- 2945 - BLACKHOLES - that can not be explained? In October, 2020, the LIGO/Virgo collaboration published its latest batch of data, bringing the running total to 47 blackhole mergers, including two more that seem to feature at least one blackhole in the mass gap. And, a new gravitational-wave observatory in Japan, KAGRA, ran for two months earlier this year.
- Why do we press harder on a remote control when we know the batteries are getting weak?
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- Why do banks charge a fee on "insufficient funds" when they know there is not enough money?
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- Why do they use sterilized needles for death by lethal injection?
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- Why doesn't Tarzan have a beard?
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- Why does Superman stop bullets with his chest, but ducks when you throw a revolver at him?
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- Why do Kamikaze pilots wear helmets?
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- Whose idea was it to put an "S" in the word "lisp"?
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- Is there ever a day that mattresses are not on sale?
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- Why do people constantly return to the refrigerator with hopes that something new to eat will have materialized?
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- Why is it that no plastic bag will open from the end you first try?
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- How do those dead bugs get into those enclosed light fixtures on the front porch?
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- Why is it that whenever you attempt to catch something that's falling off the table you always manage to knock something else over?
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- In winter why do we try to keep the house as warm as it was in summer when we complained about the heat?
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- How come you never hear father-in-law jokes?
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- If at first you don't succeed, then don't take up sky diving!
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- My doctor finally found out what I had , and took it.
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- My doctor told me I had low blood pressure. He gave me his bill and fixed it.
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- A Specialist is a doctor with a smaller practice and a bigger house.
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- My doctor told me I had a body of a twenty year old ………………… Chevy.
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- I complained to my doctor about groin pains.
He said it was strained muscles and asked me how often I had sex.
Monday, Wednesday and Friday.
Well, I recommend you cut out the Wednesdays.
No, I can’t do that, it’s the only night I’m home.
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------------------ 2932 - BLACKHOLES - that can not be explained?
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- On May 21, 2019, a ripple in spacetime alerted scientists to what they thought was an impossible event It was a collision between two black holes that should not have existed.
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- The LIGO and Virgo gravitational wave observatories had witnessed over a dozen black-hole collisions, but this merger was different. Both blackholes were situated in the “mass gap,” a range of masses that, for black holes, should be forbidden.
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- Black holes form when stars collapse at the end of their lives. But ,they must be big enough stars; the smallest ones become white dwarfs or neutron stars instead of collapsing all the way into a backhole.
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- While a star lives, the nuclear reactions and radiation in its interior provide an outward pressure that balances the inward pull of its gravity. When that balance is lost, a core-collapse supernova can leave behind a blackhole with at most 50 times the mass of the Sun.
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- At least, that’s what happens to medium-sized stars. In the cores of larger stars, high densities and temperatures trigger the creation of “electron-positron pairs“, resulting in a more powerful explosion called a “pair-instability supernova“.
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- These electron-positron pairs provide gravity but no pressure, so the star starts to collapse prematurely. The star becomes so hot that you can start to do nuclear reactions with the oxygen in the core. Then because the oxygen burns, you have this immediate explosion, and you’re left with nothing. Everything evaporates. No remnant, no blackhole.
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- The most massive stars meet yet another end; they can bypass the explosion to collapse into a blackhole weighing at least 120 solar masses. So a black hole can form with a mass less than about 50 or more than 120 times that of the sun, but no known mechanism allows a dying star to become a blackhole with a mass in the gap between.
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- Yet. the gravitational waves spotted by LIGO and Virgo revealed black holes weighing 66 and 85 solar masses. What’s with that?
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- Have we estimated the masses correctly. This mass can’t be in the gap. There’s no such thing as a blackhole in the gap. But, the calculations held up. What then?
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- The discovery has sparked a flurry of proposed explanations. Some are purely astrophysical: Maybe the two black holes that merged were in turn the children of prior mergers, or perhaps they were born below the mass gap and grew by gobbling up nearby objects.
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- Some scientists question the LIGO/Virgo analysis, proposing instead that the larger blackhole sits above the gap and the smaller below it.
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- Another scenario explored for a look for an explanation at the tiniest scale. Maybe there is particle physics theory beyond the Standard Model.
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- Particles that are candidates for dark matter, that mysterious substance that forms 85% of the universe’s matter, could also affect the inner workings of stars. Photons could occasionally transform into “hidden photons” that interact very weakly with ordinary matter and have a tiny but nonzero mass.
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- While ordinary photons are continually absorbed and reemitted within a star, hidden photons would escape unscathed, carrying away some of the star’s energy. This extra loss of energy would set off a whole new unexplored condition.
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- The star would burn through its helium faster, which simulations suggest would give the star less oxygen in its old age. Having less oxygen, the star would need a larger mass to cross the threshold for a pair-instability supernova. Therefore, blackholes heavier than 50 solar masses could form.
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- Other hypothesized particles called axions would have a similar effect. The presence of weakly interacting particles would affect more than just the final phase of a star’s life. As a result, scientists can use astrophysical observations to place limits on the properties of these theoretical particles.
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- Undiscovered particles cannot be ruled out as the reason we see these seemingly impossible black holes. It’s tantalizing that through simulating the evolution of these early stars, you can learn about the tiniest particles that have been proposed. We’re using very large black holes to study very small particles
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- Another proposal hinges not on extra particles, but on extra spatial dimensions. Physicists have long speculated that in addition to the three dimensions we see, more dimensions could lie curled up at the subatomic scale. If these dimensions are large enough, energy from the interiors of stars could leak into them.
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- In contrast to hidden particles carrying energy away from the star, the extra dimensions would hide energy within the star, but the result would be the same: Both the lower and upper bounds of the mass gap would increase.
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- A third possibility, “modified gravity“, would overturn an assumption held by both Isaac Newton and Albert Einstein. The inherent strength of gravity, instead of being constant throughout the entire universe, could depend on the cosmic environment.
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- So different regions in space would have different mass gaps. In regions where gravity is stronger, both pair-instability supernovae and the shortcut taken by the largest stars would kick in at lower masses, putting the mysterious blackholes above the local mass gap rather than within it.
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- All these beyond-the-Standard-Model ideas have to be disentangled from the fundamental physics the astrophysics we understand today.
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- Oyctober, 2020, the running total came to 47 blackhole mergers, including two more that seem to feature at least one blackhole in the mass gap. And, a new gravitational-wave observatory in Japan, KAGRA, ran for two months earlier this year.
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- We’re in the middle of the LIGO discovery bump increasing by orders of magnitude. Researchers could spot thousands of blackhole mergers in the coming decade.
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- From new particles to new ideas about gravity, all of this extra science is coming for free, just because we decided to listen to the universe in a way that we’ve never observed it before.
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December 20, 2020 BLACKHOLES - that can not be explained? 2945
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