What did you always wonder about #BlackHoles? Something that you always wanted to ask an astronomer working on them?
Collecting questions for a reason, maybe even answering them in the comments (or at a later point).
Dr. Victoria Grinberg reshared this.
Joe
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Joe • • •Joe
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Joe • • •Joe
in reply to Dr. Victoria Grinberg • • •Expertenkommision Cyberunfall
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Expertenkommision Cyberunfall • • •Expertenkommision Cyberunfall
in reply to Dr. Victoria Grinberg • • •So, within the singularity, is there something similar to our concept of time?
And how long would a person on earth need to wait for an “in singularity breewed three minute tea”?
Dr. Victoria Grinberg
in reply to Expertenkommision Cyberunfall • • •Peter Jakobs ⛵
in reply to Expertenkommision Cyberunfall • • •Dr. Victoria Grinberg
in reply to Peter Jakobs ⛵ • • •Peter Jakobs ⛵
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Peter Jakobs ⛵ • • •Nicolas Dufour
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Nicolas Dufour • • •Nicolas Dufour
in reply to Dr. Victoria Grinberg • • •It seems described as "quantum hair".
Ah yes, the no-hair theorem must be the one. Sorry, I'm definitively not a specialist in this domain.
Dr. Victoria Grinberg
in reply to Nicolas Dufour • • •Mikael Lundin 🍀🥦♻️
in reply to Dr. Victoria Grinberg • • •Jose Sabater
in reply to Mikael Lundin 🍀🥦♻️ • • •Dr. Victoria Grinberg
in reply to Jose Sabater • • •Dr. Victoria Grinberg
in reply to Mikael Lundin 🍀🥦♻️ • • •Excellent question! That's one of the things that I find people struggle to get their way around in theory of relativity - that time is not something absolute! To be honest, this is also not something I can easily imagine, because it's so outside of my experience even though i could (after some refreshing of the maths) calculate it.
To an observer outside, the time seems to stand still. But to the person falling in, it will actually keep going at a normal pace!
Andreas
in reply to Dr. Victoria Grinberg • • •There's a "surface" (event horizon) below light cannot escape.
There's the (mathematically) construct of a singularity in the middle.
But what's between those?
And what the frick is this singularity?! 😵💫
Dr. Victoria Grinberg
in reply to Andreas • • •@ePD5qRxX the actual physical representation are the formulae of the general relativity 😀
I think our failure to imagine clearly what this means except by using images and metaphors from our everyday life just shows that our brains are not very well equipped imaging things that are not within our own experience. We have very clear expectations how space should behave ...
Bart Smit / ⲁⲗⲍⲓⲙⲟⲛ
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Bart Smit / ⲁⲗⲍⲓⲙⲟⲛ • • •@alzimon A really small part! For example, the mass of the supermassive black hole in our own Galaxy is 4.3 million solar masses, but the mass of the Milky Way are several hundred billion solar masses. Even if we count all the stellar mass black hole in the Milky Way additionally, it will still be a very small part. Similar consideration apply to other Galaxies.
It will grow over time as more stars die and become stellar black holes and as supermassive black holes grow but sloooooowly.
Bart Smit / ⲁⲗⲍⲓⲙⲟⲛ
in reply to Dr. Victoria Grinberg • • •Henrik Schönemann
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Henrik Schönemann • • •Henrik Schönemann
in reply to Dr. Victoria Grinberg • • •I should have specified: "... any *other* metaphors"^^
And yes, I agree with your assessment re metaphors as a whole
(spoken with a background in literature studies)
Tarnport
in reply to Henrik Schönemann • • •Dr. Victoria Grinberg
in reply to Tarnport • • •Ives
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Ives • • •Ives
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Ives • • •It's still nothing getting out, as mind-boggling it sounds; but this is where our simple understanding breaks down because this is so far outside of how world works in our everyday experience!
Ives
in reply to Dr. Victoria Grinberg • • •Sarah Brown
in reply to Dr. Victoria Grinberg • •like this
❄️ Dr. Ferrous ❄️, Jonathan Schofield, Tommaths (he/him) and Dr. Victoria Grinberg like this.
p
in reply to Sarah Brown • • •@goatsarah
Do Black Holes have Singularities?
arXiv.orgTommaths (he/him)
in reply to Sarah Brown • • •I was trying to work out how to word this idea; I think you've done a really good job of it!
