I have read that black holes might be viewed not as objects at all but as extreme spacetime curvature
Is that correct or have I perhaps misconstrued?
Is that correct or have I perhaps misconstrued?
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The idea of quantisation of photon energy arose from a need to explain observations and is frequently misinterpreted.I remembered your post just now and want to ask you how it can be known that the energy levels can take any value?
Our best explanatory model is that charge is indeed quantised, as are the electron energy levels in any given atom, but a different atom can have arbitrarily different energy levels (which is why we can distinguish them spectroscopically) so "energy" is a continuum.
Thus there is no a priori reason to suspect that "space" or "time" is quantised.
Come to think of it, Heisenberg pretty well contradicts the idea of granular spacetime. As you decrease the uncertainty of your position measurement, so you increase the indeterminacy of your momentum. If both space and time were granular there would only be a finite number of discrete values of both, so indeterminacy would be limited and we'd be back to the impossible orbiting electron model of an atom.I hope you are right as that would put my question to bed.
Changes to masses inside a black hole emit gravitational waves that cannot leave the black hole for the same reason light cannotWhat ,then, is the effect of changes to the distribution of mass inside a BH? Anything? Do we know?
. I suspect geordief likes these continued discussionsYes he does.It takes me a lot of effort to follow the replies ,though after my question has been answered in the main.
I can see why the mechanisms whereby the brain processes reality (which ,to my mind includes all kinds of abstract and not simply functional processes) ..I can see how fascinating and absorbing that must be to anyone involved.I think about this question from time to time. It is quite interesting.
(as an aside ,does the thinking process have to follow the same laws and are our minds forbidden to imagine possibilities at some deep physical level no matter how unrestrained our imagination can appear to us? Even imagination would be tethered?)
Yes, there is a lot of evidence that imagination is tethered/correlated to a chemical process in the brain, but it is only said to be a correlation. They are not necessarily interchangeable entities. For example, the image of an orange in my brain is only known to be correlated to a process in my brain; it is not known to be the same thing as the process in my brain. This is at least how science is dealing with the relationship between body and mind.
Anyways, this means that there is no telling what thoughts, theories or answers we may think of. Our imagination would be limited only by how many possible processes in the brain there can be.
One could say that a 'thing' is something to which you can point, and also be able to point to not-the-thing.Yes, that's better.
So I can point to both an apple and the table on which it rests, the latter qualifying as not-apple.
Language is a source of a lot of misguided intuition about such topics. It leads to assumptions for which there isn't any actual evidenceOh,yes.
Why is the Universe not a thing ? isn't it every-thing ? which is also a thing ?I think the universe is only a "thing" if you can point to it some way.Everything spins, but the universe isn't a thing. An object without a bounded size cannot meaningfully spin.
Ewe spin me right round quickly,
tight round, getting dizzy,
ralph a one pound ground round moundSpin in relation to what?Spin is absolute, and need not be in relation to any particular frame, although something's angular momentum is at least relative to an axis, but angular moment and spin (RPM say) are different things.
doesn't matter too much if gravity was really "caused" by something else. "Cause" is a very subjective term anyway
Perhaps a related question - would hypothetical gravitons be absorbed by a black hole?How might we (in theory) detect that a graviton had interacted with the actual singularity** of a black hole?
- If a black hole is (say) 10km across
- And the gravitational waves have a wavelength of (say) 30,000km?
I expect that wavefunction of the gravitons allow you to calculate the probability that a particular graviton is found at a particular point in space
- There is a finite probability that an individual graviton will impact the event horizon of the black hole
- Since there are so many gravitons in a gravitational wave, some of them will impact the event horizon, and be absorbed.
The same argument applies to photons in an electromagnetic wave with a wavelength of 30,000km.
Nothing escapes a black hole, which is not a star, nor even a location in coordinate space.(with usual apologies in advance for probable misunderstanding) How then can we say that there is expected to be a Black Hole at the centre of every Galaxy?
Hi.That was very funny
Could someone clarify how these things work? Whenever the posts start of with "Donald presented this...." or "Donald wrote in to ask this.....", then we're never going to get any interactivity with Donald are we?
So am I right that if I asked Donald to clarify a few details, then I'd be wasting my time?
Also when people write a reply, such as Origin has just done, will Donald ever see it, hear it or care about the reply in the slightest? To phrase the question another way: What is the point of replying to these things? Would Origin have done just as well to shout his last reply down the street on a quiet night?
" Is life built into the fabric of the Universe?"That is a 10 point penalty for over literalism.
Well it's not built outside of the fabric of the universe, is it?
The entire universe seems to have been an accident. You can invent any kind of universe you like, including one where nothing changes so nothing can evolve. However if it is finite it must have a beginning and an end, so it must contain some element that initiates change. We therefore have to define a universe of infinite temporal and physical extent for life not to evolve.Oh,I am finding that confusing to follow.We know life did evolve .So are you saying that we must define a universe of finite temporal and physical extent to fit that observed outcome ( the outcome of life actually having evolved)?
"The entire universe seems to have been an accident"...
Thanks,I think I understand that now.Do they travel as as expanding sphere?Gravitational waves travel in all directions at light speed, so yes in that sense. A given wave isn't spherically symmetric (rings as you put it) any more than a propeller in the air creates spherical waves. It creates more like spirals, strong in the orbital plane and weakest along the axis of rotation.QuoteIf so ,is the total energy level on each concentric ring of the sphere the same no matter the distance from the source measurements are made?There are not concentric rings, and the energy is most concentrated in the orbital plane. If you had an instrument capable of measuring Earth's gravitational waves, it would be stronger out by Neptune's orbit compared to the same distance but along the rotation axis of our solar system.