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Originally posted by Acid Junkie some astronomers believe that when u travel through a black hole, u go through a tunnel callde a wormhole where u are changed changed into pure energy (according to einstein.) then u come out of a so-called white hole. if a white hole exists, it should be asmall body in space that sends out a lot of pure energy. other astronomers believe a worm hole is a portal to other univreses. they believe that matter changes going through a black hole and creates a new universe with its own spacetime continiuum. in other words worm hole = tunnel to a white hole at some other point in spacetime

hmmm i always liked the theory that the opposite end of a black hole is a quasar (ie. a white hole)..

but the term worm hole in its simplest term i guess would be a shortcut thru space by the folding of space. Like for example, if u are at one end of a piece of paper and u want to get to the other side in the quickest possible time, the best way to do it would be to fold the piece of paper in half and just step across. And as far as time travel goes, at the moment, the only way to do this would require worm holes to actually exist (which atm we dont even no if they do exist) and we would also need to be able to reach greater speeds than that of light. As already explained a few posts above, when travelling at the speed of light you dont encounter the same time as everyone else. Like you could go speeding away from earth at the speed of light and come back within minutes to find everyone on earth has ages thousands of years. But in theory it is this that makes time travel possible. If you could somehow take hold of one end of a worm hole and go flying off with it at a velocity of over the speed of light, then come back to the starting point, then in theory what you have done is made one end of the worm hole one time period, and the end which u dragged flying off into space at great speeds in a different time period.. and therefore if u were to step thru that worm hole ud be stepping from one time frame into another.. hurrah! uve just travelled thru time

hope i havnt bored anyone there but i find this sort of topic fascinating.

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Originally posted by DJ Mikey Mike but the term worm hole in its simplest term i guess would be a shortcut thru space by the folding of space. Like for example, if u are at one end of a piece of paper and u want to get to the other side in the quickest possible time, the best way to do it would be to fold the piece of paper in half and just step across. And as far as time travel goes, at the moment, the only way to do this would require worm holes to actually exist (which atm we dont even no if they do exist) and we would also need to be able to reach greater speeds than that of light.

ya, that's what they often wright in science fiction stories. what they don't say is that even if worm holes really exist, chances are u will be torn apart and fried long before u've gotten to the other end

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Originally posted by DJ Mikey Mike hmmm i always liked the theory that the opposite end of a black hole is a quasar (ie. a white hole)..

Nice point you made, but just so you know, a quasar is not a white hole. Quasars infact consist of a black hole in the middle and a very hot cloud of gas around it that's generating large amounts of energy when it is falling into the hole. And while the existance of black holes and quasars is a quite common phenomenon, the existance of white holes has so far not even been hinted at. Infact, most physicist consider their existance very unprobable. Unlike a black hole, a white hole is in contradiction with the simple laws of thermodynamics. A white hole is spewing matter out of nowhere, while a black hole is gathering matter into a singularity, but at a same time radiating thermal energy equal in amount to the swallowed matter. When a wormhole is left with no matter around it to feed itself, it basically converts all of it's matter and energy into thermal energy which it radiates into the surrounding area, and eventually, it deteriorates itself to nothingness.

Btw, if anyone is interested, there's a nice book I'm just reading, "The Nature of Space and Time" from Stephen Hawking and Roger Penrose. The book is pretty interesting, but to understand it fully I'd say you need at least two years of university-level physics/mathematics worth of knowledge. Anyway it says a lot about black holes and the nature of space-time, but it doesn't say much about time travel and such.

stephen hawking? is he the guy who speculated that black holes supposedly radiate with a black body spectrum and thus lose their mass and eventually die sounds good except no one was ever able to detect that radiation

Yes, that's him, but it's not just a speculation, it's a physical model that does make sense. But the radiation hasn't been detected because all black holes we observed so far are surrounded by clouds of hot gas, which make it impossible to detect fainter radiation those black holes might emit.

I did a research project on Isaac Asimov and he states (or theorizes) that wormholes are open randomly throughout space for only fractions of MORE fractions a second. I'm guessing that if we ever want a chance to ride into one, we need to slow down time so we can see and enter the wormhole, and see where it leads to

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Originally posted by DrUg_Tit0 Yes, that's him, but it's not just a speculation, it's a physical model that does make sense. But the radiation hasn't been detected because all black holes we observed so far are surrounded by clouds of hot gas, which make it impossible to detect fainter radiation those black holes might emit.

