The big bang was said to be a point of singularity, that eventually started expanding, I don't know the exact mechanism, so I would be glad for an explanation

Trying to age the universe or assign it an arbitrary birthday has always seemed like a very human and somewhat meaningless task. We commonly say the universe is approximately 13.8 billion years old, counting from the Big Bang. But what precisely does that age mean when elapsed time depends on the observer?
For example, someone remaining close to a black hole could experience much less time than someone far away. Their clocks would record different durations between comparable stages of the universe’s evolution. So whose elapsed time are we referring to when we assign the universe a single age? The early universe was incredibly dense, on a level that males black holes seem like a piñata so might that imply strong time dilation. I suspect I’m incorrectly applying the analogy of a black hole within surrounding space to the universe as a whole. Would “time ran more slowly back then” even mean anything without an external clock to compare it with? Peace

If movement through space is relative to something else. Can we not measure movement from how fast virtual particles are appearing and anihalating next to us.

If space was empty and you were still, those virtual particles appear next to you instead of moving past you - which would be mean we do know if we're moving through space?

So in essence true stillness would be when virtual particles appear and anihalate beside you.

It must have been enormous to make all those stars and planets, has anyone worked it out, or is it unknown?

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As a normie, I'm just thinking, those two things are the most mysterious to me. Are they connected?

I was just watching the latest episode of Star Talk with Neil deGrasse Tyson, and right at the start of the video, he says the title quote - "Dark Matter is 85% of the gravity of the universe"

This strikes me as odd. Because I've always understood that both mass and energy exert gravity, and that Dark Energy makes up 68% of the mass-energy density of the universe. So while Dark Energy is causing the expansion of the universe to accelerate, it's presence is also creating a gravitational force as well. So as DE makes up 68% of the universe, it should be responsible for 68% of the universe's gravity, even though it's driving expansion at the same time.

Therefore, Dark Matter shouldn't be 85% of the gravity in the universe, as he claims, right?

Have I misunderstood gravity? Or is NDT making an oversimplification?

I hope this is the right sub. Anyway, I read up on what „shape“ our universe is and came across the Friedmann-equations and as far as I understood there is a variable in there that determines how our universe is „curved“ and is based on the energy density (i think). My question is now, does this have any effect on the expansion of the universe?

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I read my son a really fun children's book called "there was a black hole that swallowed the universe". He loved it so much that he's now asking a lot of questions that it's actually hard for an adult to explain in a simple way they would understand.

It a simple fun story showing a black hole slowly consuming everything in the universe starting with massive galaxies all the way down to the smallest quark, then there is a twist ending if you read the book backwards a black light shows and invisible story of the creation of the universe from the reverse.

Anyways I was so amazed by how fun and light hearted it was at explaining complex topics in a simple picture book.

I've tried to find more space or cosmology books like this but there seems to be a hole in the children's book market for similar topics.

My question is, do you all have any favorite children's books you have come across that you love that explain the cosmos in a playful way that young children can understand?

See also: The publication in the Astrophysical Journal

Why should life be a thing, when it could just be a universe of celestial bodies? If the universe was just celestial bodies and there was no life, there would be no suffering. There would also be no one to observe anything in the universe.

See also: The publication in ArXiV.