I've been working on a small tool called hpvis, a viewer for HEALPix sky maps (CMB maps, dust maps, masks and so on).

I wanted something that opens a big map instantly and lets me look around, without writing a plotting script every time. So the whole thing is rendered on the GPU. You can open maps up to nside 8192, zoom in, rotate the sky and switch between projections (Mollweide, Hammer, Mercator, Gnomonic and a few more) in real time.

A few things I use all the time:
- FITS and .npy files, RING or NESTED
- Masks, histograms and power spectra in docks next to the map
- Select a region and get its statistics on their own

It's built with C++, Qt6 and OpenGL, and it's still early, so feedback and bug reports are very welcome.

Code Repo: https://github.com/dheerajshenoy/hpvis

See also: The publication in ArXiV

I think I learned about cosmic inflation mainly from people that were very optimistic that it is factual. Sure it has room to be wrong due to the nature of science, but it was practically leading consensus.

I think it’s not quite like that, like it does seem like the leading consensus view but only cautiously and not a lot of people want to get serious about what that means if it is true. I notice “what came before the big bang” is still considered an open question despite cosmic inflation apparently giving an answer to that.

I think the model is right and the conditions it lays out to be roughly accurate to reality. But I’m curious what skeptics feel too or maybe if people think the model is somewhat true?

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.

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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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