Dammit just found this intersting thread. Anyway yes blackholes can die because they radiate.

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In classical Newtonian physics, black holes are black. But on a quantum mechanics level, they radiate an exceedingly small number of particles, mostly photons. Nobody has verified this weird phenomenon, called "Hawking Radiation", but it makes sense in a strange way. According to Heisenberg's Uncertainty Principle, our space vacuum teems with invisible particles that flash into and out of existence like virtual fireflies. Suppose a pair of particle-antiparticles pops into being, conveniently enough, within effective range of the black hole's gravity. Before the pair can annihilate each other, the black hole grabs the pair and, using the hole's rest-mass energy, pulls it into two particles. "...one particle has negative energy and the other has positive energy," says Andrew J.S. Hamilton, astrophysical and planetary sciences professor at the University of Colorado. "And the black hole swallows the negative energy, allowing the positive energy particle to go to infinity." The black hole loses the energy contained in the escaped positive-energy particle, consequently loses an equal amount of rest mass, and eventually--after enough positive-energy particles escape-loses all rest mass and dies. Don't hold your breath. The death of a black hole can take ten raised to the 61st power times the age of the Universe for a 30 solar-mass black hole. Mini black holes-the mass of a small mountain-can evaporate in less than the age of the Universe. The black hole glows extremely dimly. The Hawking luminosity of a 30 solar-mass black hole is a miserable ten raised to the minus 31 watts. Bigger black holes are colder and dimmer. So, on a quantum mechanics level, a black hole isn't completely black. It glows faintly. Emitted x-rays are another matter completely. The black hole doesn't emit the x-rays. Rather it pulls hot gas away from its Sun-like companion star if it has one. The gas forms a flattened disk swirling around the hole. The gas particles knock into each other zillions of times as they rotate and heat to extreme temperatures: hot enough to emit x-rays. The gas particles reach the right temperature when they are close to the event horizon. (The event horizon marks the critical limit where the escape velocity of a collapsing body becomes equal to the speed of light and hence no information can reach an external observer). Then they spit X-rays in all directions and less than a second later disappear. See illustration. In the figure, the swirling material (white circles) is hot gas pulled from the black hole's companion star. The gas reddens and dims due to a gravitational red shift as it approaches the event horizon (black center dot). Photons lose energy in the presence of a strong gravitational field and this causes a shift to lower frequencies, i.e., a red shift. When the gas crosses the event horizon, it disappears.

So if the universe is forever expanding as is indicated then the entire universe will eventually die out into nothingness.

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Originally posted by DrUg_Tit0 Btw, if anyone is interested, there's a nice book I'm just reading, "The Nature of Space and Time" from Stephen Hawking and Roger Penrose. The book is pretty interesting, but to understand it fully I'd say you need at least two years of university-level physics/mathematics worth of knowledge. Anyway it says a lot about black holes and the nature of space-time, but it doesn't say much about time travel and such.

Also a good book that I'm reading is the Whole Shebang Theory by timothy ferris. Again some college phsyics is a plus. If you want something a little bit lighter maybe try Hawking's The Universe In a Nutshell.

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Before the pair can annihilate each other, the black hole grabs the pair and, using the hole's rest-mass energy, pulls it into two particles. "...one particle has negative energy and the other has positive energy," says Andrew J.S. Hamilton, astrophysical and planetary sciences professor at the University of Colorado. "And the black hole swallows the negative energy, allowing the positive energy particle to go to infinity."

This kinda doesn't make sense. The hole has equal chances of grabbing both negative and positive particles. So if we rely on vacuum fluctuations alone, positive and negative energy fluctuations should cancel each other out on a large scale.

It is not up to you or I to question why but to do or die.

But seriously I'm sure the actual explanation goes a little bit more in depth. I'm not going to even try (unless I get bored) and look up specifics since I'm sure it's very complicated and likely over my head.

Hm, it mentiones something about positive and negative frequencies of energy, not particles, but primarily it says that the hole itself has an internal entropy that is generating heat regardless of the outside influence. But I may be wrong because I don't understand half of what is being said.

