what's the difference between them ...which is real and which hypothetical??

(((Tom))) Your expertise is required....

I refuse to answer on the grounds I may incriminate myself

I'm sure Tom will be able to help you more than I can but I'll give it a go. Black holes have been observed and are known to exist. There's one at the centre of our Galaxy and most others. They are areas of space that held so much matter that the gravity well created by this concentration of matter became so great that not even light could escape and are effectively closed off from the rest of the universe. They are thought to be created when a particularly massive star reaches the end of its life. The physics of a black hole, especially what's at their centre isn't very well understood as yet, although the theories are improving all the time. Stephen Hawking probably contributed the most to our theoretical understanding of them. It's thought that when all other matter and energy has been swallowed by them, they will slowly dissolve through a process of emitting particles called 'Hawking Radiation".

Wormholes that link vastly separated areas of space have been hypothesised but never observed. Some Physicists have hypothesised that there is a wormhole at the centre of every black hole but can't decide where these lead to, if anywhere. Some Physicists have also hypothesised wormholes existing randomly in space but again these have not been observed and for the moment remain the stuff of Science Fiction rather than science.

White holes are the hypothesised opposite of black holes but again have not been observed to exist. They are hypothesised to return matter and energy to the universe that black holes have swallowed. Some think that if there are wormholes at the center of black holes then these link to white holes elsewhere in the galaxy or wider universe. I don't think that this idea is very popular now because of the lack of evidence.

Hope that helps but I'm sure that Tom would be able to give you chapter and verse on the latest Physics theories surrounding these ideas.

Seamus m8. that's pretty much it. as you said We need Tom on this one.lol.
I'm sure professer Tom Hawking will have something to add soon.

Yes, my physics is a little bit rusty so I'm looking forward to that .

That was an awesome read. Thanks Seamus

Thanks, I appreciate that. I do try to keep up with physics and cosmology but I was relying on my memory for that.

I think that the idea of white holes came about because of the apparent conflict between the laws of conservation of energy (it can neither be created nor destroyed, merely change form) and the assumption that if light couldn't escape a black hole, then neither could anything else. If the matter and energy swallowed by a black hole was effectively removed from the universe, then it was lost or "destroyed". So the singularity thought to be at the centre of every black hole was theorised to be the mouth of a worm hole and the matter and energy taken in by the black hole was thought to leak out elsewhere into the universe, thus preserving the conservation laws.
Since then, other mechanisms have been found which would also preserve the conservation laws and one of these is quantum tunneling. As a photon propagates itself as a wave and is "somewhere" but undetermined within the fan of probable locations and only becomes fixed to a definite place when a measurement is taken, there is also quantum tunneling. In this case a photon or other particle is propagating itself as usual, when it simply ceases to be where it was and reappears instantaneously further along it's projected course than it could possible reach even as a photon travelling at light speed. I don't think that there is an explanation for this, other than that quantum phenomena are probabilistic in nature. They have a range of possible outcomes and sometimes the result will be one of the vanishingly small possibilities that places the particle beyond where it could have been.
It was reasoned that even if all matter and energy was eventually swallowed and all the black holes gravitated together and formed a single huge
black hole, then over uncounted billions of years this last remaining black hole would eventually dissolve by losing all the energy it had absorbed through this phenomenon of quantum tunneling. Given enough time, everything that it had absorbed would escape by simply reappearing outside the event horizon of the black hole and once it lost the last of its energy, it would cease to exist.

Hi Guys and Gals!
Good Job Seamus!
LOL, I am just a disabled mechanic with a whole lot of time.
Personally, I never really agreed with Hawking but that is an entirely different discussion.

Black Holes
Try to realize the terms "Black Hole", "Dark Matter" and "Dark Energy" are placeholder names given to ideas and observations we have no actual words for.

A "Black Hole" is neither black or a hole.

It appears black because gravity is so great at its center, light cannot escape.
It acts like a hole because things we see getting pulled to it seem to disappear forever. Like they go into a hole.

