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Category: cosmology

IT’S BREAKING ALL THE RULES. Ordinarily, a supernova marks the death of a mammoth star, which then briefly outshines an entire galaxy before fading away. Not so for a baffling supernova that went off in a nearby galaxy in 2014. Instead of being the end of the story, the stellar explosion inexplicably began to brighten and has since dimmed, then brightened up again four more times.

If that weren’t odd enough, it turns out a supernova blew up in the same place in the sky more than 60 years ago. Somehow, a star that apparently died around the time Elvis Presley released his first record endured only to die again—truly a “living dead” star.

Astrophysicists suspect this apparent stellar zombie was a rare, colossal type of star with 50 to 100 times the mass of our Sun. The universe’s first stars were similarly huge, they think, though these distant objects lie beyond the reach of even our most powerful telescopes. The re-exploding star could, therefore, be a cosmic anachronism, offering scientists an unprecedented glimpse into the primeval universe.

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We know this dip should be found in the radiowave part of the electromagnetic spectrum, at a wavelength of 21cm.

Challenging measurement

This was all predicted by theory. But in practice, the signal is extremely challenging to find. This is because it overlaps with many other signals in this region of the spectrum which are much stronger – such as common frequencies on the FM radio dial and radio waves from other events in our galaxy. The reason the team eventually succeeded was partly down to the experiment’s sensitive receiver and small antenna, which lets you cover a large area of the sky more easily.

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We know that the universe is expanding, but a strange discrepancy in just how fast that expansion is occurring continues to confound physicists—and make them wonder whether there’s some new, unexplained physics afoot.

For every 3.3 million light years, or one megaparsec, the universe expands around another 70 kilometers per second faster. There are two discrepant measurements of this so-called “Hubble constant.” The light from the most distant parts of the universe reveals an expansion of 68 km/s per megaparsec, while a method taken from extrapolating data from nearby sources reveals a rate of 73 km/s per megaparsec. Scientists can’t explain this discrepancy by chance alone, which means they’re leaving something out, either in their experiments or in the laws of physics. A team of researchers have an idea for another measurement that could help close the gap between these numbers—by measuring how gravity affects the light from distant supernovae.

“If you want to tell the difference between new physics and unknown errors, you need another measurement,” study author Thomas Collett from the University of Portsmouth in the UK told Gizmodo. “If you have measurements that have completely independent methods and they’re all pointing in the same direction, you can robustly believe it’s new physics, not that they’re screwing up in the same way.”

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At the time of the Big Bang, all the matter in the universe was smooshed into an incredibly hot, infinitely dense speck of matter.

But what happened before that? It turns out, famed physicist Stephen Hawking has an answer, which he gave in an interview with his almost-as-famous fellow scientist, Neil deGrasse Tyson. Hawking discusses these ideas and others on the series finale of Tyson’s “StarTalk” TV show, which airs this Sunday (March 4) at 11 p.m. ET on the National Geographic Channel.

Hawking’s answer to the question “What was there before there was anything?” relies on a theory known as the “no-boundary proposal.”

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Your past would theoretically be obliterated and a strange new future would stand before you.

The belief that venturing into a black hole will lead to instant death, with one’s body being torn to pieces, is one that has long pervaded the scientific community, but now a new study by a Berkeley University physicist has suggested that it may actually be possible to fall into a black hole and survive.

Even more intriguing, once inside the black hole, a person may find that their past has been completely obliterated and they could have the opportunity to live many different and strange futures.

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http://www.blogtalkradio.com/cafeesotericaradio/2018/03/02/cafe-esoterica-radio-with-shawn-cohen-do-over-show-with-ira-pastor-regeneration

A team of astronomers led by Prof. Judd Bowman of Arizona State University unexpectedly stumbled upon “dark matter,” the most mysterious building block of outer space, while attempting to detect the earliest stars in the universe through radio wave signals, according to a study published this week in Nature.

The idea that these signals implicate dark matter is based on a second Nature paper published this week, by Prof. Rennan Barkana of Tel Aviv University, which suggests that the signal is proof of interactions between normal matter and dark matter in the early universe. According to Prof. Barkana, the discovery offers the first direct proof that dark matter exists and that it is composed of low-mass particles.

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In a few months, astronomers are going to be pointing their telescopes to Sagittarius A*, the supermassive black hole at the centre of our galaxy.

That’s because it’s going to be buzzed by a closely orbiting star — providing another context for testing Einstein’s theory of general relativity.

The star is called S0-2, one of a class of stars known as S-stars (not to be confused with S-type stars) that closely orbit Sgr A*, which has an estimated mass of around 4.3 million Suns.

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Physicists have confirmed the existence of a new form of atomic nuclei, and the fact that it’s not symmetrical challenges the fundamental theories of physics that explain our Universe.

But that’s not as bad as it sounds, because the 2016 discovery could help scientists solve one of the biggest mysteries in theoretical physics — where is all the dark matter? — and could also explain why travelling backwards in time might actually be impossible.

“We’ve found these nuclei literally point towards a direction in space. This relates to a direction in time, proving there’s a well-defined direction in time and we will always travel from past to present,” Marcus Scheck from the University of the West of Scotland told Kenneth MacDonald at BBC News at the time.

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