Sarah Brown likes this.
Dr. Victoria Grinberg
in reply to Tommaths (he/him) • • •@TeaKayB @goatsarah I've answered the question here: mastodon.social/@vicgrinberg/1…
Dr. Victoria Grinberg
2025-02-12 08:30:25
Dr. Victoria Grinberg
in reply to Sarah Brown • • •Sarah Brown likes this.
kzurell
in reply to Dr. Victoria Grinberg • • •Seem to recall there are equations for rotating black holes, and equations for non-rotating black holes.
Are there equations for "black holes that don't rotate very much at all, slow as molasses but not completely still"?
...or, alternatively...
Is there such a thing as "non-rotating" at all anywhere in any reference frame? Is "non-rotating" just a simplification that doesn't really exist?
Dr. Victoria Grinberg
in reply to kzurell • • •B Thoreau
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to B Thoreau • • •B Thoreau
in reply to Dr. Victoria Grinberg • • •Yes, NASA released a recording, adjusted to the human range of hearing. There are some other videos that use this recording and explain these cause ripples.
youtu.be/NWBkZ3bMSV0?si=6mxznz…
What do black holes sound like? NASA releases recording of black hole in distant galaxy
YouTubeB Thoreau
in reply to B Thoreau • • •Dr. Victoria Grinberg
in reply to B Thoreau • • •dana
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to dana • • •Eye
in reply to Dr. Victoria Grinberg • • •@dana
I had to bookmark this reply. I'm struggling to comprehend the potential of a black hole so tiny! I love it 🤯
dana
in reply to Dr. Victoria Grinberg • • •So, black holes are entirely a concept of relativity theory, confirmed by astrophysical observation? But there is no quantum mechanical theory of black holes? That's very interesting.
#astrophysics
Dr. Victoria Grinberg
in reply to dana • • •Frank van Lankvelt
in reply to Dr. Victoria Grinberg • • •Brent Guernsey, Artrocity Studio
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Brent Guernsey, Artrocity Studio • • •Trebor Resro
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Trebor Resro • • •Stylus
in reply to Dr. Victoria Grinberg • • •"when" is a black hole fully formed, from the perspective of a distant observer? Suppose we see a supernova, can we say how much later the remnant becomes a black hole? (In a general order of magnitude) Naive explanations of relativistic time dilation seem to indicate "forever or just short of it". Is there something easy to explain about where this simplification becomes misleading? E.g. Wikipedia says
> To a distant observer, clocks near a black hole would appear to tick more slowly than those farther away from the black hole. Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow as it approaches the event horizon, taking an infinite amount of time to reach it.
Dr. Victoria Grinberg
in reply to Stylus • • •@stylus this is a bit mind-boggling because this is totally outside of our everyday experience. In a way, to the outside observer, there is never a fully formed black hole. But at the same time there is no difference between "a fully formed" black hole and an almost formed one to the outside observer.
Things like this a somewhat hard to grasp (but well described in maths), because it's so far outside of our experience of how the world and spacetime works ...
Andre
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Andre • • •@ComPod Gaia BH1 is about 1500 years away and is the clostest stellar mass black hole currently known en.wikipedia.org/wiki/Gaia_BH1
Sag A* is the closest supermassive one.
binary system in the constellation Ophiuchus
Contributors to Wikimedia projects (Wikimedia Foundation, Inc.)Virginicus
in reply to Andre • • •Andre
in reply to Virginicus • • •Dr. Victoria Grinberg
in reply to Andre • • •@ComPod @Virginicus oh no, we have known of black holes long before!
There is indeed no list of known black holes, but this is mostly because there are so many. There are tons and tons of AGN - active galactic nuclei - so accreting black holes in centers of galaxies known. The first eRosita catalog alone contains over 700 000 black holes aip.de/en/news/erosita_dr1/, but we known a lot even before and long before LIGO.
There are also several handful of confirmed stellar mass black holes.
