Although cosmic inflation is well known for resolving some important mysteries about the structure and evolution of the universe, other very different theories can also explain these mysteries. In some of these theories, the state of the universe preceding the Big Bang – the so-called primordial universe – was contracting instead of expanding, and the Big Bang was thus a part of a Big Bounce.
During a keynote speech at a NASA conference a decade ago on the search for extraterrestrial life an attendee shouted out: “We have no idea what’s out there!” One of NASA’s goals is to search for life on other planets like Mars, where there was once flowing water and a thick atmosphere, or moons of the outer solar system like Europa and Enceladus, where vast water oceans churn under thick layers of ice. But what if life on those worlds doesn’t use our DNA? How could we recognize it? A 2019 DNA breakthrough may be the key to answering these questions and many more.
Determining the age of a star can be one of the trickiest measurements an astronomer can make. Stars don’t obviate their age like humans do — with wrinkles around the eyes, grey hair, or brittle bones. Instead stars give hints at their age through things like their motion, rotation rate, chemistry, and placement in the Galaxy. Finding “extrema” on the age spectrum for stars — the oldest and youngest — is much easier than trying to find middle aged objects like our Sun. In this article, we reveal five fast facts about the youngest stars in the Galaxy.
“There are precious few fossil relics of the early Universe,” Brian Keating, Chancellor’s Distinguished Professor of Physics at UC San Diego, and author of Think Like a Nobel Prize Winner,” told The Daily Galaxy. “Just after the Big Bang,” Keating explained, “came the epoch of Big Bang nucleosynthesis, ending a few minutes later. The Cosmic Microwave Background, the universe’s oldest light, came about 380,000 years later. Then the great cosmic darkness began. That darkness had to end, or else we would not be here asking what caused the Universe to be so dim.
One of the major problems in understanding the formation of galaxies is that approximately 80% of the baryons that make up the normal matter of galaxies is missing, expelled over eons from galaxies into inter-galactic space by the galactic winds created by stellar explosions.
“Something like the diffuse glow of gamma ray background that permeates our Milky Way Galaxy could conceivably be evidence for dark matter,” researcher Mark Krumholz, a theoretical and computational astrophysicist at Australian National University, told The Daily Galaxy.
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