91–100 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?
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…
Never heard of the "people don't actually read it" meme.
That’s a beautiful article showcasing our predicament in having access to more information about the universe. Now i have to be the one to ask the dumb defensive question: what makes us so certain that we can trust what we see on James Webb? Can we definitely discard a measurement problem?
If you're worried about bad pixels or noise, it seems like there is an easy fix: point it in a direction specified by some angles theta & phi, wait long enough to accumulate light from distant faint objects (high redshift galaxies etc), then shift Webb's orientation by a small amount to theta+delta_1 & phi+delta_2, which will have a significant overlap with the original image, and after taking the 2nd image check to…
Earlier quoted context omitted.
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?
I'm not sure anything after the event horizon right? Since no light == no information.
As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories. What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know. I imagine that various…
The evidence for the big bang is generally not that if you look far enough back in a telescope, the universe looks younger, which is somewhat the layperson's confusion. Evidence for the big bang is about measuring redshift of galaxies throughout universal history, homgeneity and thermal equilibrium of the universe and CMBR, which could only be explained by it all having been in a compressed location where it could re…
This led to the development of cosmic inflation [2], which is what largely drove me from a doe eyed young astronomy enthusiast to a highly skeptical old fart. It solves the problem in an ad hoc fashion. Just have the universal expansion go into overdrive for a bit shortly after the big bang, then slow down, then start accelerating again - and then at the end we finally get something that looks like what we see - a homogeneous system in this case.
It made some highly accurate and improbable predictions which led to widespread adoption but then ran into numerous issues requiring further ad-hoc solutions. And this process has been repeated multiple times since its original formulation, to the point that there's a library of different inflation theories now a days, all getting ever more fine-tuned. If non-casually connected regions of space acted like they were non-casually connected then all would be fine, but the homogeneity that we do have is a big problem for the big bang.
It turns out that brown dwarfs are actually corrected for, so my remembrance is correct but factored in. I’m posting anyway because 1) it’s interesting and mildly relevant and 2) others might have the same “vague but unclear” recollection I had and appreciate the elaboration.
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 book assumes a basic knowledge of physics and cosmology so it does not spend half the book reviewing basics like many pop physics books do.
[1] https://press.uchicago.edu/ucp/books/book/chicago/B/bo244963...
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…
Maybe godel, escher, bach would be a better "book that people talked about but never read"
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…
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?
Anything smaller while also lasting long enough to do an experiment on and you'd likely end up producing too much energy and destroying the planet.