101–110 of 141 posts
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
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There was never a time when a book gave the public an overview of the universe. ABHOT was so popular for being a book no one actually read, theres even an index named after Hawking due to it: https://en.wikipedia.org/wiki/Hawking_Index Did _you_ read that book? There however definitely was a piece of media that captured public minds and educated them about the cosmos. And that was the show Cosmos. The original of cou…
I knew dozens of people in my high school who actually read it. Maybe godel, escher, bach would be a better "book that people talked about but never read"
Fun fact: The very first book ever sold on Amazon was "Fluid Concepts And Creative Analogies: Computer Models Of The Fundamental Mechanisms Of Thought" also by Douglas Hofstadter
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Of course if we had a black hole in a lab (or one in a convenient orbit) we could run all sort of experiments, but which experiments exactly? We will start by throwing things at it and watch, obviously, but that's unimaginative. What are the smart experiments?
If you had a small black hole in a lab you could generate power from the hawking radiation, likely enough to power the entire world. A 1,000,000 ton black hole would last over a thousand years without feeding it more mass and produce about 300 TW of energy (increasing over time, so you better keep feeding it). You'd also need some pretty good sunglasses to be able to watch things being thrown into it. Also I'm not su…
And can you charge the hole with enough of a charge to use electromagnetism to move and contain it?
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
The very useful Open Syllabus Project collects syllabi and lists the most popular books, etc.: https://www.opensyllabus.org/
A professor's course materials may suit your need.
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
Earlier quoted context omitted.
I took a good long look at the CMB picture, including the caption. It basically says the Universe was one big hot apparently uniform ball at one stage. I don't know what conditions were like before that stage, but like Eric Idle says, nothing can come from nothing. Dark energy is a horse shit name for a theory that was horse shit to begin with. The Universe is probably just inhomogeneous, like your intuition is sayin…
Why do you say "probably"? We can measure and quantify the inhomogeneities very precisely, and they're tiny. This isn't a matter of opinion or intuition.
I thought I read somewhere that many of these little red dots are turning out to be nothing more than bog-standard brown dwarfs in our own galaxy that are confusing the signal. These days we have some pretty powerful agents who can read these things faster than I can, so I went and found the paper: https://arxiv.org/abs/2506.04004 It turns out that brown dwarfs are actually corrected for, so my remembrance is correct…
Your own paper estimates 5 to 25% may be brown dwarfs, and says nothing about whether they might be in our galaxy or not.
The most exciting idea to me that JWST has bolstered is primordial black holes. Many models already predict them but JWST has provided the first good indirect evidence in the form of too-early galaxies. The models that predict PBHs predict that. If they exist, they would not be constrained to stellar mass and above. There could be a population of little black holes floating around. Anything under the mass of a decent…
How certain is the evaporation? Obviously Hawking radiation has never been observed, but is it tied in enough to other known physics that we can be reasonably certain it exists?
If it doesn't exist its also has profound implications for the long term fate of the universe, since it would mean black holes never evaporate.
Earlier quoted context omitted.
If you had a small black hole in a lab you could generate power from the hawking radiation, likely enough to power the entire world. A 1,000,000 ton black hole would last over a thousand years without feeding it more mass and produce about 300 TW of energy (increasing over time, so you better keep feeding it). You'd also need some pretty good sunglasses to be able to watch things being thrown into it. Also I'm not su…
So the hawking radiation is so strong that it impedes matter falling into the hole? And can you charge the hole with enough of a charge to use electromagnetism to move and contain it?
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
There was never a time when a book gave the public an overview of the universe. ABHOT was so popular for being a book no one actually read, theres even an index named after Hawking due to it: https://en.wikipedia.org/wiki/Hawking_Index Did _you_ read that book? There however definitely was a piece of media that captured public minds and educated them about the cosmos. And that was the show Cosmos. The original of cou…