How to bend spacetime, cause an intersection, and pass through?

[GreekTTC]

...or is it already ready and waiting for us to figure out how it works?

 

Since spacetime has been theorized to be multidimensional (4 or even 5 dimensions), I was thinking about the "piece of paper" example where you bend a piece of paper without creasing it and touch two points together. It has been said that if we can do that to spacetime, we might be able to pass through to a distant part of outer space (aka, wormhole, correct?). And then I was also thinking about the "bowling ball on a stretched out sheet" example where a marble dropped on the sheet will *gravitate* toward the bowling ball (aka, gravity, correct? ...according to Mr. Einstein).

 

Now put those together. Since spacetime is multidimensional, maybe we don't need to bend anything. Maybe we don't need any kind of new "spacetime-bending" device or any of that... maybe the point where spacetime bends and meets is...drum roll please...a black hole. Since spacetime is multidimensional and all...

 

Now I'm no mathematician, but let's say a black hole is where spacetime meets and it might be possible to pass through somewhere near a black hole. Maybe it would be right around the event horizon...right before the black hole's power will start to suck you in. Or maybe it IS the center of a black hole?!?!

 

I propose a new theory, haha...I'll call it "reorganization." What if when something passes through a black hole, it's put back together on the other side the same way it was before it went in, it's just in a different place, maybe thousands of light-years away from where it went into the black hole. Doubt it, but it's fun speculation. I just don't think humans are going to get ANYWHERE important via solar sails or any other means that attempts to travel using speed as a means. The distances are just too vast.

 

Haha...I amuse myself. But I want to know how space travel to very distant places is possible before my time on this Earth is done, dammit! There must be a few alien races out there with the know-how. Anyone got their phone number?

 

Blabbering over =D

[Tormod]

I propose a new theory, haha...I'll call it "reorganization." What if when something passes through a black hole, it's put back together on the other side the same way it was before it went in, it's just in a different place, maybe thousands of light-years away from where it went into the black hole.

 

You write both "near" and "through" a black hole, which are of course hugely different (as you probably know). But if you are imagining that anything that travels into a black hole pops up somewhere else in the universe...then what is inside the black hole? All the content that was supposedly in the black hole would be somewhere else, and there would be no black hole.

 

Haha...I amuse myself. But I want to know how space travel to very distant places is possible before my time on this Earth is done, dammit! There must be a few alien races out there with the know-how. Anyone got their phone number?

 

Sure...but it's stored in my black hole computer and I have problems accessing it. :xx:

[UncleAl]

I was thinking about the "piece of paper" example where you bend a piece of paper without creasing it and touch two points together.

Kip Thorne's wormholes created by request from Kurt Vonnegut for a plot twist. Despite initial enthusiasm and a lot of published physics, wormholes are forbidden.

 

And then I was also thinking about the "bowling ball on a stretched out sheet" example

Draw a triangle on the stretched membrane. Add its internal angles. You get a Euclidean 180 degrees exactly. Add the central mass. Add its internal angles. You get less than 180 degrees due to the central pucker. In the gravitational case the triangle's internal angles would add to more than 180 degrees, e.g., the LATOR experiment. You are wrong.

 

What if when something passes through a black hole,

The Forever War by Joe Haldeman If you've got to get from here to there in a hurry, sf or sci-fi has considered it even if arXiv.org has not. Here'a little hint from Uncle Al,

 

http://www.google.com/

http://groups.google.com/

http://scholar.google.com/

http://arXiv.org/

http://www.scirus.com/

http://scitation.aip.org/

http://www.crank.net/

 

Do your chair parade before making a public declaration of heterodox science. If you post something massively, ah, regrettable at least you will have literature citations to ameliorate the sting.

 

I want to know how space travel to very distant places is possible before my time on this Earth is done

http://www.mazepath.com/uncleal/ss1.jpg

You wouldn't get past the cavity search.

 

Galactic travel is not difficult. The vehicle goes back in time as it goes forward in space. You can get from any here to any there essentially instantly, and you need not go fast to do it.

[GAHD]

Not exactly a 'new' idea, problem with black holes is that time & space might just be inverted once you pass the event horizon.

 

More likely that wormholes don't and cannot exist, sad to say.

 

Galactic travel is not difficult. The vehicle goes back in time as it goes forward in space. You can get from any here to any there essentially instantly, and you need not go fast to do it.

source?

[Erasmus00]

Not exactly a 'new' idea, problem with black holes is that time & space might just be inverted once you pass the event horizon.

