Gravitational waves helping to expose black holes, dark matter and theoretical particles

Gravitational waves helping to expose black holes, dark matter and theoretical particles
When two objects such as black holes or neutron stars merge, they cause the frequency of the gravitational waves to increase, which would sound like a chirp. Credit: LSC/Alex Nitz

Gravitational waves – the invisible ripples in the fabric of space predicted by Albert Einstein – are opening up a new era of astronomy that is allowing scientists to see parts of the universe once thought to be invisible, such as black holes, dark matter and theoretical subatomic particles called axions.

Almost 100 years after Einstein predicted their existence as part of his theory of general relativity, gravitational waves were first detected in 2015 by scientists working on the Laser Interferometer Gravitational Waves Observatory (LIGO), earning them the Nobel Prize in physics.

The faint disturbances the giant instrument picked up were created by two crashing into one another 1.3 billion from Earth. As these two super-heavy objects collided, they deformed space and time.

"The deformation propagates out like ripples on a lake," explained Professor Paolo Pani, a theoretical physicist at Sapienza University of Rome, Italy. "These are gravitational waves."

All objects with mass will create their own slight dip in the fabric of spacetime, creating what we call gravity. But only cataclysmic events involving the heaviest objects, such as black holes and , can create gravitational waves big enough to be detected on Earth. They radiate out across the universe at the speed of light, passing through almost everything in their path.

But the ability to detect these waves is also now providing astronomers with new ways of looking at the universe. Prof. Pani is leading the DarkGRA project in an attempt to use gravitational waves to probe some of the biggest mysteries of the universe, including heavy exotic stars, and black holes themselves.

Previously astrophysicists have been forced to infer the presence of black holes by looking at the behaviour of the material around them. Thought to be the super-heavy remains of collapsed stars, the gravity they produce is so great that not even light escapes. Anything that passes the boundary of a black hole, known as the event horizon, stays there.

"This is why we cannot see black holes," said Prof. Pani. "Instead we see an absence of light from them. Black holes are a big mystery still."

Gravitational waves, however, are allowing scientists like Prof. Pani to view them directly. "They are sort of a messenger of the spacetime around these objects, without using any intermediate," he said.

By studying the features of these waves it is possible to obtain information about the mass, rotation, radius and speed of these previously invisible objects. "The goal of our project is to understand the gravitational wave observations from very compact objects, so we can rule out or confirm other types of objects," said Prof. Pani.

According to general relativity, the merger of two very compact objects – such as white dwarfs, neutron stars or black holes – will cause the final to collapse to form a black hole. But there are alternative theories that predict they could also form objects of a similar mass and radius to black holes, but without an event horizon. These mysterious compact objects would therefore have a surface that would reflect gravitational waves.

"If there is a surface, after a merger of the objects, there should be gravitational wave echoes, so a signal that is reflected from the surface," Prof Pani explained. It should be possible to detect these echoes in the signals picked up here on Earth.

Dark matter

There is another explanation, however, that would lead to black holes unexpectedly producing echoes or other unexplained gravitational wave features – they could be sitting in a bath of dark , a hypothetical form of matter that has yet to be seen but is thought to account for 85% of all matter in the universe. This too could produce a distinctive tell-tale gravitational wave.

"Dark matter interacts very little with anything else, so is very difficult to test in the lab," said Prof. Pani. But by looking for distinct signals in the gravitational waves it could allow scientists to 'see' it for the first time.

Some gravitational observations can only be explained either by the presence of dark matter, which we cannot see, or by changing our laws of gravity. Professor Ulrich Sperhake, a at the University of Cambridge, UK, and lead scientist in the StronGrHEPproject, described gravitational waves as a 'new window onto the universe' that could help us unravel these mysteries.

If there is all this dark matter hanging around two black holes as they merge, then this would soak up energy.

It would mean that in a black hole collision like that detected by LIGO, the gravitational waves would look a bit different than it would without dark matter.

One observational puzzle they could shed light on is why galaxies rotate faster than their size suggests they should. "The speed of rotation is related to the mass that is inside," said Prof. Sperhake. So if a galaxy is spinning faster than the mass we can see, there are two possible explanations: we either need to alter our fundamental theories of how gravity works or there is dark matter in the galaxies that we cannot see.

An idea Prof. Sperhake is investigating is to extend Einstein's general relativity with a new theory, dubbed scalar tensor gravity. This suggests that the universe is filled with an extra field – similar to a magnetic or electrical field – that has yet to be detected.

