Whoa...

[aspnetguy]

sorry for bring up the discussion, I just don't like when generalized stereotypes are thrown out there.

[Chocolate570]

Skemcin, that's an entirely true point. Galaxies are like atoms. They attract eachother, have different components, and are relatively tiny compared to what holds them (the universe).

[Err]

Space is really amazing. There just has to be other life out there. Too bad we don't have the technology nor time to get to other glaxies in the universe. Hey who knows, we might get lucky and other intelligent aliens from an advanced race might come a visit us. We can still hope.

[aspnetguy]

I liked the illustration they used:It would take the USS Enterprise travelling at warp 9.6 10 million years to get to the next closest galaxy..that's prett far

[holmedwa04]

But has anyone thought about moving on from our universe and into another? It is just such a wierd concept to grasp that space go on and on forever.Because if it doesn't then what is after it and if it does surely it must end, just two different contraditions.Wow, I never knew space could be so interesting. I was at one poin making a website about space but I never got round to completing it!

[justsomeguy]

The universe is continually expanding. Assuming the Big Bang went down as is theorized, ever since then the universe has been expanding. The question is what is the universe expanding into, and will it ever stop expanding and start contracting? If you have the answer to that, please share.

It would take the USS Enterprise travelling at warp 9.6 10 million years to get to the next closest galaxy..that's prett far

Yeah, but that's assuming you are moving in a linear fashion. If you could fold space/time so that the origin and destination are right next to each other, then you can just step across. Cmon, haven't you ever seen Event Horizon? What could possibly go wrong?

[aspnetguy]

The universe is continually expanding. Assuming the Big Bang went down as is theorized, ever since then the universe has been expanding. The question is what is the universe expanding into, and will it ever stop expanding and start contracting? If you have the answer to that, please share.Yeah, but that's assuming you are moving in a linear fashion. If you could fold space/time so that the origin and destination are right next to each other, then you can just step across. Cmon, haven't you ever seen Event Horizon? What could possibly go wrong?

Actually no I haven't seen Event Horizon

[holmedwa04]

Wow, this topic is really interesting, I thank whoever bought it up. Space could drive anyone round the bend trying to work out why it is what it is and how did it form, and what is it expanding into and so on. And how come if you entered a black hole you would be stretched like spagetti before you could say bobs your uncle?In fact that is a scare thought, being sucked into a black hole. Am I rigth in saying that they have a huge gravitational pull?

[Jonas]

I was at one poin making a website about space but I never got round to completing it!

Here's the closest thing I ever got to making a website about space:http://www.home.no/jvelde/solarsystem/Click and drag the sun to where you want it, press start in the upper left corner, and the sun's gravitation will drag the planets to it and send them orbiting around it.

Am I rigth in saying that they have a huge gravitational pull?

Understatement.

[justsomeguy]

And how come if you entered a black hole you would be stretched like spagetti before you could say bobs your uncle?

It's because of the gravity, like you mentioned. Black holes are pretty interesting. They form a lot when supergiant stars collapse and explode. All the mass gets drawn into the dead core of the star, and as more and more mass gets sucked in, the thing gets more and more dense and starts spinning faster and faster. Eventually, it gets so dense that it even pulls in light. That's why they are called black holes, there is in fact an object at the center of it, but we will never be able to see it because the gravitational pull is so strong that not even light can move fast enough to escape it. There is a certain distance from the object to where light can escape, meaning that light at that distance away will still be able to escape, but anything closer gets drawn in. That distance is known as the event horizon of the black hole, because any events that happen inside the boundary don't get seen. So, if you point a telescope at a black hole it will look like a big black sphere, but the object inside is actually relatively small, just really dense. Black holes are typically at the center of galaxies, so the gravitational pull is strong enough to make large objects that far away orbit.I think that neutron stars are even more dense then black holes, I heard somewhere that one thimble-full of neutron star matter would weigh about as much as Mt. Everest. I also remember a report about 2 black holes colliding with each other, but I can't remember if the collision already happened and we saw the effects, or if it was going to happen in the near future.Even scarier then black holes colliding is the concept of a moving black hole. A black hole flying through space sucking up everything it meets is a pretty scary concept. You would never see it coming, and the planet would be destroyed before anyone knew what happened.

[reportingsjr]

That is in fact all a black hole is, a tiny sphere that has tooons of mass so it has an immense amount of gravitational pull. One thimble full wouldnt wiegh as much as mt everest, who even knows how much mt everest ways? I think that its more like a teaspoon is around 50~100 tons. But how should we know? We couldnt find out if we wanted to right now. (Maybe later when we create something strong enough and fast enough to withstand the gravity. And to wiegh it..)I think it would be fun to see 2 black holes collide. Heres my prediction of what would happen:1. they get nearer to each other.2. The closer they get the faster they go towards each other, the gravity is pretty strong after all.3. they collide4. Boom5. the two A) create some new super star from the explosion B ) just make the black hole bigger and have more gravity.6. Either way the objects around the two will either get blown up or get sucked in closer to the new object there.

