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 AndrewGPaul wrote:
Actually, you could cross the event horizon of this black hole easily. At a radius of 80 AU (twice the orbital radius of Pluto round the Sun), the tidal forces will be irrelevant, so you can just fly through without noticing - until you try to get out ...

There are mathematical solutions of the equations of General Relativity that appear to allow an object to travel into its own past, but they're all rather unusual (for example, they aren't compatible with the universe as we observe it). If I'm understanding correctly, the interior of a rotating black hole is one of those solutions, but ultimately it doesn't matter since you won't be able to get back out again to tell anyone. Or, it's all just a mathematical artefact and it isn't really like that. Regardless, it's all totally theoretical and there's no way for us to make use of the theory with any forseeable technology. Makes for a good sci fi novel and lests the author throw around terms like "Kerr Metric", "closed timelike curves" and suchlike to sound cool, that's all.

The numerical solutions for the Kerr metric (spinning neutral black hole) results in two event horizons. The first solution inner event horizon is the same as the schwarzchild metric, this is the literal point of no return. The outer event horizon creates a region known as the ergosphere. This is the volume between the inner and outer event horizons. This outer event horizon, however, is different to the inner event horizon. Rather than being a point of no return, it actually signifies a point at which, once you go past it, you must begin to rotate in the same direction as the black hole.

This allows for the Penrose process, a means of harnessing power from black holes by draining their angular momentum. In short: send object on trajectory through ergosphere, it gains angular momentum from black hole, convert angular momentum to energy.

 AndrewGPaul wrote:
And as has been mentioned previously, exactly that effect has been measured on Earth; sufficiently accurate clocks sent up in aircraft will measure less elapsed time than ones left on the ground.

Yup. If we did not account for this with the GPS satellites, they would be losing ~10km of accuracy a day.

Presumably if you do that enough the black hole stops spinning and you end up with a Schwarzchild black hole?

Now there's a thought for an interstellar war ... One side uses Kerr metric black holes to travel in time (mumblemumble magic technology to get back out again ...), the other side fires stuff at the black holes to stop them spinning.

 Stormatious wrote:

 A Town Called Malus wrote:

 Stormatious wrote:


It seems you are explaining what i was already trying to say which is yes the further some thing away the longer it takes to get there etc, but i dont see how what you are saying explains why i am wrong about a galaxy being a mass... inside the unverise which HAS mass.?

It's not about taking longer to get there. It is about the time between events. If you are 30 light years away from a the person flashing the light at you, it doesn't matter if you are in a well or not, it will take 30 years for the light to reach you. The time between the flashes, however, will change depending on if you are inside a gravity well or not.

Ok ill think about this further.

Thank you.

Can I suggest that perhaps instead of just thinking about it, doing a substantial amount of reading on the subject may be better? Relativity is a bit of a mind-bender until you get the core concepts straight. Wikipedia is a good place to start, though there are plenty of other sources of information that explain relativity in fairly straight forward fashion.

For all the memes about nobody finishing A Brief History of Time, I found it pretty straightforward.

The dodgy ebook version I had was less so, since the illustrations were mssing.

 AndrewGPaul wrote:
Presumably if you do that enough the black hole stops spinning and you end up with a Schwarzchild black hole?

Yup. The theoretical maximum amount of energy that can be extracted is around 29% of the black holes original mass, which is a huge amount of energy.


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 AndrewGPaul wrote:
For all the memes about nobody finishing A Brief History of Time, I found it pretty straightforward.

The dodgy ebook version I had was less so, since the illustrations were mssing.

Oh wow, relativity without illustrations sounds pretty horrible

I recommend Why Does E=MC² by Brian Cox and Jeff Forshaw for anyone interested in relativity but not particularly confident in their maths/science ability. It does a great job breaking it all down into an easily understandable concept (well, as close as relativity gets to that). It also does a nice job of showing how easy it can be to derive the equations used in special relativity. You can literally get the lorentz factor for special relativity time dilation, length contraction, velocity transforms etc. using nothing more complicated than pythagoras' theorem, which is pretty cool. It only has a bit at the end about general relativity (much harder to derive anything mathematically for general relativity due to it's usage of differential calculus and tensors) but it has a nice thought experiment to demonstrate the point.

cody.d. wrote:

Unfortunately I have to make this comment, and I might get dinged for it, but, here goes...