It would mean that the supernova explosion of a dying star would not only be visible as a burst of gravitational waves, but there would be an afterglow of gravitational waves that we might detect. We could direct LIGO to regions of the sky where stars have exploded – known as supernovae – to try to detect such an afterglow from the scalar field that may persist centuries after the actual explosion.

Separately, Prof. Sperhake is investigating if dark matter could be explained by theoretical subatomic particles called axions. He is trying to model what the echoes of gravitational waves from black holes might look like if these particles are present.

"I would say axions are one of the best candidates for dark matter," he said. The next step is to apply his models to the data that LIGO gathers to see if theory and observation are a match.

Beautiful theory

Dr. Richard Brito joined Prof. Pani's group in Italy earlier this year as part of his own project, FunGraW to use to test the existence of axion particles. But he will also be using them to test Einstein's theory itself and whether it may be incorrect at vast scales.

"If we see objects almost as compact as black holes but without an event horizon, that means that general relativity is wrong at those scales," he said.

It could have important everyday implications. The theory of general relativity is crucial to the daily operation of GPS for example. But finding that Einstein's theory breaks down at large scales does not mean it should be thrown out. Rather, an addendum might be needed.

"You'd have a hard time matching the mathematical clarity of Einstein's theory," said Prof. Sperhake. "It is not only amazing because of all the fantastic predictions it does. It has the appeal of being a beautiful theory. And physicists interestingly regard beauty as an important ingredient in a ."


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Apr 05, 2019
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

Displaced supersolid dark matter is curved spacetime.

In the Bullet Cluster collision the dark matter has not separated from the ordinary matter. The collision is analogous to two boats that collide, the boats slow down and their bow waves continue to propagate. The water has not separated from the boats, the bow waves have. In the Bullet Cluster collision the galaxy's dark matter displacement waves have separated from the colliding galaxies, causing the light to lense

Apr 05, 2019
^^^^^Utter crap. And stop posting the same thing, time after time, you clown. Read the comments guidelines.

Apr 05, 2019
Particles of ordinary matter move through and displace the supersolid dark matter, causing it to wave. Wave-particle duality is a moving particle and its associated wave in the supersolid dark matter.

The supersolid dark matter ripples when galaxy clusters collide and waves in a double-slit experiment, relating general relativity and quantum mechanics.

Apr 05, 2019
Define 'supersolid'. Please. Do.

(and then we can go through the other crap you post word by word)

Apr 05, 2019
If dark matter were a superfluid it would be displaced equally everywhere by the Earth and would not cause gravity.

The further from the Earth you get the less the supersolid dark matter is displaced by the Earth, similar to how the further from the Earth you get the less the mathematical construct of spacetime is curved by the Earth.

Apr 05, 2019
If dark matter were a superfluid it would be displaced equally everywhere by the Earth and would not cause gravity.

The further from the Earth you get the less the supersolid dark matter is displaced by the Earth, similar to how the further from the Earth you get the less the mathematical construct of spacetime is curved by the Earth.


Which is still gibberish, and does not answer AP's question.

Apr 05, 2019
The supersolid dark matter behaves like a solid that is displaced by the particles of ordinary matter that exist in it and move through it. The quarks the Earth consists of displace the supersolid dark matter. The displaced supersolid dark matter pushes back. The supersolid dark matter displaced by the quarks the Earth consists of, pushing back and exerting pressure toward the Earth, is gravity.

Apr 05, 2019
The supersolid dark matter behaves like a solid that is displaced by the particles of ordinary matter that exist in it and move through it. The quarks the Earth consists of displace the supersolid dark matter. The displaced supersolid dark matter pushes back. The supersolid dark matter displaced by the quarks the Earth consists of, pushing back and exerting pressure toward the Earth, is gravity.


Gibberish^2

Apr 05, 2019
The reason for the mistaken notion a galaxy is missing dark matter is that the galaxy is so diffuse that tit doesn't displace the supersolid dark matter outward and away from it to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up.

It's not that there is no dark matter connected to and neighboring the visible matter. It's that the galaxy has not coalesced enough to displace the supersolid dark matter to such an extent that it forms a halo around the galaxy.

A galaxy's halo is not a clump of dark matter traveling with the galaxy. A galaxy's halo is displaced supersolid dark matter.

Apr 05, 2019
The reason for the mistaken notion a galaxy is missing dark matter is that the galaxy is so diffuse that tit doesn't displace the supersolid dark matter outward and away from it to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up.

It's not that there is no dark matter connected to and neighboring the visible matter. It's that the galaxy has not coalesced enough to displace the supersolid dark matter to such an extent that it forms a halo around the galaxy.

