenious, if naturally futile, attempt to get round the 2nd Law of Thermodynamics by means of an “ice engine”. This turned to have a lot in common with the early “atmospheric” steam engines, but it took me long walk in the park to work out that it was really the same principle. So good fun all round,
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Ok time to play my dumbass card of the day..... i thought u meant some sort of frozen water engine......

I see now its a standard internal combustion engine...... i am a wee bitty embarrassed.....

what a tool i am indeedy.

Das ist nicht einmal falsch indeed.
 
Fermer05 said:
Formation of the Moon.
https://astrotalk.ru/viewtopic.php?f=5&t=10510
8. The bulk of the Solar System's mass is concentrated in the Sun and the ecliptic plane; due to this, asteroids and meteoroids orbiting the Sun slowly draw closer to both the Sun and the ecliptic plane, resulting in the formation of the Kuiper belt.
Next, icy planets emerge from the Kuiper belt, surrounded by atmospheres and ring systems from which satellites later form.
After the Moon formed from Earth's rings, a significant number of asteroids continued to orbit Earth; by crashing into the Moon's cooling surface—which had a thin, soft crust—they created flat-bottomed craters.
It is possible that, due to the Moon's weak gravity and soft surface, the first asteroids left behind long sprays of magma. https://science.nasa.gov/moon/formation/#h-searching-for-the-past-in-the-future
It is believed that the Moon originated by chance—either as a result of a celestial body colliding with the young Earth or by being accidentally captured by Earth's gravitational field while passing by.
At the same time, there is no such thing as chance in nature; everything within it is predetermined. Why, then, did Earth not—by chance—capture a second or third moon?
Many planets possess satellites and other attributes, and these did not come into existence by chance.

Continued at: Astronomy and Microscopy Forum. https://forum.shvedun.ru/viewtopic.php?f=14&t=7503
"Na Flagmane" Forum. https://vmf.net.ru/forums/viewtopic.php?t=2328
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The topic of this thread is "The Formation of the Moon"; please try not to stray too far from the stated subject.
 
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Pyab said:
Always like to learn though i do worry about being an old dog these days...........

I did see mention of the ice engine, think ill make that my wee task for today...of course I'm at work, so officially, i wont.
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To explore that you would need to visit a different science forum, where Tom Booth posted about it. Forum etiquette forbids me from directing you to a rival site.

But the principle was to use the 8% expansion of water on freezing to lift a weight. There would be ratchet to stop the weight falling back, so that by successive filling of a cylinder with water, freezing it to push up the weight, then thawing it and admitting more water before freezing it again, and so on, it would lift the weight higher and higher, thereby doing mechanical work against gravity.

The seeming paradox, which Tom wrongly thought defeated the laws of thermodynamics, is that heat is extracted (i.e. to make the water freeze) on the power stroke, when the mechanical work is done. He thought in a heat engine one has to put heat in on the power stroke so that (some of) it can be converted to work.

But in fact Newcomen's early steam engines also had this feature. A cylinder was filled with steam at atmospheric pressure and then cold water was sprayed in, which rapidly condensed the steam, causing a partial vacuum which drew the piston in (in fact pushed in by the external ambient atmospheric pressure.) This is why they are called "atmospheric engines". The early steam boilers were cast iron which is brittle and cannot withstand a high steam pressure, so it was not possible to inject high pressure steam and get steam expansion to do the work, as in a modern steam engine (like that in P.S. Waverley or a steam locomotive).

But in either an atmospheric steam engine or Tom's ice engine, over a complete engine cycle heat is supplied, a proportion is converted to work and the balance is rejected as waste heat. So the 2nd Law applies perfectly well. Tom had just got himself in a muddle over it.
 
Pyab said:
Ok time to play my dumbass card of the day..... i thought u meant some sort of frozen water engine......

I see now its a standard internal combustion engine...... i am a wee bitty embarrassed.....

what a tool i am indeedy.

Das ist nicht einmal falsch indeed.
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No, no it absolutely was a frozen water engine. See my previous post explaining it. :)

But it's true that we are way off topic now, so we'd better stop this side discussion.
 
exchemist said:
No, no it absolutely was a frozen water engine. See my previous post explaining it. :)

But it's true that we are way off topic now, so we'd better stop this side discussion.
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oh is that not allowed? i didn't know..whaurs the rules?
 
exchemist said:
That story comes from Ringworld. Slaver sunflowers.
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Yes that was Ringworld I was referring to, not a spin-off. I enjoy the way Niven's Known Space stories include things like Slaver tech left over from the distant past. The Pak Protector genetic legacy was another one, with humans still capable of making the transformation when exposed to the Tree of Life. And the Ringworld, in later novels, turns out to have been built by Pak Protectors. What was her name - Teela? - becomes a Protector stage human in RW Engineers.
 
Pyab said:
oh is that not allowed? i didn't know..whaurs the rules?
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A bit non-intuitively, they are to be found in Site Feedback. Here they are: https://www.sciforums.com/threads/sciforums-site-rules.

But it obviously makes sense not to derail a thread by inserting an unrelated subject, while there still may be others who want to pursue the original thread topic. What one should do, if an interesting sidetrack develops, is to start a new thread with that as its subject. Sometimes, though, the thread gradually morphs from one topic to another by mutual consent. That seems to be acceptable.
 
