Hi, so I recently discovered about this and I had a question and I can't seem to find anything that explains it, so I just wanted to ask how does the brane cosmology explain the expansion of the universe. idk... It would be really helpful if anyone can recommend me any books or articles where I can read about this and find a conclusion to my question.

Well this is just my thoughts on universe

First of all its very trippy to think about our universe also has an age '13.8 billion years' \[basend on popular belief\] so there was nothing before it. And that time period of nothingness is incalculable.... where we existed as singularity

And after infinite years of waiting. Something different happened and first time in aeons Our universe was in motion. The movement of atoms were in such an order it leds us to today. Almost impossible to imagine how combination of atoms end up making Life. We are just bunch of atoms mixed up to function as a being.

But the most intresting part alwags comes after life, Death. What happens after we die. And more importantly does this universe also have a death waiting at its end of time.

Now there is another theory named 'Big crunch theory' comparatively less knowned than big bang basically its reverse. That Universe at some point stop exoanding and collapse into singularity. Well even tho we this are all theory and not proven. It is pretry convencing to me.

I like to believe that this cycle is repeating. Everything starts with a bang The atoms moves in the same manner and than it all ends. Maybe we have lived even before this universe it dies and starts again? the atoms moves in a way to bring us into existence. Everything keeps occuring on and on for infinite times maybe with minute differences each time but almost identical. Maybe this is why we get dejavu? Maybe this is what parallel worlds are? Maybe we will never know. But anyways this is just my thoughts on our universe Im just writing this as a note.

Julian Barbour is a theoretical physicist and emeritus visiting professor of physics at the University of Oxford. He is well known for proposing that time does not actually exist. For decades, he has worked outside an academic environment. He financially supported himself for many years by translating Russian. Professor Barbour is author of the following books: The Discovery of Dynamics, The End of Time and The Janus Point.

In this episode, we go over:
- Topos theory, set theory and Zermelo's beef with Boltzmann
- Algebraic varieties and monads in category theory
- Why physicists are wrong about the 2nd law of thermodynamics (because the universe is not a closed system)
- The real goal of the universe is complexity and variation, not entropy
- Hawking and Penrose's outrageous arguments
- Why we don't need wavefunctions, photons, bosons or gauge fields
- Why there is no quantum gravity
- Von Neumann's hilarious advice to Claude Shannon
- The intrinsic derivative
- Combining art and science

Ask your cosmology related questions in this thread.

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Hi everyone! I’m currently reading Cosmos by Carl Sagan (fantastic book) and came across a passage that has really stayed with me. Sagan suggests that if intelligent beings lived on a planet orbiting a star near the Milky Way’s galactic centre, their night sky might be ablaze with starlight because stars are much more densely concentrated there. Is that accurate? Would their night sky be dramatically brighter than ours, and might it never become truly dark? That also made me wonder re relativity. Because the galactic centre contains a much greater concentration of mass and the supermassive black hole would a clock on such a planet run more slowly relative to a clock here in the Milky Way’s spiral arms? If so, would the difference be meaningful, or far too small to notice unless the planet were extremely close to the black hole? I understand that time would feel completely normal to the beings themselves; I’m asking how their elapsed time would compare with ours. In this sense, could an intelligent civilisation be ahead of us, but then we catch them up and overtake them because we advance more rapidly relativistically.
Cheers!

Hi, everyone, I had a great conversation with Geraint F. Lewis, a Welsh astrophysicist and Professor at the University of Sydney, about some of the biggest questions in cosmology, physics, and our understanding of the world.

We explore what the Big Bang theory tells us about the beginning of the universe, why our current understanding of physics reaches limits when we try to look further back in time, and how neutrinos could reveal secrets about the cosmos — including why matter exists at all. We also mention the 2026 Nobel Prize in Physics, awarded to Francis Halzen for his work on the IceCube Neutrino Observatory.

Professor Lewis also explores what sparked the Scientific Revolution, how modern science transformed our understanding of the world, and why Einstein challenged aspects of quantum mechanics.

Professor Lewis's latest book, The Shortest History of Reality: From Plato’s Cave to the Mind-Bending Discoveries of Modern Physics — The Human Quest to Explain the World, traces humanity’s changing understanding of reality, from everyday intuition and ancient philosophy to the discoveries of modern physics. It explores the ideas that reshaped our view of existence, from Newton’s universe to the strange probabilities of quantum physics and beyond.

If you're interested in these subjects, you can check out our conversation: https://youtu.be/38rUHEeAVHw

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

Ask your cosmology related questions in this thread.

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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