A galaxy's halo is not a clump of dark matter traveling with the galaxy. A galaxy's halo is displaced supersolid dark matter.


Gibberish cubed. Give it a rest, you clown.

Apr 05, 2019
Bob...you make absolutely zero sense.

Soooo...onto the block list you go.

Apr 05, 2019
Define 'supersolid'. Please. Do.

(and then we can go through the other crap you post word by word)


I repeat AP's post for clarity. Describe it, preferably with reference to the scientific literature, or stop posting the same old rubbish. It will be reported.

Apr 05, 2019
'Astronomers Discover New Galaxy That Is 99.99% Dark Matter'
https://www.popul...-matter/

> "A relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue."

The more compact the cluster the greater the displacement of the supersolid dark matter connected to and neighboring the cluster, the greater the displaced supersolid dark matter pushes back and exerts pressure toward the cluster, the faster the stars in the cluster move.

Apr 05, 2019
'Astronomers Discover New Galaxy That Is 99.99% Dark Matter'
https://www.popul...-matter/

> "A relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue."

The more compact the cluster the greater the displacement of the supersolid dark matter connected to and neighboring the cluster, the greater the displaced supersolid dark matter pushes back and exerts pressure toward the cluster, the faster the stars in the cluster move.


Does not answer the question; WTF is supersolid DM?

Apr 05, 2019
'The Milky Way's dark matter halo appears to be lopsided'
http://arxiv.org/abs/0903.3802

> "the dark matter halo of the Milky Way is dominantly lopsided in nature."

The Milky Way's halo is lopsided due to the ordinary matter in the Milky Way moving through and displacing the supersolid dark matter, analogous to a submarine moving through and displacing the water.

Apr 05, 2019
n search of black holes and dark matter astrophysicists are relying on indirect observations. It would seem that the measurement of the event horizon of a black hole directly would be a direct evidence. However, by the nature of a horizon, any real measurement of the event horizon will be indirect. The Event Horizon Telescope will get picture of the silhouette of the Sgr A* which is due to optical effects of spacetime outside of the event horizon. The result will be determined by the simple quality of the resulting image that does not depend on the properties of the spacetime within the image. So, it will be also indirect and an existence of BH is a hypothesis.
https://www.acade...ilky_Way

Apr 05, 2019
Purely to inform those who do not know what the physics term/state "supersolid" implies, here is a wiki excerpt:
In 2017, two research groups from ETH Zurich and from MIT reported on the first creation of a supersolid with ultracold quantum gases. The Zurich group placed a Bose-Einstein condensate inside two optical resonators, which enhanced the atomic interactions until they start to spontaneously crystallize and form a solid that maintains the inherent superfluidity of Bose-Einstein condensates.[8][9] The MIT group exposed a Bose-Einstein condensate in a double-well potential to light beams that created an effective spin-orbit coupling. The interference between the atoms on the two spin-orbit coupled lattice sites gave rise to a density modulation that establishes a stripe phase with supersolid properties.
The following link goes direct to "experiments" section:

https://en.wikipe...eriments

See the last paragraph in that section.

Cheers.

Apr 05, 2019
Bob: matter attracts matter gravitationally, dark matter attracts baryonic matter gravitationally, matter attracts matter gravitationally (if repetition is so efficacious for falsehood, can't hurt repeating the observable truth; humans apparently have a subtle neurochemical addiction to cognitive ease). Bob, matter attracts matter gravitationally, it's really true.

Bob, you could maybe try arguing matter displaces spacetime, but if you compare the location of coordinates in flat spacetime with their "curved" location in the presence of matter, you'll see that the coordinates are contracted inward towards the matter, not displaced outward away from the matter.

Apr 05, 2019
Gravity is not a pull. The Moon does not physically pull on the ocean water. There is no rope.

The supersolid dark matter displaced by the Moon pushes back and exerts pressure toward the Moon. The supersolid dark matter displaced by the Earth pushes back and exerts pressure toward the Earth.

The supersolid dark matter between the Moon and the Earth is more at relativistic rest than the supersolid dark matter encompassing them which allows the ocean water to rise which exists between the Moon and the Earth. The superoslid dark matter which encompasses the Earth and the Moon pushes the solid matter Earth closer to the Moon than it does the ocean water opposite the Moon which allows the tide to 'rise' opposite the Moon.

Apr 05, 2019
Gravity is, and gravity does. Because it has no countervailing force, it is after all is said and done the most powerful force in the universe over long distances.

Proper understanding of gravity has guided NASA probes to Pluto. Where they took pictures.

