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Astronomical News

Can we explain dark matter by adding more dimensions to the universe?

By Paul Sutter
First Published 1 day ago
www.livescience.com


Dark matter could be even weirder than anyone thought, say cosmologists who are suggesting this mysterious substance that accounts for more than 80% of the universe's mass could interact with itself.

"We live in an ocean of dark matter, yet we know very little about what it could be," Flip Tanedo, an assistant professor of physics and astronomy at the University of California Riverside, said in a statement.

Every attempt to explain dark matter using known physics has come up short, and so Tanedo and his collaborators are developing exotic models that might better match observations. They asked: What if dark matter interacted with itself through a continuum of forces operating in a space with more dimensions than our usual three? It sounds wild, but their model is able to better explain the behavior of stars in small galaxies than traditional, simple dark matter models. So it's worth a shot.

(...)

As for adding an extra dimension, Tanedo's team has borrowed a trick used in other theories of high-energy particle physics. Through a remarkable, but not yet fully proven, concept known as the AdS/CFT correspondence (the "AdS" stands for anti-de Sitter, which is a kind of space-time, and "CFT" stands for conformal field theory, which is a category of quantum theories), some physics problems that are extremely difficult to solve in our normal 3D space become much easier to grapple with when extended to a four-dimensional space.

By employing this mathematical trick, Tanedo and his collaborators were able to solve how the forces among the dark matter would interact with each other. They could then translate their results to the three dimensions of space and make predictions for how these forces would operate in the real universe. They found that these forces behaved far differently than the forces of nature that we're used to.

(...)

https://www.google.com/amp/s/www.li...-dark-matter-higher-dimensional-universe.html
 
Can we explain dark matter by adding more dimensions to the universe?

By Paul Sutter
First Published 1 day ago
www.livescience.com


"They could then translate their results to the three dimensions of space and make predictions for how these forces would operate in the real universe. They found that these forces behaved far differently than the forces of nature that we're used to."
What... you mean... there's more to our natural world than meets the eye?
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Well I'll be goldarned!
 
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Our universe might be a giant three-dimensional donut, really.

By Paul Sutter - Astrophysicist
livescience.com
19 July, 2021


Imagine a universe where you could point a spaceship in one direction and eventually return to where you started. If our universe were a finite donut, then such movements would be possible and physicists could potentially measure its size.

"We could say: Now we know the size of the universe," astrophysicist Thomas Buchert, of the University of Lyon, Astrophysical Research Center in France, told Live Science in an email.

Examining light from the very early universe, Buchert and a team of astrophysicists have deduced that our cosmos may be multiply connected, meaning that space is closed in on itself in all three dimensions like a three-dimensional donut. Such a universe would be finite, and according to their results, our entire cosmos might only be about three to four times larger than the limits of the observable universe, about 45 billion light-years away.

Physicists use the language of Einstein's general relativity to explain the universe. That language connects the contents of spacetime to the bending and warping of spacetime, which then tells those contents how to interact. This is how we experience the force of gravity. In a cosmological context, that language connects the contents of the entire universe — dark matter, dark energy, regular matter, radiation and all the rest — to its overall geometric shape. For decades, astronomers had debated the nature of that shape: whether our universe is "flat" (meaning that imaginary parallel lines would stay parallel forever), "closed" (parallel lines would eventually intersect) or "open" (those lines would diverge).

(...)

https://www.livescience.com/universe-three-dimensional-donut.html
 
Our universe might be a giant three-dimensional donut, really.

By Paul Sutter - Astrophysicist
livescience.com
19 July, 2021


Imagine a universe where you could point a spaceship in one direction and eventually return to where you started. If our universe were a finite donut, then such movements would be possible and physicists could potentially measure its size.

"We could say: Now we know the size of the universe," astrophysicist Thomas Buchert, of the University of Lyon, Astrophysical Research Center in France, told Live Science in an email.