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Originally posted by DrUg_Tit0 And while the existance of black holes and quasars is a quite common phenomenon, the existance of white holes has so far not even been hinted at. Infact, most physicist consider their existance very unprobable. Unlike a black hole, a white hole is in contradiction with the simple laws of thermodynamics. A white hole is spewing matter out of nowhere, while a black hole is gathering matter into a singularity, but at a same time radiating thermal energy equal in amount to the swallowed matter. When a wormhole is left with no matter around it to feed itself, it basically converts all of it's matter and energy into thermal energy which it radiates into the surrounding area, and eventually, it deteriorates itself to nothingness.

yes, i agree, though white holes can be considered an interpretation of schwarzschild's solution (negative square root solution inside the horizon), the possibility of their existence remains somewhat shaky. however, i must say i like the theory according to which the big bang is actually just a huge white hole taht formed in a different universe... even though it ignores the fact that white holes and big bang are two completely different solutions of the equation that cannot be converted into each other well, anyways...

if only i could get my hands on this time machine i would delete all lame threads (this one included ). For that matter i would get some Precogs to detect lame poster and send the lame police to arrest the would be poster at his home before he could send it to the TA.

i loved this thread to death! it's great.

about a quazar

black holes are invisible because it captures light.
shouldn't white holes (or quazars i think) be the brightest thing in the universe?

actually, a quasar is not the same as a white hole. a quasar is a special case of a BLACK hole. when something approaches a black hole it gets torn apart by gravitational forces. the formed debris then starts to rotate falling into that black hole. as it gets closer to the event horizon, it speeds up and thus heats up (because of friction). so it begins to emit x-rays that can be detected. now, if a black hole itself is very big and if there is a lot of debris that spirals into it, such a black hole can become really bright and emit enormous amounts of high-energy matter. in this case, it's called a quasar.

also note that such an emission of energy is NOT caused by nuclear fusion that takes place in normal stars.

i am more interested on any further developements of this story!

come on, wether you belive in time travel or not, id liek to see how he could make all that money on jsut "inside information" alone.

is the speed of light constant?

is there any way of slowing/accellerating the speed by weater, magnetic fields, beams of certain energy, etc?

In addition to requiring infinite energy, isn't an object supposed to expand to an infinite two dimensional plane if it goes over the speed of light? I remember reading something to that effect in one of Ferris' books a year or two ago, but I'm too lazy to dig out the notes right now.

One other interesting factoid on black holes too, as has been stated, to an observer you'll never actaully cross the singularity. Say for instance that you're a safe distance away watching a cosmonaut with a watch on falling into a black hole and you could see the hands of the watch.

As said cosmonaut got closer and closer to the singularity the second hand of the watch would go slower and slower until it seemed to stop moving right before crossing the singularity.

At that point an image of the cosmonaut would appear to be frozen in time, and is theoretically going to exist forever, though in reality it's believed it would actually disappear from sight in relatively short order.

The actual cosmonaut in question is getting a much different view though, for them time never seems to slow down as they cross the threshhold of the singularity. They'd continuously fall, and start to find themselves stretched, eventually, over the course of days, being stretched into what Hawking termed 'human spaghetti'.

Cosmology on this level is largely beyond me, but just reading a touch of it is extremely interesting. I'll join occrider in saying that Timothy Ferris does some good stuff that's by and large understandable for the average person, if you take some time with it at least.

And on the origin of the original article, Weekly World News is a tabloid that prints all kinds of ridiculous stories ala "Demons from Hell Kill 11 in Church Attack!" and "Alien Supports Bush Election Bid", so never, ever, ever, take a story with that name on it as anything other than complete crap

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Oriignally posted by djSlain is the speed of light constant? is there any way of slowing/accellerating the speed by weater, magnetic fields, beams of certain energy, etc?

of course u can change the speed of light. different evironments will yield different speeds. c=186,000 miles/second is the speed of light in a vacuum ONLY. for example, in water, its speed would be about 139,000 miles/second. if light goes through a piece of glass it slows down to approximately 125,000 miles/second, etc. but nothing can move faster than light in a vacuum.


edited because i can't spell

According to Einstein, faster than light travel is possible only if repulsive gravity existed. This is the basis of the theory of cosmic inflation. A Portuguese physicist named Joao Magueijo (I can't type the accents on the letters) has another idea about this. If the speed of light were faster in the past, it would also fit the theory. So, light might not be what we think it is...