This achievement has shown me just how uneducated, and poorly reasoned our society has become. Just reading through some of the comments today, listening to the media coverage has made my ears and eyes bleed. It's amazing how out of touch the public is with very simple science.

I'm actually curious as to what you mean? Like, you obviously seem to have some genuine knowledge/interest in the subject. Do you mean the "hole" part of the name confusing people? Much like how darkmatter isn't actually just stuff that's black but a sort of catchall term for a spectrum of stuff in the galaxy we don't quite understand yet. But then you see it in sci-fi as some sort of weapon material.

The general public reaction to this in news article comment sections has been terrible. People can't grasp why the image is so pixelated, or what the process was in recording this image. I've seen some of the most bat guano crazy statements about this out there, from people claiming it to be fake, to people claiming that it is a conspiracy. A local radio program yesterday (where my parents live) had a Scientist from UMKC on to talk about the discovery. After the segment was over, the two hosts began to make statements about the scientists "common sense." I'm not sure what the term for that is, but it's when a person feels intimidated by another, and so they try and belittle them for the thing that makes them feel inferior. It seems to me, as someone who has been involved in this field for many years, that each year that passes gets worse and worse for general science knowledge in the public. If you go to any NASA site that allows comments, 70% of the comments will be nonsensical, insane rantings, or cries of conspiracy. Probably because the internet has given people of lower ability spaces to congregate and share their ideas.

Another story I can share involves a Doctor my mother works with. I was speaking with him about another Astronomical topic last time I was home. I was amazed that someone who has set through college physics, couldn't grasp a simple concept (interferometry). Not even on a mathematical level, but on a conceptual level. It was truly a disheartening experience.

Why the feth would anyone fake a pixellated image of a black hole? Aren't there better things to fake?

 Kilkrazy wrote:
Why the feth would anyone fake a pixellated image of a black hole? Aren't there better things to fake?

If they fake it pixelated then it’s more believable

 A Town Called Malus wrote:


Oh wow, relativity without illustrations sounds pretty horrible .

Luckily I'd read it before, in a proper edition, and the remnants of my physics degree are still here and there in my brain. Actually, if I'd been reading a book about relativity that had been deliberately written with no illustrations, it wouldn't have been so bad. But this had bits like "And as shown in the diagram above ..." with no diagram.

And yes, the celebration of ignorance in the media is depressing. There's no shame in not knowing about relativity or black holes, or not understanding why the discovery might be important; it's been a couple of centuries since there was sufficiently little science that you could know about all of it. But being actively proud that you don't know something? Thinking that you're better than someone because they know/understand/get excited about something you don't? I can't be bothered with that sort of scum.

 Kilkrazy wrote:
Why the feth would anyone fake a pixellated image of a black hole? Aren't there better things to fake?

Unfortunately, the internet has become a place that not only allows, but encourages delusional people to congregate and spread their ideas. From Anti-Vaccination groups, to Flat Earthers, Moon Conspirators, and "New World Order" believers. With mental illness on the rise, it's only going to get worse.

 Kilkrazy wrote:
Why the feth would anyone fake a pixellated image of a black hole? Aren't there better things to fake?

You vastly underestimate the conspiracy industry. I know one or two people who are into that. Its legitimately cray cray.

 AndrewGPaul wrote:
...it's been a couple of centuries since there was sufficiently little science that you could know about all of it.

Only roughly 150 years if you exclude "catalogue sciences" like archeology/history of various flavours. Many of key modern broad fields of empiric science did not even exist pre XX century (e.g. neurology, but this also applies medicine as a whole, with anatomy being a huge "hot news" in early XIX century), some pre mid-XX century (neuropharmacology), with many emerging only after affordable computing boom of 1990s (basically entire modern neuroscience started with introduction of fMRI). You learn almost all pre 1850 scientific knowledge during modern, good high school course - MIT entry algebra exams from 1869 are at the late modern primary/early high school levels of complexity. Era of multi-field geniuses pushing knowledge forward by solo effort that XIX century is full of ended only around Manhattan Project.

