#cosmology

#cosmology

Here in our Universe, one great mystery is how, if matter and antimatter can only be created or destroyed in equal-and-opposite amounts, our Universe came to be dominated by normal (regular) matter, with barely a trace of antimatter present. Sure, dark energy (68%) and dark matter (27%) might make up the majority of the Universe, but the rest of it is made up of particles from the Standard Model: quarks, gluons, leptons, and photons. Of that 5%, nearly all of it (4.9%) is regular matter, made of protons, neutrons, and electrons, while the amount of antimatter - like antiprotons, antineutrons, or positrons - is negligible.

Cosmologists are now fairly certain that our universe is flat. But that doesn't explain the exact shape of space. It could extend infinitely along the three spatial dimensions or resemble a three-dimensional generalization of a donut's surfaceor take on even wilder forms. The mathematics of flat space is astonishingly versatile, and new research is upending the traditional thinking about the layout of our cosmos.

Space is filled with cosmic voids—vast regions mostly free of matter that have opened between dense threads of material that make up a cosmic web. Far from being vacant backwaters with little to study, these voids may hold solutions to some of the most persistent cosmic mysteries, such as the behavior of gravity, the nature of dark energy, and the so-called Hubble tension, an observational mismatch in the expansion rate of the universe that has caused astronomers' headaches for years.

Out there in the Universe, there's so much that we've learned and discovered. We know all about the normal matter present in the Universe: the full suite of Standard Model particles and how they interact all throughout cosmic history. We know about the laws that govern reality extremely well, including the fundamental forces and how they behave under a wide variety of cosmic and quantum conditions. We've reconstructed most of the history of the Universe in extraordinary detail, and from a variety of different approaches - observationally, theoretically, and experimentally - we're gathering more and more evidence every day to peel back the curtains that obscure what's beyond the currently understood frontiers governing reality.

If all you start with are the fundamental building blocks of nature - the elementary particles of the Standard Model and the forces exchanged between them - you can assemble everything in all of existence with nothing more than those raw ingredients. That's the most common approach to physics: the reductionist approach. Everything is simply the sum of its parts: no more and no less. These simple building blocks, when combined together in the proper fashion, can come to build up absolutely everything that could ever exist within the Universe and explain the full suite of phenomena that have ever occurred, with absolutely no exceptions.

A metastable or 'false' vacuum is a hypothetical state that seems stable but hasn't actually reached its most stable state yet, posing a potential doomsday threat.

The precise expansion rate of the universe - called the Hubble constant - has turned into a major pain point as attempts to nail it down keep leading to widely differing figures.

Star-formation will eventually end, and then the last shining stars will burn out. Galaxies will dissociate due to gravitational interactions, ejecting all masses and leaving only supermassive black holes behind. And then those black holes will decay via Hawking radiation, leaving only cold, stable, isolated bodies, from which no further energy can be extracted, all accelerating away from us within our dark energy-dominated Universe.

Okay, first thing first: the universe is in fact expanding. We've known this for more than a century now, and it's the basis for modern cosmology. This idea is called the big bang modelwhich is an unfortunate name because it brings to mind a cosmos expanding like an explosion, with galaxies moving away from each other through space like shrapnel. But in fact space itself is expanding, and that's different.

A key goal, writes the author, Bobby Azarian,is to argue against the view that life is an unlikely accident that may have emerged only once on one tiny speck in a vast universe, and that it is certain to disappear as the universe's free energy dissipates in accordance with the second law of thermodynamics. He argues that while such a conclusion had for several generations seemed to be the destination to which clear-headed scientific exploration had brought mankind,

Every day, we have a choice whether we take our lives, our existence, our freedoms, and our moments for granted, or whether we express appreciation and gratitude for the good things that exist. The biggest unifier that all human beings have in common, that we all exist on the same world and in the same Universe, never gets the due it deserves. Here and now, it's possible for us to exist, and to exist as long as our natural lifespans will allow us.

By observing the brightness of distant dying stars, astronomers have long come to believe that the expansion of the universe is accelerating. In fact, that apparent reality is deeply built into cosmological models: a mysterious force that influences the universe on the largest scales, dubbed dark energy, is believed to explain the acceleration. However, not everybody agrees with this widely accepted scientific consensus.

Modelling shows how the infant Universe might have stayed warm and dense during its primoridal expansion.

Along with John Mather of the NASA Goddard Space Flight Center, Smoot won the 2006 Nobel Prize for physics for finding the background radiation that finally pinned down the Big Bang theory, the idea that the universe was born in a rapid cosmic expansion some 14 billion years ago. The Florida native earned a PhD in particle physics at the Massachusetts Institute of Technology in 1970.

It sounds like something from the latest science fiction blockbuster. But scientists in Massachusetts have revealed the terrifyingly high odds a black hole will explode in the next 10 years. In a new paper, they say there's a 90 per cent chance of at least one black hole exploding by 2035. If and when it happens, telescopes positioned in space and here on Earth should be able to capture the event - which fortunately won't be dangerous for Earthlings.

When most of us think about science, we don't often think about something very fundamental to the enterprise: what the goal of it all actually is. Reality is a complicated place, and the only tools we have to guide us in understanding what it is and how it works is the combination of what we can observe, measure, and experiment on.

NASA explains the incredible shot captured by the Hubble Space Telescope of 3I/ATLAS shows a 'teardrop-shaped cocoon of dust' trailing behind the object, suggesting it's a sizable comet.