First eROSITA sky-survey data release presents the largest ever catalogue of cosmis X-ray sources
www.aip.deSoldier of FORTRAN
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Soldier of FORTRAN • • •Soldier of FORTRAN
in reply to Dr. Victoria Grinberg • • •Willem Van den Ende - Writing
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Willem Van den Ende - Writing • • •lhp
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to lhp • • •jiawen
in reply to Dr. Victoria Grinberg • • •Wyatt H Knott
in reply to Dr. Victoria Grinberg • • •Are black holes the source of a Big Bang in another dimension?
I mean I know in theory that all the mass is concentrated to a point, and supposedly it's all still there making the black hole, but it feels like the mass has to go somewhere.
Dr. Victoria Grinberg
in reply to Wyatt H Knott • • •Wyatt H Knott
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Wyatt H Knott • • •Misja van Laatum
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Misja van Laatum • • •@misjavanlaatum spacetime! Or if something is in the process of falling into the black hole, than the material.
Keep in mind that the event horizon is not like the surface of a planet, it's more an imaginary line along the floor that people are not allowed to step over. It's not like there is suddenly a walk of cake on the other side. Does this comparison help?
Misja van Laatum
in reply to Dr. Victoria Grinberg • • •Bill
in reply to Dr. Victoria Grinberg • • •David Quintero
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
Unknown parent • • •nadja
in reply to Dr. Victoria Grinberg • • •Fedo ¶
in reply to Dr. Victoria Grinberg • • •Dr. Victoria Grinberg
in reply to Fedo ¶ • • •@fdrc_ff what a cool question! both are measuring different wavelength of gravitational waves - Earth-bound GW detector you are limited by the size of the Earth, space based you can go larger and measure GW from merging supermassive black holes (LISA) and from primordial gravity fluctuations (PTA).
LISA was adopted to be built by ESA in 2024 - esa.int/Science_Exploration/Sp…
For PTA, there are multiple collaborations observing pulsar for such studies eg these folks here epta.eu.org/
LISA factsheet
www.esa.intLocalJoost 🥽
in reply to Dr. Victoria Grinberg • • •j5v
in reply to Dr. Victoria Grinberg • • •Are you hopeful for an underlying mathematical basis that satisfies physics 'inside' and outside of black holes? Without converting between systems of algebra - a generalization?
Related: do we have biases in our understanding or perspective that are a barrier to that? (a philosophical and non-political question!)
Tony Masiello ☮
in reply to Dr. Victoria Grinberg • • •Antonio Vieiro
in reply to Dr. Victoria Grinberg • • •Photons can get trapped in circular orbits around a black hole in the so called "photon sphere", right?
So the longer a black hole exists, the more the photons trapped (the more the energy in the photon sphere).
1. Will I get "fried" by all these photons before reaching the event horizon?
2. Can we measure the amount of energy trapped in these photon spheres?
3. Can this amount of energy be used to measure the age of a black hole?
en.wikipedia.org/wiki/Photon_s…
Photon sphere - Wikipedia
Contributors to Wikimedia projects (Wikimedia Foundation, Inc.)Dr. Victoria Grinberg
Unknown parent • • •Much small, closer to Planck scale, things get tricky because we need to combine general relativity and quantum mechanics and that's one big question of modern physics how to do this...
Daleus, Curmudgeon-at-Large
in reply to Dr. Victoria Grinberg • • •Black Hole knowledge seems to be rising rapidly these days, yet they remain pretty mysterious.
Questions:
Do you think human technology will ever get to the point where we could travel into one safely and possibly arrive on the other side?
If yes, how long do you think it might take to get to that point?
What is your best guess of what will be on the other "side"?
Dr. Victoria Grinberg
in reply to Daleus, Curmudgeon-at-Large • • •Daleus, Curmudgeon-at-Large
in reply to Dr. Victoria Grinberg • • •I get what you're saying.
Are you sure we have a complete knowledge of physics at this moment?
Could developments and new insights in the future, make it possible?
Might that be improbable, but not impossible?
Dr. Victoria Grinberg
in reply to Daleus, Curmudgeon-at-Large • • •Daleus, Curmudgeon-at-Large
in reply to Dr. Victoria Grinberg • • •You realize you're wrecking my dreams of the future, as portrayed in the voluminous history of Science Fiction literature!
Oh well, Science Fact reigns supreme!