And such basic concept of modern science as falsification is just 90 years old.

So wait, since the earth is flat, does this mean we have a hole in the dome? How do we plug it up?

 Necros wrote:
So wait, since the earth is flat, does this mean we have a hole in the dome? How do we plug it up?

A big ladder and some spackle should do it.

 A Town Called Malus wrote:
Oh wow, relativity without illustrations sounds pretty horrible

I recommend Why Does E=MC² by Brian Cox and Jeff Forshaw for anyone interested in relativity but not particularly confident in their maths/science ability. It does a great job breaking it all down into an easily understandable concept (well, as close as relativity gets to that). It also does a nice job of showing how easy it can be to derive the equations used in special relativity. You can literally get the lorentz factor for special relativity time dilation, length contraction, velocity transforms etc. using nothing more complicated than pythagoras' theorem, which is pretty cool. It only has a bit at the end about general relativity (much harder to derive anything mathematically for general relativity due to it's usage of differential calculus and tensors) but it has a nice thought experiment to demonstrate the point.

I'd highly recommend the PBS Space Time channel also. They usually do a pretty decent job in trying to make things understandable. Or at least it seems like they do to a dumb, dumb like me. 4D non-Euclidean geometry still throws me for a "loop" sort of, but I watched a video of Leonard Susskind explaining some of the mathematical principles relating to the "spacetime interval" that make sense, but sure are not "intelligible" to me.

To me, that the "speed of light" is a sort of "speed of causality" which is actually the "sapcetime interval" is actually really fascinating. Even if it "don't make no sense" to my monkey brain.

 H wrote:

To me, that the "speed of light" is a sort of "speed of causality" which is actually the "sapcetime interval" is actually really fascinating. Even if it "don't make no sense" to my monkey brain.

Mhmm. If the spacetime interval you're referring to is what I think it is then there's also another cool fact.

Thanks to special relativity, we know that different observers won't necessarily agree with the spatial distance travelled by an object (thanks to length contraction), or the time measured by a clock (thanks to time dilation). They won't even necessarily agree on the velocity of an object (unless that object is a photon). But, what all observers, no matter the differences in their measured times of an event and different measurements of the distance travelled, can agree on is the distance in spacetime that an object has travelled. You plug in each persons different measurements of time and distances and they will all come out to the same spacetime interval. A really nice demonstration of the fact that whilst it seems that relativity makes everything insane and confusing and paradoxical, it actually creates universal truths. No matter what perspective one is observing this stuff from, if you're careful and do your maths right, you will get the same answer as someone on the other side of the universe, even though all of your individual measurements are different.

That's pretty cool.

 Kilkrazy wrote:
Why the feth would anyone fake a pixellated image of a black hole? Aren't there better things to fake?

Because being first places you in the limelight and gets you a prestigous amount of press and acknowledgement. The outcome is that you are almost certainly get funded for further research, valuable permanent professorships and it sets up your science career for the rest of your like (financially and at the universities). The science field (especially astronomy) is pretty dog-eat-dog because of the relatively low funding. There will be people that actively try and disrupt others work or give themselves an advantage (steal results and data etc).

In the worst cases you can get the following scenarios. Firstly a scientist or team deliberately treat, falisfy or miscommunicate their findings to get the result they want. As in the case of Hwang Woo-Suk in Korea and stem cell research.

The alternative is that results are rushed to beat another party. In this case all other reasonable scenarios are not explored and a desired conclusion is drawn from the data without appropriate challenge. This was similar to what happened with the cosmic background radiation experiement using BICEP. In this case they went to early and claimed a result before exploring more localised causes of the effect (at a galaxy level) they were seeing. It made a big media splash and could be argued was solely done to beat another team using other data to the result.