The black is defined by what is called an "Event Horizon".
The Event Horizon of light is the boundary where the gravity is so powerful light can't escape.
There are other "Event Horizons" as well.
The Entire Milky Way galaxy is within the event horizon of Sagittarius A (the "supermassive" 'black hole' at the center) and is why everything in the galaxy is spiraling towards it.
There is also a more distant event horizon which captures our local dwarf galaxies known of as The Local Group.
Many people "think" the term "Event Horizon" only applies to a black hole's light boundary. This is an error. Event horizon is actually just the horizon of influence of something on something else.

We see it as black so we think it must be black. Its is merely the absence of light because light never makes it to our detectors/eyes.

Now, think about "Hole".
Its common to think matter falls INTO a black HOLE because it disappears never to be seen again. The mind demands it must 'go' somewhere so we think it goes into a hole.
However, if it were an unseen hole in space-time, falling into another dimension or Universe, once it falls in, it would no longer exist in our Universe. If it no longer exists in our Universe, how can any black hole get larger and larger? How can any black hole influence this Universe if it no longer exists in this Universe?
I don't believe matter falls into a hole at all.

Consider what we understand about star formation.

Dust and gas start to coalesce. The matter clumps together into larger and larger clumps and the increase in mass increases its gravity.
With more gravity, more mass is collected resulting in even more mass and so on.
As the mass is collected, it collects unequally and the force of mass hitting the object at an angle cause it to spin. As it collects more and more mass on to the object the mass is packed tighter and tighter as the gravity increases.
Eventually, it ignites as atoms of mass start to fuse under the immense gravity.
As long as there is more mass within its gravity influence (event horizon) it continues to get more and more massive.
At a long distant point in time, the mass becomes so great, even light is captured by its gravity.
The object becomes what we call a black hole.
It was a super-massive star when we could see it.
Now we only see black but inside that horizon of black, it is still a super-massive star. Remember, super-massive does not necessarily mean big.

The size of the object is shrinking because its gravity is packing it tighter and tighter.
There MUST be a limit to how dense a mass can be because if there wasn't, the object would continue to pack tighter and grow smaller as it accumulates more mass.
The FACT that black holes grow indicates there is a limit to mass density.
A singularity point.

Now think about why a star gets brighter and brighter as it gains more mass.
Its getting hotter because the act of ramming mass together produces heat.
As the black hole collects mass it gets more massive which makes the mass slam harder onto it.
That mass singularity in the middle of that black horizon is white hot.
Brighter than any other mass in the Universe.
Its spinning.
As mass is collected, it collects at its equator. The resultant energy builds and the excess is thrown out at its poles in the form of gamma ray jets.



A Black Hole is not a black hole, it is a White Singularity.
It only looks like a black hole.
Matter does not fall "into" a black hole it is gravitationally drawn to the singularity mass so it falls "Onto" not "Into" then it is absorbed by the mass.

White Holes - Yeah, I read science fiction and fantasy too.

Worm Holes
Einstein–Rosen bridge (Schwarzschild wormholes)
In 1935, Einstein and physicist Nathan Rosen used the theory of general relativity to elaborate on the idea, proposing the existence of "bridges" through space-time. These bridges connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance.

Space-time is imagined as a fabric stretched across the Universe.
This fabric of space-time is how we model the effects of gravity on mass.
Like a bowling ball on a trampoline.
A worm hole is a hole in that fabric which connects to another distant hole like a folded piece of paper with a pencil poked thru both ends of the paper.

I have a problem with worm holes.
While it all seems logical considering space-time may be a fabric it fails to consider one very important point of space-time.

Space and time is not flat like a piece of paper.
The gravity well example we have all seen is not accurate.
Space and time is a volume, not a flat surface.
Mass affects gravity in a sphere around it.
It does this because space-time is a volume.

