Astronomy and Cosmology

Hello, When I think about the expansion of the universe, and how it appears to be accelerating, I understand that the expansion of the universe is more than just galaxies moving apart at greater and greater speeds but space itself expanding at an accelerated rate. But if space is expanding at an accelerated rate, does that mean time is also expanding at an accelerated rate? Or speeding up? Space and time are, after all, part of one continuum called "spacetime", are they not? If so, what does that entail?

The new telescope is stirring up a lot of controversy, we are seeing objects at distances that defy logic. The truth of the beginning will never be known unless we can detect the very last and most distant galaxies out there. Will we ever have an instrument that can detect the true edge of the universe? More and more theories are coming to light regarding the time of the beginning and the course. We live in a new age but we always have and if we always do we may never find the answers we are searching for.

The FLRW metric is often described using the symbol \(\chi\). It occurred to me that many of our viewers would not recognize this angle. The metric can be expressed as a 3d hypersphere for its spatial part \[dl^2=R^2(d\chi^2+sin^2\chi d\phi^2\] the 3d hyper sphere is an embedding in 4d space using (x,y,z,w) in the following manner below For some reason trying to insert images messes up latex instructions in the above but in this case its still readable. anyways the above is from the following reference https://jila.colorado.edu/~ajsh/astr3740_14/flrw.pdf see section 10.1 I am considering adding this diagram to the pinn…

You may have heard that the origin of the Moon was due to a small planetary body colliding with the Earth. I believe that this theory is correct and the biggest evidence of this is on the surface of the Moon. We all can see the large dark areas covering the near side of the Moon called Maria, these are very large lava beds that fill very large craters. The Maria filled these craters due to the very deep and intense impacts that created them. The Maria craters are the largest and newest of all the big impacts to occur on the surface of the Moon. Over 90% of the Marias are on the Earth facing side of the Moon, and it is this fact that brings my atte…

If black holes slowly loss mass over time; is there a point where they stop being black holes and devolve into something more like a neutron star? https://news.ubc.ca/2024/04/05/new-gravitational-wave-signal-neutron-stars-and-black-holes/#:~:text=The 'mass gap'%2C spanning,theory than an empty gap. If so; would that explain the potential existence of objects falling within the mass gap between small black holes and neutrons stars? Objects that may have been detected in gravitational wave data? Incredibly old ex-black holes? Dying Holes. If there is a singularity at the center of a black hole, a point of near infinite density, would that same point also…

If the universe is inside a black hole, and each black hole contains a new universe. Wouldn't KK theory where (the fifth dimension is a microscopic extra spatial dimension in the shape of a tiny circle) fit into Schwarzchild cosmology? The idea that each black hole contains a universe could mean that multiple dimensions are contained in every black hole. Size has no relevance in the universe. Everything is either big or small to us because of perspective. If the universe has no beginning or end, but is a continuum; and each universe is contained within a black hole. Then each universe would be smaller than the one before it, and the laws of physics and dimensions cou…

I read that Mars core cooled a long time ago because the planet was small, and Venus's core cooled because of its slow rotation. Does our moon have any affect at all on the Earth's core? Could the size of our moon play a role in keeping the core hot?

https://physics.stackexchange.com/questions/822316/

https://astronomy.meta.stackexchange.com/questions/966/ https://astronomy.meta.stackexchange.com/questions/961/

https://astronomy.stackexchange.com/questions/58066/

What are some massive black holes?

it is true, It required a 100 tons of lifting power for spacemen to landed the moon in 1969?

Does anyone have an idea of the most efficient and expedient way to deflect, redirect, or slow an impending asteroid impact? Obviously, if it is a solid block of metal or rock, just hitting it with a large mass going at a fast enough speed, may change its' velocity enough. Here's my idea I haven't heard about yet. Since asteroids can be a solid block of metal, or rock, or a fragile rubble pile or fluff, or anything in between, catch it with a giant net. Launch a rocket towards the asteroid, and at the correct moment the rocket turns around and decelerates to zero, then accelerates the opposite direction to match the velocity of the asteroid. Then the rocket l…

Sort of a cross disciplinary question here that I've recently been wondering about; Was there a time in the earlier universe when the average temperature of space would have been between 0-100c? If so; for how long and could life have originated then and slowly evolved into extremophile seeding microbes, like tardigrades?