[justsomeguy]

According to Wikipedia, the density of a neutron star is between 8×10^13 to 2×10^15 g/cm³. So, a cubic centimeter (about the size of a thimble) would weigh between 80,000,000,000 kg and 2,000,000,000,000 kg, or 88,184,904 - 2,204,622,620 tons on Earth (thanks Google). So, somewhere between 88 million and 2.2 billion tons. I'm not sure how much mass is in Mount Everest, but the mass of the Earth itself is 5.9742×10^24 kg, so it would take about 2 billion cubic centimeters of neutron star to equal the mass of the Earth. The numbers are a little big to think about, but we can estimate the mass of Everest by using the height and width and the average density of the rock that makes it up. But scientists generally use comparisons like that because it's a little hard to think about if they say 1 CC of neutron star matter is up to 2 trillion kilograms.Wow, strap on your nerd glasses and check out the Wikipedia page about black holes.

Spacetime inside the event horizon of an uncharged non-rotating black hole is peculiar in that the singularity is in every observer's future, so all particles within the event horizon move inexorably towards it (Penrose and Hawking). This means that there is a conceptual inaccuracy in the non-relativistic concept of a black hole as originally proposed by John Michell in 1783. In Michell's theory, the escape velocity equals the speed of light, but it would still, for example, be theoretically possible to hoist an object out of a black hole using a rope. General relativity eliminates such loopholes, because once an object is inside the event horizon, its time-line contains an end-point to time itself, and no possible world-lines come back out through the event horizon.

BTW, I was way off-base when I said neutron stars might be more dense then black holes. Black holes can have an infinite density, so that sort of settles that.

[reportingsjr]

Ok, maybe I was off.. Just a little though . :)0.o, how are we supposed tounderstand that? Im guessing that it means once something goes into a black hole it doesnt come out because when it ends it will be the end of time (since its always try to move to the center of the black hole nothing will ever be there to destroy it.). I would be really interested to see what a black hole really looks like. Ive never even seen a picture of a black hole either. But would be cool to see the actual star inside of this "hole".

[holmedwa04]

Wow, black holes are really interesting, do you think someone could write a whole book on black holes? In fact it seems scary that it could have sucg a gravitational pull, anyway, why don't they just start to take (can't use another word) the whole of space up, and our plants? Also surely eventually they would get so dense that they would just explode themseves and recreate the big bang.HEY, these as theory, eventually everythin gets sucked into a black hole and then it explode and the universe starts again!What do you think to that?

[reportingsjr]

errrr, why would it explode? It always stay pretty much the same size, and they are stationary. So you are kind of right, most things tend to stay away from them or the would get sucked straight in. Their gravitaional pull is so strong that it just keeps compacting it own self more and more, hence why it stays the same shape. Also, they would be a literally perfect shpere. What color? im not sure...I dont see why it would explode though..

[justsomeguy]

I would be really interested to see what a black hole really looks like. Ive never even seen a picture of a black hole either. But would be cool to see the actual star inside of this "hole".

I'm guessing it's very dark in color, maybe dark brown or black since it's sort of made up of everything. But, it might not even be visible. One theory is that the object itself is a 'singularity', meaning that it doesn't have a size but exists at a single point. The matter is compressed so much that it doesn't even have a width, it just exists.As for pictures, there aren't any. We see the effects of black holes, but you can't see the black hole itself. What you would see is a phenomenon called gravitational lensing that makes the light around black holes bend. Here is a simulated view of a black hole of 10 solar masses (10 times the mass of the sun), seen from 600km away in the Milky Way:http://en.wikipedia.org/wiki/Image:Black_Hole_Milkyway.jpgThe distortion you see is because the light that passes near to the source of the gravity is bending, so the things you see on the edge of the "hole" are actually objects that are behind it. Here is an actual picture of the effect, which in this case is caused by a supercluster of galaxies and stars warping the light around it. The arcs you can see surrounding the cluster come from distorted galaxies directly behind it:http://en.wikipedia.org/wiki/Image:Abell.l....arp.750pix.jpgI was about to draw a diagram to explain gravitational lensing like my physics teacher did, but the wikipedia page has a good illustration (in the Description section):http://en.wikipedia.org/wiki/Gravitational_lensThe white arrows are the actual path that the light takes, but since it gets to us and appears to be coming at an angle, the orange arrows show the relative position that we think we see the object at.

Wow, black holes are really interesting, do you think someone could write a whole book on black holes?

Yeah, A Brief History of Time by Stephen Hawking. Einstein also has a lot of theories about black holes that were a part of his theory of general relativity.

Also surely eventually they would get so dense that they would just explode themseves and recreate the big bang.