Examining light from the very early universe, Buchert and a team of astrophysicists have deduced that our cosmos may be multiply connected, meaning that space is closed in on itself in all three dimensions like a three-dimensional donut. Such a universe would be finite, and according to their results, our entire cosmos might only be about three to four times larger than the limits of the observable universe, about 45 billion light-years away.

Physicists use the language of Einstein's general relativity to explain the universe. That language connects the contents of spacetime to the bending and warping of spacetime, which then tells those contents how to interact. This is how we experience the force of gravity. In a cosmological context, that language connects the contents of the entire universe — dark matter, dark energy, regular matter, radiation and all the rest — to its overall geometric shape. For decades, astronomers had debated the nature of that shape: whether our universe is "flat" (meaning that imaginary parallel lines would stay parallel forever), "closed" (parallel lines would eventually intersect) or "open" (those lines would diverge).

(...)

https://www.livescience.com/universe-three-dimensional-donut.html
William Shatner 'Weird or What' informed us via the programme that it's all Bubbles - loads and loads of Bubbles of independent dimensions. I prefer Bubbles, to Doughnuts myself!

'The Notion Of A Flat Universe.' #49

 
Our universe might be a giant three-dimensional donut, really.
What a fascinating article.

I tried this experiment, noted therein:

"For example, take a flat piece of paper. It's obviously flat — parallel lines stay parallel. Now, take two edges of that paper and roll it up into a cylinder. Those parallel lines are still parallel: Cylinders are geometrically flat. Now, take the opposite ends of the cylindrical paper and connect those. That makes the shape of a donut, which is also geometrically flat".

My attempts do not even remotely resemble a donut. :)

I should be better at this, what with having all those years of experience rolling up cigarette papers...

Loved this conclusion:

"While this result technically means that you could travel in one direction and end up back where you started, you wouldn't be able to actually accomplish that in reality. We live in an expanding universe, and at large scales the universe is expanding at a rate that is faster than the speed of light, so you could never catch up and complete the loop".

Is it just myself who recognises this somehow seems like a metaphor of their existence.
 
What a fascinating article.

I tried this experiment, noted therein:

"For example, take a flat piece of paper. It's obviously flat — parallel lines stay parallel. Now, take two edges of that paper and roll it up into a cylinder. Those parallel lines are still parallel: Cylinders are geometrically flat. Now, take the opposite ends of the cylindrical paper and connect those. That makes the shape of a donut, which is also geometrically flat".

My attempts do not even remotely resemble a donut. :)

I should be better at this, what with having all those years of experience rolling up cigarette papers...

Loved this conclusion:

"While this result technically means that you could travel in one direction and end up back where you started, you wouldn't be able to actually accomplish that in reality. We live in an expanding universe, and at large scales the universe is expanding at a rate that is faster than the speed of light, so you could never catch up and complete the loop".

Is it just myself who recognises this somehow seems like a metaphor of their existence.
Maybe a spiral - or an ever expanding tube shaped Bubble would better fit the experiment perhaps?
 
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Enormous balloon could help astronomers get clear view of space​


Set to be launched next April to an altitude of 25 miles, SuperBIT (Superpressure balloon-borne imaging telescope) is a vast balloon the size of a football stadium and the telescope attached to it is expected to provide astronomical imagery comparable to the Hubble telescope, but at a tiny fraction of the cost.

Only thing is, I guess its field of view would be constrained a bit by the humungous balloon directly above it?

https://www.theguardian.com/science...ould-help-astronomers-get-clear-view-of-space
 
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A strange white dwarf star is racing the wrong way through the Milky Way at circa 2 million miles per hour. Recent research findings suggest it's a fragment of a star that underwent a supernova explosion.
Runaway star caught streaking across Milky Way at 2 million mph ... in the wrong direction

In 2017, astronomers noticed a star streaking out of the Milky Way at nearly 2 million mph (3.2 million km/h) — roughly four times faster than our sun orbits — and flying against the direction in which most stars trek around the galactic center. It's also made of completely different star stuff, mostly heavy, "metallic" atoms rather than the usual light elements. LP 40-365, as it was called, was as eye-catching as a wooden car barreling up the interstate against traffic at hundreds of miles per hour.

