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Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2022/06/06/200-…ultiverse/

The 200th episode of Mindscape! Thanks to everyone for sticking around for this long. To celebrate, a solo episode discussing a set of issues naturally arising at the intersection of philosophy and physics: how to think about probabilities and expectations in a multiverse. Here I am more about explaining the issues than offering correct answers, although I try to do a bit of that as well.

Continue reading “Mindscape 200 | Solo: The Philosophy of the Multiverse” »

A trio of astrophysicists, two from Colgate University and the third from the University of Texas, has found evidence of dark stars courtesy of data from the James Webb Space Telescope. In their study, reported in Proceedings of the National Academy of Sciences, Cosmin Ilie, Jillian Paulin and Katherine Freese, analyzed three galaxies spotted by the JWST and how they might relate to dark stars.

Back in 2007, Freese, along with Douglas Spolyar and Paolo Gondolo, proposed the idea of a dark star —rather than nuclear fusion, these theorized dark stars are powered by dark matter. Since that time, researchers have continued to study the idea of such a star, built models to show what they might look like and derived a list of characteristics that such a star might have. In the current study, Ilie, Paulin and Freese have found three candidates in Webb data that fit the bill.

Dark stars, the team suggests, likely could have been born during the early days of the universe—like other stars, they would have been made mostly of helium and hydrogen. But they would also contain dark matter—enough to provide a heat source. Such stars would not then be lit by nuclear fusion. If such stars did exist, they would be much larger than other types of stars that have been observed—so large that they might look like galaxies from Earth-based telescopes.

The scientific community has discovered a new planet. It is located 245 light-years away from Earth and has been named TOI-733b. Its size is slightly less than twice the radius of Earth. It has a unique feature: its atmosphere. For now, experts have presented two possibilities. The first is that it may have lost its atmosphere layer. The second is that it could be a “highly irradiated oceanic world.”

This is stated in a study published by the specialized astronomy journal Astronomy & Astrophysics. In the study, it is detailed that this new planet has a density of 3.98 grams per cubic centimeter. To give an idea, it is slightly lower than Earth’s density, which is 5.51 grams per cubic centimeter, but higher than that of our neighbor Mars.

Another point mentioned in the Astronomy & Astrophysics article is that this planet orbits a star slightly smaller than the Sun and completes its orbit in a total of 4.9 days. It is this proximity to the star that serves as an explanation for the first of the two scenarios that scientists have proposed regarding its atmosphere.

A new technique produces perovskite nanocrystals right where they’re needed, so the exceedingly delicate materials can be integrated into nanoscale.

The nanoscale refers to a length scale that is extremely small, typically on the order of nanometers (nm), which is one billionth of a meter. At this scale, materials and systems exhibit unique properties and behaviors that are different from those observed at larger length scales. The prefix “nano-” is derived from the Greek word “nanos,” which means “dwarf” or “very small.” Nanoscale phenomena are relevant to many fields, including materials science, chemistry, biology, and physics.

Our universe could be twice as old as current estimates, according to a new study that challenges the dominant cosmological model and sheds new light on the so-called “impossible early galaxy problem.”

“Our newly-devised model stretches the galaxy formation time by a several billion years, making the universe 26.7 billion years old, and not 13.7 as previously estimated,” says author Rajendra Gupta, adjunct professor of physics in the Faculty of Science at the University of Ottawa.

For years, astronomers and physicists have calculated the age of our universe by measuring the time elapsed since the Big Bang and by studying the oldest stars based on the redshift of light coming from distant galaxies. In 2021, thanks to new techniques and advances in technology, the age of our universe was thus estimated at 13.797 billion years using the Lambda-CDM concordance model.

This post is also available in: עברית (Hebrew)

There are currently thousands of Starlink satellites that belong to SpaceX, and they are causing a lot of disputes in the science and astronomy communities. They are disrupting scientific research by causing streaks in deep space photos, and according to a new study are also dumping “unintended electromagnetic radiation” into space, which could be a major problem for Earth-bound astronauts.

The study published in Astronomy & Astrophysics states that the satellites in low Earth orbit could be muddling or even drowning out signals from deep space that radio astronomers search for.

The discovery of low-level ripples throughout the universe called the gravitational wave background has set physicists looking for exotic explanations.

By Alex Wilkins

Dr. Varsha Ramachandran from the Center for Astronomy of Heidelberg University (ZAH) and her colleagues uncovered the first “stripped” star of intermediate-mass. This discovery marks a missing link in our picture of stellar evolution toward systems with merging neutron stars, which are crucial to our understanding of the origin of heavy elements, such as silver and gold. Dr. Ramachandran is a postdoc in the research group of Dr. Andreas Sander, located at ZAH’s Astronomisches Rechen-Institut (ARI). These results were now published in Astronomy & Astrophysics.

The team of researchers discovered the first representative of the long-predicted, but as yet unconfirmed population of intermediate-mass stripped stars. “Stripped stars” are stars that have lost most of their outer layers, revealing their hot and dense helium-rich core, which results from the nuclear fusion of hydrogen to helium. Most of these stripped stars are formed in binary star systems in which one star’s strong gravitational pull peels off and accretes matter from its companion.

For a long time, astrophysicists have known of low-mass stripped stars, known as subdwarfs, as well as their massive cousins, known as Wolf-Rayet stars. But until now, they have never been able to find any of the so-called “intermediate-mass stripped stars,” raising questions whether our basic theoretical picture needs a major revision.

Year 2020 face_with_colon_three

Behold, the delicious power of pressurized CO₂.