 

More likely that wormholes don't and cannot exist, sad to say.

 

source?

 

The other problem with black holes is that tidal forces would rip you apart long before you got through the event horizon.

 

And, yes, it is unfortunate that wormholes, the alcubierre "warp drive" metric and other faster than light travel solutions require negative energy density. However, all is not lost, as the Casmir effect, and others, seems to imply that negative energy density is possible, if rare.

-Will

[CraigD]

:( GreekTTC, I think you’re taking the phrase “black hole” too literally. They’re not “holes in space” in the sense that a doorway is a hole in a wall, but rather just concentrations of ordinary matter so great that physical law in their proximity is stange and counterintuitive, so much so that there has been and continues to be controversy among physicists about the precise nature of that law.

 

A prediction of General Relativity that most folk agree has been confirmed by observations is that clocks - a physics term for anything that can measure time, including a human being or a photon of light – run slower when close to a massive object than when far away. The math of “gravitational time dilation” around a black hole isn’t complicated: t = tO/( 1 – rEH/r )^.5, where t is the amount of time measured by a distant observer, t the amount measured at a distance of r from the center of the black hole, and rEH the distance of the black hole’s event horizon from its center. For example, if you approach to within 1,000 km of the event horizon of a black hole with an rEH of of 10,000, t = t0/ (1-10000/11000)^.5 =~ 3.32*t0, that is, time passes 3.32 times a quickly as normal.

 

Notice that, as r approaches rEH – that is, as you approach the event horizon of the black hole, the time dilation ratio gets greater and greater, approaching infinity. So GR predicts that an person on spaceship approaching a black hole would return to its starting point to find that much more time had passed there than on the ship. If the event horizon was actually reached, an infinite amount of time would have passed in the outside universe!

 

This suggests that, even if black holes somehow link distant points in space – not at all a well accepted conjecture – and one could somehow solve the engineering problems of withstanding the infinite (or at least very big) physical stress to be found near a black hole, you’d arrive at a destination infinitely far in the future, where presumably all stars would be extinct, and ordinary matter decayed, etc. Rather than getting to your destination quickly, you would have gotten there infinitely slower than the slowest possible trip via a conventional spaceship, such as one of the Voyager probes!

 

For this among other reasons, few science-literate folk have much hope that black holes offer much hope for space travel. It still makes for good SF, though – it’s a central feature of Fred Pohl’s novel “Gateway”, which won both the 1978 Hugo and Nebula awards, in which a spaceship crew is rescued from the brink of a black hole many years after they accidentally approach it.

 

:D If you really want to travel to distant stars and planets, look toward designing spacecraft that can accelerate to very high fraction of the speed of light, here, the accepted physical theory (Special Relativity) predicts: t=t0/(1-v^2/c^2)^.5, were t is time measured on the ship, t0 the time measured at its origin and destination, v its speed, and c the speed of light. For example, for v=0.999 c, t=t0/(1-0.999^2)^.5 =~22, that is, a 22 light-year-long trip would appear to someone on the ship to take less than a year. Over 22 years would pass at your destination, so you wouldn’t have to worry about stars having burned out, etc.

 

If you’ve given a lot of thought to what’s involved in getting a ship to go this fast, you’ll likely eventually reach the conclusion that the key to this is to not try and generate the required power on the ship itself, but at a massive facility in its system of origin. You’ll likely wind up with something like this, a design described by engineer, SF writer and futurist Robert Forward.

 

:) This really belongs in the spaceflight forum, no?

[GreekTTC]

Thanks for the info all, save for the conceit of the narcissist.

 

CraigD, that's a lot of awesome information. Thanks.

[Boerseun]

Black holes are where God divided by zero.

[GAHD]

nice quote boerseun, now can you name who said it without a google search?:)

[Jay-qu]

Hawking? Kaku?

[GAHD]

And the answer is.... Steven Wright*

 

 

[Aki]

Speaking of black holes... why don't NASA or someone just send something inside a black hole and see what happens?

[GAHD]

hehe, you might want to think a bit about light years Aki.

[CraigD]

why don't NASA or someone just send something inside a black hole and see what happens?

1. They’re a bit hard to find. The only reliable way to find one is when it’s a collapsed star orbiting a un-collapsed star, which throws off a gawdawful amount of x-rays and energetic plasma. So the closest one NASA or anybody knows about may not be the closest one there is, just the closest one we know how to detect. At present, that one – Sagittarius V 4641 - is about 16,000 ly in

 

2. As GAHD notes, that’s a long way. Barring some incredible advance in spaceflight technology, it means you wouldn’t get to see what happens for at least 32,000 years. Realistically, given the most optimistic performance of any proposed near future spaceflight tech driving a ship to a max of about .1 c, the wait would be about 192,000 years. I don’t think NASA’s that patient.