"It is exceptionally weird in a lot of different ways," said study lead author J.J. Hermes, an astronomer at Boston University. ...

The star moves so quickly that it's headed out of our galaxy for good, which astronomers have taken as evidence that the metallic explorer was launched here by a cosmic catastrophe — a supernova. But they couldn't tell how the supernova had sent it flying. Was LP 40-365 a piece of the exploded star itself? Or was it a partner star flung clear by the shockwave associated with star explosions? A new analysis of old data finds that the star — called a white dwarf — spins about its axis at a leisurely pace — a hint that it is indeed a piece of stellar debris (not a partner star) that managed to survive one of the galaxy's most violent and mysterious events. ...
FULL STORY: https://www.livescience.com/runaway-star-streaks-milky-way.html

PUBLISHED REPORT (Bibliographic Details & Abstract) https://iopscience.iop.org/article/10.3847/2041-8213/ac00a8
 

Strange, repeating radio signal near the center of the Milky Way has scientists stumped​

By Brandon Specktor about 23 hours ago
It's not a fast radio burst, pulsar or low-mass star. So what in the heavens is it?
The center of the Milky Way, as seen by NASA's Chandra, Hubble and Spitzer space telescopes.
The center of the Milky Way, as seen by NASA's Chandra, Hubble and Spitzer space telescopes.(Image credit: NASA / JPL)
Astronomers have detected a strange, repeating radio signal near the center of the Milky Way, and it's unlike any other energy signature ever studied.
According to a new paper accepted for publication in The Astrophysical Journal and posted on the preprint server arXiv, the energy source is extremely finicky, appearing bright in the radio spectrum for weeks at a time and then completely vanishing within a day. This behavior doesn't quite fit the profile of any known type of celestial body, the researchers wrote in their study, and thus may represent "a new class of objects being discovered through radio imaging."
The radio source — known as ASKAP J173608.2−321635 — was detected with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope, situated in the remote Australian outback. In an ASKAP survey taken between April 2019 and August 2020, the strange signal appeared 13 times, never lasting in the sky for more than a few weeks, the researchers wrote. This radio source is highly variable, appearing and disappearing with no predictable schedule, and doesn't seem to appear in any other radio telescope data prior to the ASKAP survey.
 
Not sure if anybody has heard about this yet, as it was a while ago. Hubble took some time lapse shots of a variable star/nebula, and it might be the most beautiful thing ever.

https://esahubble.org/videos/heic1323a/

Also, if anyone has a largish telescope and camera, and is interested in joining doing some citizen science on an apparently very under studied area of astronomy, (variable nebula) or just wants to see another clip of the time lapse, check out this guys YouTube and science efforts here.
 
I love the Hubble's Variable Nebula. The shadows inside it travel much faster than light. This doesn't break relativity, of course, because darkness travels faster than light, as any fule kno.

Light thinks it travels faster than anything, but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it.
Terry Pratchett.
 

Objects at the Solar System’s Edge Are Being Influenced by Something Mysterious


Scientists have discovered hundreds of new objects in the outer solar system using an instrument designed to probe an unexplained source of energy in the universe. The results reveal new insights about the mysterious expanse beyond Neptune, including the possibility that a massive undiscovered planet may be lurking in these dark outer reaches.

1631740001454-gettyimages-84518866.jpeg


A team led by Pedro Bernardinelli, a postdoctoral researcher at the University of Washington, scanned the outer solar system for six years with the Dark Energy Survey (DES), a Chile-based astronomy program whose primary objective is understanding dark energy, an unknown force that’s driving the accelerated expansion of the universe.

The researchers have used the survey to discover a total of 815 trans-Neptunian objects (TNOs), which are minor bodies beyond Neptune.