Finally there can be concerns over the the programming tools used that can enhance features and over exagerate them. There is still some concern with the the results from the gravitational wave experiments and that it could be due to the way the software was written to search to find certain features. Last time I read the data and software hadn't been made publicly available so that the results can be challenged and that other scenarios can be excluded (i.e. the results are repeatable).

Now I am not saying that this is the case here, but there have been a number of cases relatively recently where the science has been shown to be a bit flakey because of the mad dash for money/publicity. People believing things are faked can be a natural consequence of this behaviour.

 A Town Called Malus wrote:

 H wrote:

To me, that the "speed of light" is a sort of "speed of causality" which is actually the "sapcetime interval" is actually really fascinating. Even if it "don't make no sense" to my monkey brain.

Mhmm. If the spacetime interval you're referring to is what I think it is then there's also another cool fact.

Thanks to special relativity, we know that different observers won't necessarily agree with the spatial distance travelled by an object (thanks to length contraction), or the time measured by a clock (thanks to time dilation). They won't even necessarily agree on the velocity of an object (unless that object is a photon). But, what all observers, no matter the differences in their measured times of an event and different measurements of the distance travelled, can agree on is the distance in spacetime that an object has travelled. You plug in each persons different measurements of time and distances and they will all come out to the same spacetime interval. A really nice demonstration of the fact that whilst it seems that relativity makes everything insane and confusing and paradoxical, it actually creates universal truths. No matter what perspective one is observing this stuff from, if you're careful and do your maths right, you will get the same answer as someone on the other side of the universe, even though all of your individual measurements are different.

That's pretty cool.

Well, again, from my "primitive" understanding, what we are discussing it what is invariant in preforming the Lorenz transformation.

Again, it is not as if I understand this, but this video is where I "essentially" got this from: The Speed of Light is NOT About Light. They even go on to explain that this (seemingly) must be the case, because the Lorenz transformation seems to be the case. If it were not, (seemingly) there wouldn't even be mass or space or time at all (because of how energy, mass and "c" seem to be related). In a similar way that we can suppose that a temperature absolute zero is not possible, because were that possible, it would grant infinite momentum, which would not seem to make any sense at all, given what else seems to be the case in the rest of physics.

The infinite momentum from absolute zero theory is based upon the fact that if you could make a cube of absolute zero, anything outside of that cube would be absorbed into it.

Almost exactly like how a black hole pulls everything in.

This is because the complete lack of motion by atomic particles would in theory absorb any energy from outside particles.

 Eihnlazer wrote:
The infinite momentum from absolute zero theory is based upon the fact that if you could make a cube of absolute zero, anything outside of that cube would be absorbed into it.

Almost exactly like how a black hole pulls everything in.

This is because the complete lack of motion by atomic particles would in theory absorb any energy from outside particles.

Interesting, although my monkey brain still wants to imagine "forces" in the Newtonian sense, whatever constitutes the "thinking thing" I seem to sometimes be knows this is not "true."

I just keep repeating to myself that John Wheeler quote: “Spacetime grips mass, telling it how to move... Mass grips spacetime, telling it how to curve.”

In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of a force. The starting point for general relativity is the equivalence principle, which equates free fall with inertial motion and describes free-falling inertial objects as being accelerated relative to non-inertial observers on the ground.[19][20] In Newtonian physics, however, no such acceleration can occur unless at least one of the objects is being operated on by a force.

Einstein proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths in curved spacetime. These straight paths are called geodesics. Like Newton's first law of motion, Einstein's theory states that if a force is applied on an object, it would deviate from a geodesic. For instance, we are no longer following geodesics while standing because the mechanical resistance of the Earth exerts an upward force on us, and we are non-inertial on the ground as a result. This explains why moving along the geodesics in spacetime is considered inertial.

Quite interesting.

However as a sci-fi fan I had never really doubted their existance so....

Real life is really very mundane.

Point of order: the image of the black hole on the previous page is not from Inception, but rather from Interstellar, a truly amazing movie on many levels! Indeed, the look of the black hole in that movie might be my favorite thing about it, as they captured exactly what one of those should look like.

