311–320 of 502 posts
Does this mean an actual truck, a vehicle? Did they accidentally hurt someone?
I liked this quote: The future for the dark side looks bright.
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My intuition is that this is unlikely, but I'd love to see someone do the math. Given the scale of interstellar distances, any locations on our planet (and even in our solar system) are going to effectively function as a single point. Given arbitrarily-accurate measurement, it could work, but I'd bet physical limitations will prevent that from being a possibility. To my mind, it'd be roughly like trying to triangulat…
It would work. The delta-t is a few miliseconds. This gives enough precision for a decent estimate of the direction of the signal. Now estimating the distance is a different matter.
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The predictions for the LIGO detection rate are very poor. They're based on a sample of just a handful of binary pulsars observed in our Galaxy, which would produce NS-NS mergers. The BH-BH merger rate is almost totally unconstrained, although it is generally thought to be less than the NS-NS merger rate. So the fact that a BH-BH merger was the first detection, and the fact that it was detected so soon after the sens…
I recall reading some years ago that gravitational wave would be used to prove multiverse theory. How would that scale compared to bh-bh or ns-ns mergers? Also, have read today that this discovery backs inflationary theory, how so? It seems highly unlikely that they could say a specific bh-bh merger was the cause. It seems implied they are triangulating the source, with two detectors?
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The amount of energy needed to transmit via a gravitational wave is INSANE. It would involve very rapidly accelerating and decelerating a black hole / neutron star. While it might be possible to do this, it's not within the realm of something we could accomplish without several orders of magnitude technology improvements, and possibly may not be physically possible at all (moving object that heavy that quickly might…
Even if it were possible, what sort of crazy alien would it take to burn 3 solar masses of negentropy to basically run a ping, compared to the amount of data that could be transmitted with electromagnetic waves with 3 solar masses of negentropy? It's literally dozens of orders of magnitude in difference. Any aliens that are that bad at engineering probably aren't going to grow to the point that they can shake neutron…
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My intuition is that this is unlikely, but I'd love to see someone do the math. Given the scale of interstellar distances, any locations on our planet (and even in our solar system) are going to effectively function as a single point. Given arbitrarily-accurate measurement, it could work, but I'd bet physical limitations will prevent that from being a possibility. To my mind, it'd be roughly like trying to triangulat…
It definitely would work. The distance to the event is irrelevant, it's the light travel time between the detectors compared to the accuracy with which you can pin the event down in time that matters. The light travel time across the Earth is of order a hundredth of a second, which is a significant fraction of an event that takes ~ a tenth of a second. However, the error ellipse will probably be quite larg, and given…
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>> that shortly after the detector came online we just happened to observe the exact moment a billion years ago that two black holes collided? Counterintuitive, but yes. Because it happened billions of years ago, it happened a long long way away. The sphere of objects billions of years away/ago is far larger than those closer to us. So such a detector should be detecting exponentially more very old objects than new o…
If one event happens 1B years ago 1B light years away and another event happens at .5B years ago .5B light years away... how would we know there are two events?
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Here's my re-statement of this confusion, isn't everything we can experience embedded in time-space, including the LIGO experiment itself? So how is there any relative shift allowed to be detected when everything we know is fundamentally intrinsic to time-space? That is, I too would appreciate having this mis-conceptualizing, of mine, cleared away.
Another re-phrase: how can we detect that space has stretched out if all of our rulers also get stretched by exactly the same amount? The answer is that we have a ruler that doesn't get stretched in this way: light. The speed of light is a constant dictated by the laws of physics; stretching out our flashlight to twice its normal size wouldn't make the light it emits go twice as fast. So if you just measure the time…
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Here's my re-statement of this confusion, isn't everything we can experience embedded in time-space, including the LIGO experiment itself? So how is there any relative shift allowed to be detected when everything we know is fundamentally intrinsic to time-space? That is, I too would appreciate having this mis-conceptualizing, of mine, cleared away.
Another re-phrase: how can we detect that space has stretched out if all of our rulers also get stretched by exactly the same amount? The answer is that we have a ruler that doesn't get stretched in this way: light. The speed of light is a constant dictated by the laws of physics; stretching out our flashlight to twice its normal size wouldn't make the light it emits go twice as fast. So if you just measure the time…
Can we compute the strength of a static gravity field we are inside, by measuring the time that light takes to propagate through it?
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If the massive gravitron was leaving a black hole it would be slowed by the black hole's gravity. (1) We should see this as some inconsistency in how gravity scales with the mass of a black hole. The larger ones would have proportionately greater 'drag' on leaving gravitrons, pulling more in. (2) If they are massive, and therefore subject to slowing, shouldn't gravity waves leaving a black hole be subject to some sor…
(None of my points below say the graviton is massless, just that it's not crazy. As another post says, this new observation probably confines the graviton mass to be less than 10^-55 grams) > If the massive gravitron was leaving a black hole it would be slowed by the black hole's gravity. A graviton wouldn't be able to escape a black hole. A photon can't, and it's massless. The gravity of a black hole is actually a s…
But isn't the curvature of spacetime around the black hole supposed to be the effect of its interaction with the graviton??
Is this where the translation from GR -> QM breaks down?
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That always confused me. We have an Oort cloud, whose members we cannot resolve very well/at all. Why do we assume only our star has such a thing? If all stars did, that isn't enough mass to explain dark matter?
The total mass of the Oort cloud is guessed at (3×10^25 kg), or about five Earth masses. With dark matter, we are talking about roughly 5.6x the amount of the total solar system mass. The Oort could would need to be about 371,691x more massive than it is. https://www.wolframalpha.com/input/?i=mass+of+the+solar+syst...
So we might be here only because our solar system is surrounded by an unusual amount of nothing.