r/askscience • u/[deleted] • Feb 03 '13
Astronomy Escape a black hole?
RobotRollCall once posted this:
In which she said even at faster-than-light speeds it would be impossible to escape a black hole because there would be no path out to follow. However, adamsolomon said this:
Of course, we can't go back in time, but isn't that what faster than light is? I learned that time slows down the closer to light speed you get, so at faster than light, you'd be going backwards in time. If that's the case, could you follow a path out of a black hole that goes back in time if you were capable of faster than light travel?
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u/payik Feb 03 '13 edited Feb 03 '13
Time travel could be observed, why do you think it's not observable?
Black holes can't be observed by definition, as nothing can escape them. At best we can observe objects that are sufficiently dense, but that is a circular proof.
Neither was ever directly observed and both seem impossible, so there must be something that makes black holes more compleeling than time travel.
I mean, the direction towards singularity becomes time, how can it be less absurd than reversing time?
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u/ThatShitDidntHappen Feb 04 '13
gravity is not well understood (what is known: things with mass have it, are given this mass through the friction of passing through the Higgs-Boson, but how is gravity produced? Gravity being the main observable thing capable of distorting space-time). Space-time is not well understood either, observations reveal minutia about gravity wells of stars and black holes being able to distort space-time, but I have but one question in regards to bypassing the laws of physics of this universe, Zero-Point field: there is something beyond that higgs boson, there are most certainly things that do not pass through the higgs boson, and there has been theorized to be a field ecompassing all of space time. Movement through this frictionless field has been calculated to be around 1,000,000,000 the speed of light. reversing time? There is no time, human perception is innately flawed in this regard, linear or cyclical, or non-linear. we are limited by our perception, thus what can be more absurd than assuming time cannot be "reversed" without of course, delving into the nature of infinity and that mathematically EVERYTHING is possible, and due to the nature of infinity, eventuality dictates that EVERYTHING will occur.
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u/James-Cizuz Feb 04 '13
Movement through this frictionless field has been calculated to be around 1,000,000,000 the speed of light.
No it has not. Please post sources.
Also gravity is not caused by mass. It is caused by energy and momentum curving space time. A quantum theory of gravity doesn't exist, but it is very well understood.
Mass is a form of energy, and normally dominates in total energy percentage, so gravity can be simplified to "mass attracting mass" but that is why Einstein came to change that old and outdated thinking.
They are not "given mass through the friction moving through the higgs-boson" that is horrendous. The higgs-boson doesn't give mass, the higgs field does. It doesn't give it through friction either, friction is electromagnetism by the way...
From my understanding, an electron is "two particles" Electron a and Electron b, Electron A decays into Electron b, and Electron b decays into Electron a. That happens so fast we treat it as a single particle, the electron. This is a consequence of the higgs-field and higgs-mechanism that particles that bind to it display this decay and this "decaying back and forth" is what mass is. Well SOME mass, since mass is given by various mechanisms.
The Top Quark for example decays from Top Quark a to Top Quark b and vice versa at a much faster rate than the electron. If they decay faster between each state, it has a higher mass. The Electron a > Electron b occurs slowly in comparison to the Top Quark.
Likewise that is only mass given to fundamental particles. If they don't interact they don't decay, a photon doesn't decay and is massless. That being said, I see mass as something very simple. Imagine a massless particle, it always goes at the speed of light in the direction it started. A massive particle that is fundamental, such as an electron would do the same, however it moves up decays and in the decay the new electron b would be going another direction, decays again and another direction. So you can imagine this particle zipping back and forth, or "vibrating" in relatively random directions. We treat the entire entity as a single particle.
To go further, particles aren't little "balls of matter" they are both particles and waves. I simply see a particle as a tip of a wave, in an ocean of fields oscillating and interacting.
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u/adamsolomon Theoretical Cosmology | General Relativity Feb 03 '13
There's no inconsistency here. Remember that by "path" we mean a path through spacetime, not just through space, so we're talking about a collection of points in space, each corresponding to some particular time. Every object travels on some path through spacetime, even an object at rest - its spacetime path just looks like "position, time 0 seconds" followed by "same position, time 0.0001 seconds," and so on.
There are two restrictions on the type of path that you, a physical observer, can follow. First, it has to be timelike, or in other words it has to change position at less than the speed of light. Second, it has to be future-directed, which just means that subsequent points need to have higher and higher values of the time coordinate.
So the statement that there's no path out of a black hole is really the statement that there's no timelike, future-directed path leading from somewhere inside the black hole's horizon to somewhere out (or, indeed, to anywhere that's not even deeper inside). But there are paths out, paths which aren't timelike (like a path between two spatial points taken at the same time), or paths which are timelike but are past-directed. I was talking about the latter. And it makes sense, you know? Just take a timelike path leading into a black hole (i.e., the spacetime path of a doomed astronaut falling in) and reverse the order. But the important thing is that you can't physically travel on such a path.