One of my favorite things about black holes in general is how the extreme gravity messes with everything near them. Like, if you were close enough to the event horizon, you could actually see your own back in front of you! Really trippy stuff. And time slows way way down as well (something else they got right in Interstellar- that movie is just full of scientific win!) when you are close to the black hole, so you could essentially travel to the future by going close enough for long enough. The laws of physics as we know them actually break down once you cross the event horizon (the math starts giving nonsensical answers that aren't possible in our normal universe).

I’m no scientist by any means but I always thought Black Holes were super dense, super massive (as in lots of mass) objects with an extremely high gravitational pull and had nothing to do with magnetism?

 Nostromodamus wrote:
I’m no scientist by any means but I always thought Black Holes were super dense, super massive (as in lots of mass) objects with an extremely high gravitational pull and had nothing to do with magnetism?

Correct. Thus the "word salad" comment.

Why don't you try reading the Wikipedia page for black holes and then come back? You can ask better questions if you understand the fundamentals.

 Stormatious wrote:

 Ouze wrote:
Why don't you try reading the Wikipedia page for black holes and then come back? You can ask better questions if you understand the fundamentals.

I already did read about it dude, what i am saying is exactly how magnets act. Nothing can escape black holes etc because of gravity but in the case we can just say magnets.

If you find the topic annoying and cannot be bothered to even understand the basics of black holes (no, they aren't caused by magnets spinning), please just leave.

(deleting this, it's resolved)

 Stormatious wrote:
Im happy to leave knowing that i have stated why einstein is wrong with no one telling me how my explanation is wrong, just saying i dont know the basics, i have read it the wiki. Sorry that's such a big offense to you guys.

Einstein was wrong about what exactly? The existence of black holes. He himself didn't believe in black holes even though his equations on general relativity lead others to identify them later. Seriously, a basic understanding would help you out tremendously. https://en.m.wikipedia.org/wiki/Einstein%27s_unsuccessful_investigations

 Togusa wrote:

cody.d. wrote:

Unfortunately I have to make this comment, and I might get dinged for it, but, here goes...

This achievement has shown me just how uneducated, and poorly reasoned our society has become. Just reading through some of the comments today, listening to the media coverage has made my ears and eyes bleed. It's amazing how out of touch the public is with very simple science.

I'm actually curious as to what you mean? Like, you obviously seem to have some genuine knowledge/interest in the subject. Do you mean the "hole" part of the name confusing people? Much like how darkmatter isn't actually just stuff that's black but a sort of catchall term for a spectrum of stuff in the galaxy we don't quite understand yet. But then you see it in sci-fi as some sort of weapon material.

The general public reaction to this in news article comment sections has been terrible. People can't grasp why the image is so pixelated, or what the process was in recording this image. I've seen some of the most bat guano crazy statements about this out there, from people claiming it to be fake, to people claiming that it is a conspiracy. A local radio program yesterday (where my parents live) had a Scientist from UMKC on to talk about the discovery. After the segment was over, the two hosts began to make statements about the scientists "common sense." I'm not sure what the term for that is, but it's when a person feels intimidated by another, and so they try and belittle them for the thing that makes them feel inferior. It seems to me, as someone who has been involved in this field for many years, that each year that passes gets worse and worse for general science knowledge in the public. If you go to any NASA site that allows comments, 70% of the comments will be nonsensical, insane rantings, or cries of conspiracy. Probably because the internet has given people of lower ability spaces to congregate and share their ideas.

Another story I can share involves a Doctor my mother works with. I was speaking with him about another Astronomical topic last time I was home. I was amazed that someone who has set through college physics, couldn't grasp a simple concept (interferometry). Not even on a mathematical level, but on a conceptual level. It was truly a disheartening experience.

The dunning kruger effect springs to mind although it's not exactly what you described. It's basically because people have access to so much information nowadays they believe they are better informed than most experts on that chosen subject. Seen in large quantities in 'anti vax moms' who'd rather trust 'their own research' than science.