Just sayin'.

Apr 05, 2019
Funny how these memes get repeated over an over. Einstein did not predict gravitational waves and in fact opposed the idea.

It was Poincare shortly after Einstein's Special Relativity and Minkowski's Space-Time model who first proposed Gravitational Waves. After General Relativity in 1915 a number of researchers suggested to Einstein that his equations predicted gravitational waves but Einstein was unconvinced. In 1916 he applied the equations to the problem and discovered that two kinds of Gravitational Wave were theoretically possible but this was due to errors in his calculations which were corrected by others in the 1920s. Einstein made attempts to disprove the actual existence of gravitational waves in the 1930s.

Einstein opposed the reality of gravitational Waves and Black Holes and yet is still characterised as being their predictor and champion. Why??

Apr 05, 2019
_"..to see parts of the universe once thought to be invisible, such as black holes, dark matter and theoretical subatomic particles called axions."_ LOL, seperates "Dark Matter" and "Axions" - what a troll! ;O)-

Apr 05, 2019
@RKS, perhaps you have not seen this paper: https://einsteinp...trans/33

Apr 05, 2019
And, of course, @RKS, you have not considered that these gravitational waves have been measured, not to mention tied to an event seen by many astronomical observatories both on Earth and in orbit.

Apr 05, 2019
Correct observations do not mean correct conclusions.

Apr 06, 2019
But correct predictions do.

Apr 06, 2019
Details (and interesting interviews and histprical detail!) on the LIGO/VIRGO updates here: https://news.stan...pgrades/ ].

I am all for testing GR and dark matter, so this activity is nice. However I find it ironic that the gravitational wave observations that mostly killed off alternatives are still used to peddle them. "Troubled Times for Alternatives to Einstein's Theory of Gravity. New observations of extreme astrophysical systems have "brutally and pitilessly murdered" attempts to replace Einstein's general theory of relativity."

(And personally I have less hope to see axions in a seemingly anthropic universe - but you don't know until you try.)

Apr 06, 2019
Pet peeve: "Gravitational waves, however, are allowing scientists like Prof. Pani to view them directly. "They are sort of a messenger of the spacetime around these objects, without using any intermediate," he said."

This is still not a testable definition of "direct", which seems to me to be personal opinion based. It is not like we can read out the data stamped in the fields "directly" but always use intermediates like EM - in LIGO laser interferometry and heavy signal modeling.

Besides Pani himself admitting to seeing messenger intermediates to observe the spacetime events, which in turn is not what he actually want to study and so on. Sometimes I have the feeling that asking for tests of concepts is - when you go into specifics - like using sophistry to interact with sophistry. Give me a test, or the idea is less useful (and most likely wrong).

Apr 06, 2019
"gravity does. Because it has no countervailing force".

The easiest way to derive that a gravity field has only a positive putative charge particle is perhaps to note that you cannot observe dipole radiation as you do in electromagnetic fields; these observatories see quadrupole waves.

Sometimes you can see the notion that since gravity extends indefinitely it is not shielded by opposite charges (in a field approximation), or that since spacetime can only curve it has no counter force. (But placing an equally curving mass close and put yourself on the valley in between let you minimize the gradient force, in an analogous way to how free fall around Earth at some 60 % surface gravity at ISS distances is taken as "microgravity".)

Or do you have some easier way of putting it to the test?

Also, missing link to Quanta quote in my first comment: https://www.quant...0180430/ .

Apr 06, 2019
But correct predictions do.


I predict that if you do a Native American rain dance every day, it will work every day it rains.

Apr 06, 2019
"These mysterious compact objects would therefore have a surface that would reflect gravitational waves."

Egad, gentlemen: Cavorite!

Apr 06, 2019
But correct predictions do.


I predict that if you do a Native American rain dance every day, it will work every day it rains.
So basically you think AGNs turn on and off daily.

Teh stoopit, it burnz.

Apr 06, 2019
@torbjorn, that means that to nullify gravity on Earth's surface, you need another Earth the same distance above you as the Earth is below you.

Or, you can work out the mass for something less, at less distance... and you will find it's implausible to say the least. Nobody's bringing a black hole close enough to the surface of the Earth to do that unless they're utterly insane.

Apr 07, 2019
I predict that if you do a Native American rain dance every day, it will work every day it rains.

Most succinct example for demonstrating that correlation is not causation. I'll grab that one for future reference.
Thanks.

Apr 08, 2019
"They radiate out across the universe at the speed of light, passing through almost everything in their path."
Shouldn't they pass through _everything_ in their path?

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