 

3. “Gawdawful amount of x-rays and energetic plasma” make black holes difficult to approach without getting reduced to energetic plasma yourself. Even a black hole that isn’t eating it’s companion star and generating all this light and particle energy is still thought to be leaking enough Hawkings radiation to reduce a probe to subatomic debris.

 

4. As I mention upthread, General Relativity, which a couple of generations of high-quality observation has taught us to believe in, tells us that, due to gravitational time dilation, it would take an infinite amount of time for the probe to travel the last little distance to the black hole’s event horizon.

 

5. No one’s sure, and no well-tested theory can predict, how anything behaves inside a black hole. Most informed folk are pretty sure ordinary stuff like atoms are impossible. There’s a strong suspicion that the laws governing matter/energy and space/time are very weird there. A probe inside a black hole might have to rediscover many practical laws of Physics before it would know how to do anything.

 

6. A final problem to a trip inside the event horizon of a black hole is that, as the name and at least one bad movie suggests, it’s difficult to get any data out once you’re in. Surprisingly, this is one problem that could probably be solved, since old, reliable Quantum Mechanics predicts that quite a bit of mass/energy can actually be “tunneled” out of a black hole in the form of Hawkings radiation, using a scheme resembling a scaled-up scanning tunneling microscope. If you’re really clever, you could use this trick to get around problem #4, too.

 

So, just from what I can think up, a black hole mission faces 3 hard problems (#1,2,3), 1 impossible-according-to-theory-but-trickable-by-another problem (#4), 1 weird problem (#5), and 1 not-too-hard-once-you’ve-rediscovered-the-laws-of-Physics problem (#6).

[Erasmus00]

 

 

3. “Gawdawful amount of x-rays and energetic plasma” make black holes difficult to approach without getting reduced to energetic plasma yourself. Even a black hole that isn’t eating it’s companion star and generating all this light and particle energy is still thought to be leaking enough Hawkings radiation to reduce a probe to subatomic debris.

 

6. A final problem to a trip inside the event horizon of a black hole is that, as the name and at least one bad movie suggests, it’s difficult to get any data out once you’re in. Surprisingly, this is one problem that could probably be solved, since old, reliable Quantum Mechanics predicts that quite a bit of mass/energy can actually be “tunneled” out of a black hole in the form of Hawkings radiation, using a scheme resembling a scaled-up scanning tunneling microscope. If you’re really clever, you could use this trick to get around problem #4, too.

 

 

Hawking Radiation is proportional to 1/M^3, I believe. So Astronomical black holes have a very low effective temperature, (a solar mass black hole has an effective temperature of about 1/(10000000) Kelvin) so Hawking radiation shouldn't really be a problem. Mini black holes, on the other hand, have higher theoretical temperatures.

 

As to tunneling out of a black hole, the mechanism for Hawking radiation is virtual pair production near the event horizon. While this does convey some information about what got thrown into the black hole, its in such a horribly scrambled form as to be essentially useless.

-Will

[CraigD]

Thanks for catching me misunderstanding Hawking radiation.

 

Per the Wikipedia article “Hawking radiation”, I think radiation power is proportional to 1/M^2, but your point remains correct. I was flat-out wrong about this radiation being significant around a single collapsed star black hole.

 

I was also confusing the concept of Hawking radiation and quantum tunneling. What I meant to suggest was using some far-out scheme to get some particles’ quantum wave functions so smeared-out that, although the expected positions given by the wave functions are inside the event horizon, a measurement would detect some on the outside.

 

Mixing Quantum Mechanics and General Relativity is weird, and, strictly speaking, impossible. My personal position on this incompatibility is that, being a classical theory, GR gives only empirical, approximate predictions, which QM, a fundamental one, gives exact predictions. Somehow, the Standard Model will have to be expanded to include at least one gravity boson (“graviton”), at which point “hard walls” to wave functions, such as black hole event horizons, will be banished, and what will be left will be a dizzyingly complicated but fundamentally tractable Feynman diagram of interactions, some of which will describe a means of transmitting data from a black hole.

[Qfwfq]

Speaking of black holes... why don't NASA or someone just send something inside a black hole and see what happens?

Most of what happens is beyond the event horizon. Especially what is less predictable by GR.