The Einstein–Rosen bridge would have to pierce infinite volumes of space-time to connect back onto itself. The problem with that is the folding of space-time. Can you fold the water in a bucket so one side of the water connects only with the other side of the water submerged in the center of a lake? Can you fold a column of vacuum in a larger vacuum?

I'm a dreamer.
I like to think somewhere in this Universe there is a technology that can create worm holes. It would be pretty cool.
While worm holes make for some fun science fiction and fantasy, I doubt they exist.
I admit I've fallen behind on my quantum theories.
Worm holes might be possible in quantum, I don't know.
There have also been some recent discoveries/theories on time travel which I have not read yet. Time travel relates to worm holes.
Time travel is another thing I can't agree with, but that is an entirely separate discussion.

Anyway, those are my thoughts on the subject.
Just one man's opinion.

well what about Einstein-rosen bridges?

This was covered in the previous post.

I can recommend a very interesting documentary series with Neil deGrasse Tyson
"Cosmos: A Spacetime Odyssey" :)

While I like NDT and his version of Cosmos, Dr Sagan's Cosmos really inspired me to find out more about science. I also bought and read Pale Blue Dot which was wonderful.
I remember a kiosk at the planetarium in the St Louis Science Cente had a short video playing Powers of Ten. I liked how it went small and large.
Just recently I found an kinda/sorta video on youtube by Metal Ball Studios which looked at a similar journey.
UNIVERSE Size COMPARISON [EVERYTHING]
http://www.youtube.com/watch?v=NrRPg0pH9xc
What was interesting is the fact it starts at Quantum Foam/Planck Length.

They also do...
BLACK HOLE in perspective
http://www.youtube.com/watch?v=Xw19Z1xkzJ4

and

STARS Dimensions | MetaBallStudios
http://www.youtube.com/watch?v=kBkNhMfrxuk

Thank you so much for your recommendation, I will watching it with pleasure

Seamus thanks for your explanation...you stated it well, hate the name wormhole tho, wonder why it was name that.

Technically, the correct name for them is Einstein-Rosen bridges, so 'wormhole' is just a non-technical, visual term for the posited tunnel linking two regions of space.

I happen to be a big fan of NDT, if only for his connection to Sagan's legacy...

If you hadn't heard NDT's story of meeting Sagan I strongly suggest so, Sagan "took him under his wing", the story is very touching, inspiring. I leave you to google it, look for Neil himself telling it in his own words.


As for your upper post, regarding Worm-holes, I recently posted a thread on faster than light, relating to the fact that intergalactic space is spreading at FTL speeds...in fact, 95% of the visible universe is spreading away from us that fast.

This would then yield "evidence" to the Einstein–Rosen bridge theory of worm holes, only in the fact that we now know space is actually spreading ftl without affecting the matter around it means if space/time can actually be stretched, it can be compressed, "folded", bypassed...

<oops>

Speed is relative to the observer.
Two jets are flying at the speed of sound beside each other.
To the other jet, the one jet is barely moving but to a crusie ship, the jets are fast moving. You see the same thing anytime you are driving with the flow of traffic vs walking.

Intergalactic space has less mass density than galactic space.
Galaxies are heavier so they are slower moving than objects which are in the lighter, intergalactic regions. The assumed speed limit of mass in this Universe is the speed of light (the speed of a photon wave moving thru a complete vacuum).

There are regions of space known as voids.
Within these voids we have observed no mass (stars).
The voids are the closest thing we can measure which has no accumulated mass.
Velocities within these voids would not be slowed by mass effect.
Voids are the closest things to a complete vacuum in intergalactic space.


(A few voids are labeled in red)

The Universe is dynamic. Different regions move at different speeds.
Mass is the speed limiter. Our view of the Universe is extremely limited.
We are locked within the mass of this galaxy. We are locked within the confines of mass because we are made of mass. Our view is relative to our environmental restrictions. Therefore any laws we know, are restricted to our own limited conditions and may not be the true laws of the Universe.