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Mack & DrUg_Tit0 id love to have a smoke with u guys

decode, come over to Canada, marijuana is gonna be decriminalized soon

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but the term worm hole in its simplest term i guess would be a shortcut thru space by the folding of space. Like for example, if u are at one end of a piece of paper and u want to get to the other side in the quickest possible time, the best way to do it would be to fold the piece of paper in half and just step across.

good analogy, that is the simplest way of explaining it, I read that off some website some years back. It may seem easy enough, but the wormhole is very unstable, and quantum sized.

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though white holes can be considered an interpretation of schwarzschild's solution (negative square root solution inside the horizon

acid junkie, I thought a negative square root solution for the schqarzschild equation meant the existance of wormholes?

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is the speed of light constant?

nope. light's "constant" speed of 300,000 km/second is only true in a vacuum. when travelling in other mediums, it can be slowed down somewhat. Recently I heard a report that a group at Caltech slowed down light particles to a halt in a controlled Cesium gas chamber, not too sure about the details though. But the speed of light in a vacuum is regarded to be the maximum speed of anything in the universe(to our knowledge right now..its not concrete because nothing is for certain)...but this explains why time starts to behave strangely(along with events) when approach light speed.

Also, astronomers use this feature of light to detect anomalies in space without directly viewing them, by calculating how the speed of light emitting from a star variates from a different star almost equivalent in distance, to show that perhaps a large planet nearby is bending the light due to its enormous gravitation pull on light. This deviated path can illustrate a vivid picture itself. Light(in every aspect of the spectrum) helps us to understand the universe where our instruments permit is to do so.

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According to Einstein, faster than light travel is possible only if repulsive gravity existed. This is the basis of the theory of cosmic inflation.

zarathustra,
Are you talking about dark energy? The "anti gravity-like" forces that are literally tearing the universe at an exponential growth?? If so, wasn't einstein's formula the first to show mathematically that this expansion of the universe is taking place? of course he coughed it as an error and added a cosmological constant because he did not believe that the universe was expanding(energy is apparently coming out of nowhere to drive this expansion, which contradicts the energy conservation laws of newtonian physics). Later on of course, he was disproved by visual proof, and he then dubbed his mistake of adding that constant as the "biggest blunder in his life"

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I did a research project on Isaac Asimov and he states (or theorizes) that wormholes are open randomly throughout space for only fractions of MORE fractions a second. I'm guessing that if we ever want a chance to ride into one, we need to slow down time so we can see and enter the wormhole, and see where it leads to

slain, yes
or another theoretical solution that was proposed a while back. To reiterate what I said before..
The problem with a macroscopic wormhole is that it is not a static structure. What that means is that the wormhole can expand from a zero throat radius to maximum radius and back within few moments of time, so fast than even light cannot enter it. In order to maintain the maximum throat radius of the wormhole, it would need to be 'fed' with matter containing negative energy density. Such matter does not exist to our knowledge and is often referred to as exotic matter. Although we do not know how to obtain exotic matter, we have several indications that such matter may exist. For example, between two metal plates there can be field fluctuations that have negative energy density relative to field fluctuations in a free vacuum. Evaporating black holes also show negative energy density. But to obtain a finite amount of negative energy density matter is a far road ahead in terms of experimentation. However, just recently a new light has been shed on this topic. According to a Russian theorist by the name of Sergei Krasnikov, a wormhole may large and stable enough to conduct intergalatic travelling. He came up with an equation that shows that his wormholes can create its own abundant supply of exotic matter, allowing the wormhole to feed off this and making it possible for entering and exiting. But, this is still up for discussion as the theory is still fresh and many physicists are working on it to get some possible progress or to be able to refute the claim. With this in mind, we can understand that this technology may be possible in the future



we should make this thread the all purpose physics/astronomy threads im liking it !

Cheers!

how come if:
you have a flashlight
a metal box with a removable top
u flash the light into the box, then suddenly you close the box and seal it.
is there still light inside the box and once u open it the light escapes and whatever. .
i have weird questions eh?

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Originally posted by djSlain how come if: you have a flashlight a metal box with a removable top u flash the light into the box, then suddenly you close the box and seal it. is there still light inside the box and once u open it the light escapes and whatever. . i have weird questions eh?

the light escapes faster than u can close the lid u cant trap light.

how about just leaving the flashlight on in the box and waiting for the battery to run out. when the battery dies, is light still bouncing around in there or something?

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