The survey was especially adept at spotting “dynamically detached” objects and “extreme TNOs” located 150 times farther from the Sun than Earth. These objects have been the subject of much speculation in recent years, because it looks like something in the outer reaches of the solar system is gravitationally tugging at them, causing a clustering effect in their orbits.

One tantalizing explanation for this phenomenon is the existence of a huge planet, about five to ten times the mass of Earth, that is ensconced in the hidden depths of the solar system. This so-called “Planet Nine” would likely be around 400 times as far from the Sun as Earth and may take some 20,000 years to complete an orbit. Scientists have been searching for traces of this planet for years, but have yet to snag a direct detection.

https://www.vice.com/en/article/qj8...-are-being-influenced-by-something-mysterious

maximus otter
 

Strange, repeating radio signal near the center of the Milky Way has scientists stumped​

By Brandon Specktor about 23 hours ago
It's not a fast radio burst, pulsar or low-mass star. So what in the heavens is it?
The center of the Milky Way, as seen by NASA's Chandra, Hubble and Spitzer space telescopes.'s Chandra, Hubble and Spitzer space telescopes.
The center of the Milky Way, as seen by NASA's Chandra, Hubble and Spitzer space telescopes.(Image credit: NASA / JPL)
Astronomers have detected a strange, repeating radio signal near the center of the Milky Way, and it's unlike any other energy signature ever studied.
According to a new paper accepted for publication in The Astrophysical Journal and posted on the preprint server arXiv, the energy source is extremely finicky, appearing bright in the radio spectrum for weeks at a time and then completely vanishing within a day. This behavior doesn't quite fit the profile of any known type of celestial body, the researchers wrote in their study, and thus may represent "a new class of objects being discovered through radio imaging."
The radio source — known as ASKAP J173608.2−321635 — was detected with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope, situated in the remote Australian outback. In an ASKAP survey taken between April 2019 and August 2020, the strange signal appeared 13 times, never lasting in the sky for more than a few weeks, the researchers wrote. This radio source is highly variable, appearing and disappearing with no predictable schedule, and doesn't seem to appear in any other radio telescope data prior to the ASKAP survey.
It's @Swifty's people, asking him to return home...
 
Could have been rocket debris.

Last year, a team of astronomers made a blockbuster claim, saying they had captured the most distant cosmic explosion ever—a gamma ray burst in a galaxy called GN-z11. But that flash of light—supposedly from the most distant galaxy known—has a far more prosaic explanation: It was a glinting reflection from a tumbling, spent Russian rocket that happened to photobomb observers at just the right moment, two new studies claim.

“In the end, I’m of the opinion that this was a fluke,” says D. Alexander Kann, an expert in gamma ray bursts at the Institute of Astrophysics of Andalusia who was not involved in either of the studies.

Gamma ray bursts are the most powerful explosions in the universe. They occur when enormous stars die and collapse into a black hole, or when compact objects such as neutron stars merge into a black hole. Although they happen all the time, the chances of catching one when a telescope is pointed at a particular galaxy are quite slim.

So it was even more surprising when astronomer Linhua Jiang of Peking University and colleagues claimed—using data from the W. M. Keck Observatory in Hawaii—to find a burst coming from GN-z11, a galaxy dating back to a mere 420 million years after the big bang. Indeed, the team itself reported in December 2020 that the odds of catching such a burst were one in 10 billion.

Those odds raised red flags for Charles Steinhardt, an astronomer at the University of Copenhagen. “You start asking,” he says, “‘Are there any other causes that are more likely?’”

That’s where the Russian rocket comes in. Humans have launched and left behind large numbers of objects in orbit around Earth, including satellites, rocket boosters, and even screwdrivers gone missing during spacewalks. Up to half a million bits of metal larger than 1 centimeter are thought to be tumbling around our planet.