I understand that the model we have goes back to T+10^-43secs. Did spacetime form then ,at that (those?) moment or did it happen when the Higgs field was created? (or emerged?) Since the time it did form ,has it evolved into what we now measure in a continuous fashion?

"In physics, a redshift is an increase in the wavelength" https://en.wikipedia.org/wiki/Redshift "One interpretation of this effect (cosmological redshift) is the idea that space itself is expanding." https://en.wikipedia.org/wiki/Redshift "In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold" https://en.wikipedia.org/wiki/Spacetime Why do we use classical physics and not GR to interpret cosmological redshift as an increase in wavelength and not a decrease in frequency? Why do we allow the metric of space to expand, but not the metric of time, …

hello i would like to ask if there are small radio telescopes that can image stars, galaxies, and universes similar to the larger radio telescopes. thanks very much.

Warning may contain stupid questions. 1. Does Universe has to meet some prerequisite before it can be considered a Universe? 2. Can we have a microscopic Universe? 3. Can there be a Universe withing a Universe? Thx

I was trying to find ways to identify a point anywhere, anytime, any dimension and any universe. Seems the big bang was a good starting point and I think (0,0,0,0,0,0,0,0,0) or (0,0,0,0,0,0,0,0,0,0,0) might reference it. Hey, it's a possible beginning and I wonder if anyone out there thinks I might be onto something.

Hi, I'm a new member, In this topic, we are going to talk about Black Hole Stars. Black Hole Stars were formed by Dark Matter Halo, which creates very massive stars that are million times the mass of the sun. They were so big that even after their birth, more and more gas piled on the newborn star. After a while, the core gets hotter and hotter but the external force crushes the core, making the core a Black Hole! A massive explosion happens but the star is so big that it resists even a supernova! The Black Hole is a few tens of kilometers inside a star, which is the size of the solar system.

Hi About 5 years ago, i think it was a morning, I was walking on a small countryside road in north of France Then I looked on the side and I saw the moon being very huge compared to usually It scared me, i think it looked about twice the size as usual I don't remember well, I took no photo, I think the size decreased pretty quickly, i don't remember well Would someone have an explanation/assumption/idea about this? Could that have been some reflect/visual effect? I think it was during a cold season Regards

Was everything expanding like there was no tomorrow until the Higgs Field " condensed" out of whatever there was before it? And that put a brake on things? Is that when spacetime curvature began ? Was the Higgs Field the last Field to form?

Is it known why Titan happens to have at thick atmosphere when none of the other moons in the solar system do? And from the surface of Titan, is there ever a break in the clouds (doesn't look like it) so that Titanians (I know there arent any but maybe one day) can see Saturn and the sunshine from the surafce? Cheerz GIAN🙂

I'm seeking some (any) online information about small monolith asteroids. . . including info about the kind of rocks that form them. Unfortunately Google search hijacks this simple query by substituting it for rubble pile asteroids (even Wikipedia plays this trick). Try it: type "monolith asteroids" (with quotes) into the Google search bar and see what happens. Weird.

I recently started a topic called "The Speed of Light" and one of the responces said "You're going to have to unlearn this common misconception if you want to actually understand cosmology. The big bang happened literally everywhere and was never a 'point', and there is no rushing of material from a point into 'empty space' so to speak." So Imust be reading the following wrong... The Big Bang was the moment 13.8 billion years ago when the universe began as a tiny, dense, fireball that exploded. Most astronomers use the Big Bang theory to explain how the universe began. But what caused this explosion in the first place is still a mystery. A sphere exploded but…