INTO THE BLACK HOLE....

[jayne lee wilson]

... I found How to see a Black Hole (BBC4) moving as well as fascinating because it showed the "human-made story" of how such images come to be created; the extraordinary effort of building superstructure and software and the physical and mathematical co-ordination of it all; the challenges to or confirmations of, the very foundational theories of Einsteinian modern physics. ... it is about scientific creativity and ingenuity, a close relative of artistic creation....

So the images appear, quite rightly, near the end, as the triumphant result - which is yet another beginning....

[LMcD]

So it's Mark Frank-Oiz then. More like Frank Oik, if you were to ask me. He's the epitome of Harry Enfield's Tory Boy.

Mark is Franco (anagram)

[Serial_Apologist]

... I found How to see a Black Hole (BBC4) moving as well as fascinating because it showed the "human-made story" of how such images come to be created; the extraordinary effort of building superstructure and software and the physical and mathematical co-ordination of it all; the challenges to or confirmations of, the very foundational theories of Einsteinian modern physics. ... it is about scientific creativity and ingenuity, a close relative of artistic creation....

So the images appear, quite rightly, near the end, as the triumphant result - which is yet another beginning....

Apparently if one fell into a black hole, it would be for a considerable stretch...

[jayne lee wilson]

Reading about this today, it seems the "event horizon' is not the black hole itself, but the mysterious forces within it where the known laws of physics may collapse... which we may never see or truly understand, unless we visit it..(job for another Voyager - let the robots do what they're better at..).. I couldn't help thinking about Bowman in 2001: A Space Odyssey, as the space-pod falls into the black monolith, and what happened after that...

[vinteuil]

Reading about this today, it seems the "event horizon' is not the black hole itself, but the mysterious forces within it where the known laws of physics may collapse... which we may never see or truly understand, unless we visit it.....

... not recommended :

https://en.wikipedia.org/wiki/Spaghettification

.

[jayne lee wilson]

... not recommended :

https://en.wikipedia.org/wiki/Spaghettification

.

As I said, just get those revolutionary robots in there... you'll have to be a bit innovative in what you build them from though...

[LezLee]

Do you all know about the NASA Picture of the Day? https://apod.nasa.gov/apod/astropix.html

[Dave2002]

Physics, as we know it, is pretty weird in the vicinity of a black hole. The link to spaghettification was interesting.

However, two things occur to me.

1. Is it possible to orbit a black hole? Probably yes - though it would be very critical. In the event that other matter was "sucked" in to the black hole, the attraction into the black hole would increase, and the orbiting object would then inevitably fall in. The shape of the orbit would also play a part - see 2. Black holes colliding would seem to indicate the possibility of orbits round black holes. These have been observed in recent years I think.

2. Is it possible for a very energetic body to skim across the edges of a black hole? This would be similar to a comet coming very close to a body such as the sun, then moving much further out. However a comet is in orbit, so referring back to 1 - an object which was already in orbit round a black hole would still eventually fall in. In order to avoid this, an object would have to be moving so fast that it would actually be able to escape gravitational influences. In the last year or so, one fairly large object has been observed passing through the solar system, and will presumably travel on and into outer space. By analogy that might just be possible for black holes.

I don't know the answer to 2 - whether it's possible for very highly energetic objects to pass across the boundaries of a black hole and still escape.

PS: I guess it's essential that any rapidly moving object would have to be moving faster than the speed of light - which we have thought impossible. Nevertheless, with physics weirdness now - dark matter and dark energy to mention two very much unexplained phenomena, it may still be possible.

[Bryn]

. . . Is it possible to orbit a black hole? Probably yes - though it would be very critical. In the event that other matter was "sucked" in to the black hole, the attraction into the black hole would increase, and the orbiting object would then inevitably fall in. The shape of the orbit would also play a part . . .