Perchance, we'll find some other way to flit around the universe than stupid black holes.
<disappointedly scuffs toes in the loose dirt>.
Dr. Victoria Grinberg
in reply to Daleus, Curmudgeon-at-Large • • •Roquette ⁂
in reply to Dr. Victoria Grinberg • • •Thomas
in reply to Dr. Victoria Grinberg • • •Might there be black holes of black matter?
#BlackHoles #VicisAstro
Adam Yates
in reply to Dr. Victoria Grinberg • • •Duncan Murray
in reply to Dr. Victoria Grinberg • • •xanna
in reply to Dr. Victoria Grinberg • • •Tommaths (he/him)
in reply to xanna • • •Nice.
Jonathan T
in reply to Dr. Victoria Grinberg • • •pantos
in reply to Dr. Victoria Grinberg • • •How does Hawking radiation work? If a matter/antimatter particle pair is created at the event horizon and one falls in, do they cancel out inside the BH? Also, the photon from which they are created should come from outside, so why does the BH lose mass?
Can a BH become smaller than the planck length? Can things still "fall in"? And what happens if it becomes smaller in only one direction? E.g. by moving close to lightspeed towards it? Would we see an infinitely thin "BH disk"?
MartinaSausG
in reply to Dr. Victoria Grinberg • • •Jeff Spencer
in reply to Dr. Victoria Grinberg • • •Peter Hartley
in reply to Dr. Victoria Grinberg • • •Tommaths (he/him)
in reply to Peter Hartley • • •@TalesFromTheArmchair
Black holes form when something provides enough energy to overcome the pressure that stops things collapsing in on themselves. One of the things that can provide enough energy is gravity, if you have enough of it, and that gravity comes from getting an enormous amount of matter together in one place.
Another way of overcoming that pressure is by smacking things together _really_ hard. If you could smack two peas together hard enough that the matter that made those peas ended up inside their own event horizon, you'd have made a tiny black hole.
There are some very high-energy things whizzing about the universe. If they hit the right things in the right way, they could form tiny black holes.
Regarding the not popping back out again: once that stuff is inside its own event horizon, there's no popping out: nothing crosses the boundary the other way.
Dr. Victoria Grinberg
in reply to Tommaths (he/him) • • •Tommaths (he/him)
in reply to Dr. Victoria Grinberg • • •@TalesFromTheArmchair
Thanks! So lots of mass _is_ the only feasible route for black hole formation?
Dr. Victoria Grinberg
in reply to Tommaths (he/him) • • •Tommaths (he/him)
in reply to Dr. Victoria Grinberg • • •Cool. Are the energies required feasible from, say, a future particle accelerator? Or is that asking too much of human technology?
Dr. Victoria Grinberg
in reply to Tommaths (he/him) • • •Tommaths (he/him)
in reply to Dr. Victoria Grinberg • • •Cool, thanks!
blan©k.
in reply to Dr. Victoria Grinberg • • •@Franziska_Naja
Dr. Victoria Grinberg
in reply to blan©k. • • •But I can tell a bit about the relationship: black holes have 3 properties - mass, spin and charge. Stellar mass black holes get all three mostly from their progenitor stars. So if we know how many black holes of e.g. different masses there are we can say something about what kind of stars made them, same if we look at black hole spin and try to derive how their progenitors rotated.
Dr. Victoria Grinberg
Unknown parent • • •Dr. Victoria Grinberg
Unknown parent • • •Henrik Schönemann
Unknown parent • • •What other language/phrasing/metaphors can we use to talk about it?
@ NovaNaturalist🇨🇦🇩🇰🇬🇱🇵🇦🇲🇽 FBPE
in reply to Dr. Victoria Grinberg • • •how small can a black hole be?
...and how large?
Dr. Victoria Grinberg
in reply to @ NovaNaturalist🇨🇦🇩🇰🇬🇱🇵🇦🇲🇽 FBPE • • •@NovaNaturalist great question! this answer may be helpful: mastodon.social/@vicgrinberg/1…
Dr. Victoria Grinberg
2025-02-09 13:06:28
Tane Piper ⁂
in reply to Dr. Victoria Grinberg • • •simonbp
in reply to Dr. Victoria Grinberg • • •