Glints of sunlight reflecting off this debris could be responsible for as many as 10,000 flashes of light per hour throughout the night sky, estimates Eran Ofek, an astrophysicist at the Weizmann Institute of Science who has published independent analyses of this phenomenon. The vast majority are invisible to the naked eye, he says, but they can be discernable to astronomical observatories. ...

https://www.science.org/content/art...actually-russian-space-junk-new-studies-argue
 
Cool animations here - and weird astronomical object:
SS 433 is the first discovered "microquasar". A black hole is sucking away matter from its companion star, and shooting out jets of X-rays and hot gas moving at 1/4 the speed of light!
These jets shoot out in opposite directions, and since the black hole wobbles every 162 days, they form spirals. But here's the weird part: a gas cloud 100 light years from SS 433 is pulsing at the same rate! Nobody is sure how it works.
 
Finding 'habitable planets' is one thing but getting there (as we all know) is pretty much beyond our abilities with current technology.
The furthest a 'man made' item has reached (so far) is our 2 'voyager' probes which are only just beyond our solar system.
And that has taken decades.
IIRC the next nearest star is Proxima Centauri (?) which I think is something like 4 light years away. I can't be arsed to check the facts though but think I'm in the right ball park with that one.
But whatever, until some new technology that allows FTL travel comes along, it's out of reach, so the search for 'habitable planets' does seem like a total waste of effort.
 
We've detected about 4000 extrasolar planets so far, and that number is only likely to go up and up. So far, none of these planets has been seen to resemble Earth in any significant way.

Imagine if Captain Kirk had been restricted to fewer than one in four thousand of the planets in Star Trek. In that series, a breathable atmosphere and Earth-like gravity seems to have been the default state for the worlds that he and his motley crew would visit. But in reality Kirk would need to avoid the vast majority of the worlds in the universe in order to walk about in his shirtsleeves.
 
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But whatever, until some new technology that allows FTL travel comes along, it's out of reach, so the search for 'habitable planets' does seem like a total waste of effort.
I'm wondering where the impetus will be for developing a FTL craft if you don't have a destination to point it at ?.
 

Astronomers discover fastest spinning white dwarf star ever observed

One rotation of the Earth takes 24 hours while on J0240+1952 it takes just 25 seconds.

They have established the spin period of the star for the first time, confirming it as an extremely rare example of a magnetic propeller system.

This is when the white dwarf is pulling material from a nearby companion star and flinging it into space at around 3,000 kilometres per second.

University of Warwick astronomers report it is only the second magnetic propeller white dwarf to have been identified in more than 70 years.

The star the Warwick team observed, named LAMOST J024048.51+195226.9 – or J0240+1952 for short, is the size of the Earth but is thought to be at least 200,000 times more massive.

‘The rotation is so fast that the white dwarf must have an above average mass just to stay together and not be torn apart.

Co-author Professor Tom Marsh, from the University of Warwick Department of Physics, said: ‘It’s only the second time that we have found one of these magnetic propeller systems, so we now know it’s not a unique occurrence.

‘It establishes that the magnetic propeller mechanism is a generic property that operates in these binaries, if the circumstances are right.
 
I'm wondering where the impetus will be for developing a FTL craft if you don't have a destination to point it at ?.
A lightspeed probe will only tell us what conditions were on alpha centauri eight years ago, sub light even longer. Any idea of people going there without ftl has the added risk of very old information. I imagine that any Earth or near Earth based information gathering will be at least four years out of date and will offer far less information than a probe at the location. And that's the nearest star. Imagine a four year plus trip to find that a socking great asteroid has just created a nuclear winter!
 
There is always going to be a problem, in a relativistic universe. If you do manage to travel faster than light, it is also possible to travel backwards in time, thanks to the Lorenz transformation and the hypersurface of the present. So you could potentially travel backwards and kill your own grandfather clock (etcetera). In a universe where time travel is possible, causality may be impossible, and if causality is somehow conserved then freewill is impossible. Because of these effects we are much better off in a universe where FTL is impossible.

Better to get used to long travel times and extreme message latency than live in a universe without causality or freewill.
 
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