Your use of the word "event" in this context put me in mind of one of my favourite DNA concepts, that of the "shoe event horizon" which the

[LeMartinPecheur]

Physics, as we know it, is pretty weird in the vicinity of a black hole. The link to spaghettification was interesting.

However, two things occur to me.

1. Is it possible to orbit a black hole? Probably yes - though it would be very critical. In the event that other matter was "sucked" in to the black hole, the attraction into the black hole would increase, and the orbiting object would then inevitably fall in. The shape of the orbit would also play a part - see 2. Black holes colliding would seem to indicate the possibility of orbits round black holes. These have been observed in recent years I think.

If as seems to be the case the centre of our galaxy, a.k.a. the Milky Way, is a black hole, all of us on the message board and everything else in our galaxy are currently in orbit around a black hole! The same goes for everything we see of the vast M87 galaxy and its millions of stars. Remember that most of space in our galaxy is empty, and how many light years we are from our nearest star, 4.24ly or about 25 trillion (25 million million) miles and there are about a hundred trillion stars in our galaxy. Between galaxies space is even more empty and inter-galactic distances get far, far bigger. Our nearest neighbour, the Andromeda galaxy, is 2.5 million light years away (~10 million million million miles), and that is close!

2. Is it possible for a very energetic body to skim across the edges of a black hole? This would be similar to a comet coming very close to a body such as the sun, then moving much further out. However a comet is in orbit, so referring back to 1 - an object which was already in orbit round a black hole would still eventually fall in. In order to avoid this, an object would have to be moving so fast that it would actually be able to escape gravitational influences. In the last year or so, one fairly large object has been observed passing through the solar system, and will presumably travel on and into outer space. By analogy that might just be possible for black holes.

I don't know the answer to 2 - whether it's possible for very highly energetic objects to pass across the boundaries of a black hole and still escape.

PS: I guess it's essential that any rapidly moving object would have to be moving faster than the speed of light - which we have thought impossible. Nevertheless, with physics weirdness now - dark matter and dark energy to mention two very much unexplained phenomena, it may still be possible.

One side of a line (the 'event horizon') on the edge of a black hole and you're inescapably drawn in. Just a little further out and capture isn't automatic but you'd need to be travelling at enormous speed, close to light speed, and therefore burning huge amounts of energy, to escape.

One interesting thing dreamt up by the late Stephen Hawking is that black hole can evaporate if left long enough and not 'fed'! Right on the boundary between 'escape possible' and 'escape impossible', some matter (pretty weird matter in a high energy state) could discharge a high energy particle (some small sub-atomic particle) firing outward that would escape while its emitter would, by conservation of momentum I think, be thrown faster back towards the centre of the BH. But this trick is only a possibility for subatomic particles - no escape from spaghettification for astronauts!

This link explains the evaporation, and a lot else about black holes, a lot better than I did https://medium.com/starts-with-a-ban...e-5463dbda6832

[BBMmk2]

This is absolutely fantastic news. I saw them at a press conference about it. Incredible.

[Dave2002]

One interesting thing dreamt up by the late Stephen Hawking is that black hole can evaporate if left long enough and not 'fed'! Right on the boundary between 'escape possible' and 'escape impossible', some matter (pretty weird matter in a high energy state) could discharge a high energy particle (some small sub-atomic particle) firing outward that would escape while its emitter would, by conservation of momentum I think, be thrown faster back towards the centre of the BH. But this trick is only a possibility for subatomic particles - no escape from spaghettification for astronauts!

This link explains the evaporation, and a lot else about black holes, a lot better than I did https://medium.com/starts-with-a-ban...e-5463dbda6832

It doesn't look as though anyone has "seen" orbiting black holes yet, but the effects of orbiting black holes which collided has been observed by the detection of gravity waves.

When galaxies collide they mostly just pass through each other, but there is the possibility that black holes near the centre of each will orbit and collide.

More details here - https://en.wikipedia.org/wiki/Binary_black_hole