TheVat said:
Yes that was Ringworld I was referring to, not a spin-off. I enjoy the way Niven's Known Space stories include things like Slaver tech left over from the distant past. The Pak Protector genetic legacy was another one, with humans still capable of making the transformation when exposed to the Tree of Life. And the Ringworld, in later novels, turns out to have been built by Pak Protectors. What was her name - Teela? - becomes a Protector stage human in RW Engineers.
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Ah. I only read Ringworld itself. I enjoyed the ideas but was a bit put off by what seemed to be a tendency to diminish the female sex. Non-sentient females seemed to crop up disturbingly often, whereas in real, terrestrial biology it is usually the male that is the expendable variant.

But now we are off-topic again..,,,
 
exchemist said:
Ah. I only read Ringworld itself. I enjoyed the ideas but was a bit put off by what seemed to be a tendency to diminish the female sex. Non-sentient females seemed to crop up disturbingly often, whereas in real, terrestrial biology it is usually the male that is the expendable variant.
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That's a staple of most science fiction of that era, from Heinlein (not _that_ bad) to John Norman (as bad as it gets.)
 
Pyab said:
error 404 on the rules...

i agree. sticking to topic is good
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Sciforums site rules

Sciforums - Rules, posting guidelines and advice to members (summary) Sciforums is an intelligent community that encourages learning and thoughtful discussion. We expect and welcome contributions that inform as well as stimulate discussion and debate. At its foundation, sciforums focused on...
www.sciforums.com www.sciforums.com

It's a tricky subject. As you can see, some posts are way off-topic. In a thread like this, it's kind of pointless to try to stay on-topic. You can see that the OP himself is all over the place. He makes noises about science-y stuff and then he's off about "it's all an illusion don't believe what you see", so trying to "stay on-topic" is largely meaningless.
 
exchemist said:
Ah. I only read Ringworld itself. I enjoyed the ideas but was a bit put off by what seemed to be a tendency to diminish the female sex. Non-sentient females seemed to crop up disturbingly often, whereas in real, terrestrial biology it is usually the male that is the expendable variant.
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billvon said:
That's a staple of most science fiction of that era...
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In Niven's case though, it was deliberate - he did it to highlight female humans as the equals of male humans. (With the exception of Teela, generally his female human characters were as capable as any man.)

Kzinti and other races often underestimated female humans, to their peril. Something some readers might learn a thing or two from.

That was the intent.
 
DaveC426913 said:
In Niven's case though, it was deliberate - he did it to highlight female humans as the equals of male humans. (With the exception of Teela, generally his female human characters were as capable as any man.)
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Every science fiction author is a product of their time. What was feminist 50 years ago is, today, a little cringe. Yes, Niven made an effort - but overall he was pretty sexist, which was likely just society at the time bleeding over into his writing, rather than him being a misogynist or anything. I remember one scene from one of "the long arm of Gil Hamilton" stories where a woman was found guilty of murder, sentenced to death, and her legs used as donor legs for someone else. Hamilton proves her innocent and gets her exonerated, so they find some (not quite matching) legs to graft onto her so she could be released.

Niven had a statement along the lines of "her perfection was ruined. No man would ever look at her the same again." Nothing about how it felt to her.

If you want to compare him to a writer of that era, compare him to Joe Haldeman, which I think did an excellent job of having actually equal female characters. (I'm a bit biased of course but he's a good comparison.)
 
billvon said:
That's a staple of most science fiction of that era, from Heinlein (not _that_ bad) to John Norman (as bad as it gets.)
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billvon said:
Every science fiction author is a product of their time. What was feminist 50 years ago is, today, a little cringe. Yes, Niven made an effort - but overall he was pretty sexist, which was likely just society at the time bleeding over into his writing, rather than him being a misogynist or anything.
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Or his readership is.

billvon said:
I remember one scene from one of "the long arm of Gil Hamilton" stories where a woman was found guilty of murder, sentenced to death, and her legs used as donor legs for someone else. Hamilton proves her innocent and gets her exonerated, so they find some (not quite matching) legs to graft onto her so she could be released.

Niven had a statement along the lines of "her perfection was ruined. No man would ever look at her the same again." Nothing about how it felt to her.
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The Patchwork Girl, I think.

billvon said:
If you want to compare him to a writer of that era, compare him to Joe Haldeman, which I think did an excellent job of having actually equal female characters. (I'm a bit biased of course but he's a good comparison.)
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The Forever War. One of the classics. And im not a military sci-fi fan.
 
Fermer05 said:
View attachment 7750
Stars are huge, glowing spheres that move extremely slowly around the Sun and from which asteroids subsequently form.
As they approach the Sun, the orbital speed of the stars increases. If every star were a Sun, the stars would move much faster.
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I assume the star and the asteroids have the same mass, and the radius of the solar system is about one trillion kilometers.
 
James R said:
There's no cycle that returns light to the sun.
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Seas and oceans will dry up when the rain stops falling, and the rain will stop falling when the seas and oceans dry up. And the Sun will go out when planets and satellites stop falling into the Sun.
 
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