You might think, but there is a threshold. It's the same force that keeps a star together. A star is basically a constant explosion while it burns hydrogen. But it doesn't just outright explode because the gravity of the star itself keeps the explosions in check. When a star goes supernova and explodes, it's because it has burned off so much hydrogen and has lost so much mass that its gravity can no longer contain the explosion, and it collapses and explodes. So, with the amount of gravity that a black hole has, and the fact that it only gains mass and never loses it, all they can do is grow. It might be constantly exploding for all we know, but we will never see the effects of that because no information ever leaves the black hole. Even if two of them collide, the escape velocity required for an explosion to leave the black hole would be far more then the speed of the explosion, so we would never see anything. Two black holes would collide, and it would be incredibly violent, but it would look like a peaceful 'merge'. However, the matter orbiting around the black holes that hasn't made it inside the event horizon yet would be thrown every direction, and we would definately see that. I read something on the wikipedia black hole page that said that scientists have observed a giant blue star travelling away from the center of our galaxy at twice the escape velocity for the galaxy, which is something like 0.0022 times the speed of light, which is rediculously fast. So, if a black hole can fling a giant blue star (which is extremely large, dense, and young) that fast, it sort of gives you an idea of the forces involved.

why don't they just start to take (can't use another word) the whole of space up, and our plants

They are at the center of galaxies, so given enough time they would swallow the entire galaxy. But it would take a very very very long time to do that.

[reportingsjr]

As for pictures, there aren't any. We see the effects of black holes, but you can't see the black hole itself. What you would see is a phenomenon called gravitational lensing that makes the light around black holes bend. Here is a simulated view of a black hole of 10 solar masses (10 times the mass of the sun), seen from 600km away in the Milky Way

Errr, I hope to god that one never comes anywhere even close to that far away from us. That would mean we would most likely start to get sucked in. That is actually really close considering that mars (closest planet to us) is alot farther away from us. That means its stuck in the suns gravity, and the black hole has a tad bit more gravity than the sun =\.

[justsomeguy]

If we were 600km away from a black hole, the Earth would already be in several pieces. The moon is over 384,000km away, so 600km puts it relatively right above the surface. We would have a great view of it, but sadly the view wouldn't last very long. But that's also a black hole of only 10 solar masses. The black hole at the center of our galaxy is thought to be 3.7 million solar masses.

Supermassive black holes have some interesting properties which distinguish them from relatively low-mass cousins:The average density of a supermassive black hole can be very low, and may actually be lower than the density of water.

Wow. Imagine the size of something with the density of water 3.7 million times the mass of the sun.

[holmedwa04]

Wow, I never realised that what Stephen Hawking wrote was about Balck Holes.

[justsomeguy]

That's only part of his field. He writes a lot on space/time in general, and has done a lot of research on black holes. He has a book that is a collection of essays called Black Holes and Baby Universes and Other Essays, and his books are A Brief History of Time, The Universe in a Nutshell, and A Briefer History of Time. He also has some downloads on his lectures page:http://www.hawking.org.uk/lectures/lindex.htmlHe also makes bets.

"This was a form of insurance policy for me. I have done a lot of work on black holes, and it would all be wasted if it turned out that black holes do not exist. But in that case, I would have the consolation of winning my bet, which would win me four years of the magazine Private Eye. If black holes do exist, Kip will get one year of Penthouse. When we made the bet in 1975, we were 80% certain that Cygnus was a black hole. By now, I would say that we are about 95% certain, but the bet has yet to be settled." (1988) According to the updated 10th anniversary edition of A Brief History of Time, Hawking has conceded the bet "to the outrage of Kip's liberated wife" due to subsequent observational data in favour of black holes.

[holmedwa04]

Yeh, I knew what books he had written, I just had never really thought what they were about, I did part of my ICT coursework on him, and about how ICT has helped him.

[reportingsjr]

me four years of the magazine Private Eye.Kip will get one year of Penthouse

So they liked porno? Interesting . Thats priceless.. steven hawking and some guy named kip bet on things using porno as currency .For some reason I dont think black holes have a density less than water. I mean... comeon?This has grown to be quite the topic so far..

[justsomeguy]

That's Kip Thorne, he's done a lot of research on gravity waves, black holes, wormholes and time travel. Private Eye is actually a satirical news magazine, but I guess Kip wanted the skin rag.

[Ruud Hermans]

Even scarier then black holes colliding is the concept of a moving black hole. A black hole flying through space sucking up everything it meets is a pretty scary concept. You would never see it coming, and the planet would be destroyed before anyone knew what happened.

To make that more scarier we got a few moving black holes in our galaxy and one of them is pretty huge.To get back at the universe expanding witch I read I think on the first page this is called "The big cut" the moment the universe reaches it's maximum width and implodes swallowing everything even time, light and darkness.Makes you wonder.....what's the meaning of life???Btw. Einstein was a fake his o so famous theories where discovered before by others only thing he did was explain them in a way every one could understand.Ruud Hermans

[reportingsjr]

I dont think so ruud.. It was actually his wife who came up with most of his ideas. He was reaaaaaaallly horrible at math. Hence why he dropped out of school. Ok, private eye wasnt a porno but penthouse is