The physical reason behind quantum uncertainty
Starts With A Bang!
by Ethan Siegel
22h ago
Today, the Universe has evolved into the complex, life-friendly place we know it to be because we were able to form neutral atoms early on in the Universe. Yet without just the right quantum properties, the formation of stable, neutral atoms would have been delayed significantly, or might not have even occurred at all. (Credit: agsandrew / Adobe Stock and remotevfx / Adobe Stock)No matter how good our measurement devices get, certain quantum properties always possess an inherent uncertainty. Can we figure out why? Perhaps the most bizarre property we’ve discovered about the Universe ..read more
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Why humanity must invest in exploring the Universe
Starts With A Bang!
by Ethan Siegel
2d ago
At left is the iconic view of the Pillars of Creation as seen by Hubble. Beginning in 2022, JWST (at right) has viewed the pillars as well, revealing details such as newly forming stars, faint protostars, and cool gas that are invisible to even Hubble’s impressive capabilities. (Credits: NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI))There are so many problems, all across planet Earth, that harm and threaten humanity. Why invest in researching the Universe? It’s no secret that there is a seemingly endless string of problems to address in ..read more
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The compelling case for axions as our dark matter
Starts With A Bang!
by Ethan Siegel
2d ago
Axions, one of the leading candidates for dark matter, may be able to be converted to photons (and vice versa) under the right conditions. If we can cause and control their conversion, we might discover our first particle beyond the Standard Model, and possibly solve the dark matter and strong CP problems as well. This would imply that we do live in a Universe with strong CP-violation, but only a tiny amount of it: below the experimental and observational thresholds. (Credit: Sandbox Studio, Chicago, Symmetry Magazine/Fermilab and SLAC)The majority of the matter in our Universe isn’t made ..read more
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How we know the Universe is 13.8 billion years old
Starts With A Bang!
by Ethan Siegel
4d ago
If you look farther and farther away, you also look farther and farther into the past. If the number of galaxies, the densities and properties of those galaxies, and other cosmic properties like the temperature and expansion rate of the Universe didn’t appear to change, you’d have evidence of a Universe that was constant in time; that is not what we see. (Credit: NASA/ESA/STScI/A. Feild)The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age? According to the theory of the hot Big Bang, the Universe had a beginnin ..read more
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Starts With A Bang podcast #104 — The magnetized galactic center
Starts With A Bang!
by Ethan Siegel
6d ago
This image shows the magnetized galactic center, with various features highlighted, as imaged by the SOFIA/HAWC+ FIREPLACE survey team. The giant bubble at the left of the image is some 30 light-years wide, several times larger than any other supernova-blown bubble ever discovered. (Credit: D. Paré et al., arXiv:2401.05317v2, 2024)Starts With A Bang podcast #104 — The magnetized galactic center The center of the galaxy doesn’t just host stars and a black hole, but an enormous set of rich gassy and dusty features. Find out more! Have you ever wondered what the full story with the gala ..read more
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What was it like when human beings transformed the Earth?
Starts With A Bang!
by Ethan Siegel
1w ago
The original “blue Marble” image, from Apollo 17, was actually snapped in the orientation shown here: where south is at the top and north is (invisibly) on the other side of the world. This image is now more than 50 years old, as humanity has transformed our planet in a myriad of ways both leading up to, and since, this image was obtained. (Credit: NASA/Lunar and Planetary Institute)Although human beings arrived on Earth just ~300,000 years ago, we’ve transformed the entire planet completely. Here’s how we did it. When each of us is first born into this world, it might feel like the world ..read more
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What was it like when humans first arose on planet Earth?
Starts With A Bang!
by Ethan Siegel
1w ago
70,000 years ago, a brown dwarf pair known as Scholz’s Star, right on the precipice of igniting hydrogen fusion in its core, passed through the Solar System’s Oort cloud. Stars, failed stars, and stellar remnants pass through our Solar System multiple times every million years. Both modern humans and Neanderthals were likely around to see this event. Unlike the illustration, however, it’s so intrinsically faint that it still wouldn’t have been visible to human eyes; today, it’s approximately 22 light-years away. (Credit: José A. Peñas/SINC)Despite billions of years of life on Earth, humans fir ..read more
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What was it like when mammals appeared and thrived?
Starts With A Bang!
by Ethan Siegel
1w ago
During the Cambrian explosion, some 550–600 million years ago, the first complex, differentiated, macroscopic, multicellular, sexually-reproducing animals came to dominate the oceans. Over the next half a billion years, evolution would take life in many different directions. By the time the asteroid eliminating the dinosaurs arrived, 65 million years ago, mammals had diversified in a number of directions, with the earliest primates splitting off just before that great event. Modern lemurs, shown here, likely bear a strong resemblance to those early primates. (Credit: Bas Czerwinski/AFP/Getty I ..read more
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What was it like when life on Earth became complex?
Starts With A Bang!
by Ethan Siegel
1w ago
Somewhere around 550 million years ago, an enormous abundance and diversity of large plants and animals begins showing up in the fossil record: an event known as the Cambrian Explosion. Roughly around this time, life became enormously complex and differentiated on Earth: a sharp contrast to the prior 4 billion years of terrestrial history. (Credit: James St. John/flickr)For billions of years on Earth, life was limited to simple unicellular, non-differentiated organisms. In a mere flash, that changed forever. A single look at Earth today, with enormous plants, animals, and fungi dominating ..read more
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Ask Ethan: How do symmetries lead to conservation laws?
Starts With A Bang!
by Ethan Siegel
1w ago
Emmy Noether, the person who proved Noether’s theorem, which connects symmetries and invariances of a theory with an associated conserved quantity. At right, the illustration of conservation of linear momentum, a consequence of spatial-translation invariance, is shown. (Credit: Mathematical Association of America (L)/R Nave (R))First derived by Emmy Noether, for every symmetry a theory possesses, there’s an associated conserved quantity. Here’s the profound link. In this Universe, there are certain physical quantities that are — quite importantly — always conserved. Laws like the “co ..read more
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