31–40 of 45 posts
Earlier quoted context omitted.
In addition to the other explanations given, it won't affect us presently because it already happened a long time ago.
If I send a slow, waddling mobster to go break your kneecaps, are you affected when I give the order or two weeks later when Guido knocks on your door?
Earlier quoted context omitted.
If I send a slow, waddling mobster to go break your kneecaps, are you affected when I give the order or two weeks later when Guido knocks on your door?
Only if gravity moves at the same speed as light, right? It sounds like we've been observing energy emissions (light) rather than directly observing it's gravitational impact on us.
Earlier quoted context omitted.
Only if gravity moves at the same speed as light, right? It sounds like we've been observing energy emissions (light) rather than directly observing it's gravitational impact on us.
Gravity has to move at the same speed as light. If it didn't it would cause time paradoxes.
Earlier quoted context omitted.
This includes the effects of general relativity. As long as the mass is the same, the orbits of planets will remain the same.
According to wikipedia[1] the converse of the Shell Theorem is (nearly) true: Suppose there is a force F between masses M and m, separated by a distance r of the form F = Mmf(r) such that any spherically symmetric body affects external bodies as if its mass were concentrated at its centre. Then what form can the function f take? The form of f allows Newtonian gravity but not Einsteinian. [1] http://en.wikipedia.org/w…
Considering the lightyears involved, I assume this means we'll see it in 2013?
That's correct. But never forget the idea of a "now" is deeply tied to a "here".
If so, what kinds of implications would this have to us? Is this quasar radiation merely an observable thing, or could it disturb communications or something along those lines?
Edit: no doomsday paranoia implied. :-)
Earlier quoted context omitted.
That's correct. But never forget the idea of a "now" is deeply tied to a "here".
Implying whatever happened so many thousand years ago will have an impact here at about the same time we observe it happening from here? (I.e. light coming from that time and direction arrives here at about the same time as whatever implication this has to us does.) If so, what kinds of implications would this have to us? Is this quasar radiation merely an observable thing, or could it disturb communications or somet…
In other words, “it happened n years ago”, like “it’s happening right now”, isn’t defined by itself; it only makes sense for given values of here and there.
This comes out of special relativity and is closely connected with the fact that nothing, not even photons, can move faster than a certain speed.
Earlier quoted context omitted.
Implying whatever happened so many thousand years ago will have an impact here at about the same time we observe it happening from here? (I.e. light coming from that time and direction arrives here at about the same time as whatever implication this has to us does.) If so, what kinds of implications would this have to us? Is this quasar radiation merely an observable thing, or could it disturb communications or somet…
I think that’s the implication, but it goes even further than you say: because of the relativity of simultaneity (see Wikipedia), there is no absolute yardstick of the timeline. In other words, “it happened n years ago”, like “it’s happening right now”, isn’t defined by itself; it only makes sense for given values of here and there . This comes out of special relativity and is closely connected with the fact that not…
Can somebody explain why the black hole at the center of our galaxy is called "Sgr A*"? Is there some system behind the name or are astronomers just like programmers in naming stuff (it took me a while to figure out how to pronounce nginx >:().
Sgr is short for Sagitarrius, a constellation. If you mark off the boundary of Sagitarrius, Sgr A* would be in that region. The black hole itself does not have the name, but rather the radio source associated with it. (conjecture alert)I'm not sure where the * comes from, but I believe the A is associated with the fact that Sgr A is a super nova remnant. Supernova are typically named "SN [year] [alpha]" where [year]…
Hah, I'd sort of known what the Messier catalog was, but you inspired me to look at its Wikipedia page[1]. Apparently Charles Messier was looking for comets, and was tired of getting distracted by things that weren't comets. M1 is the Crab Nebula[2].
This amuses me.
[1] http://en.wikipedia.org/wiki/Messier_object [2] http://en.wikipedia.org/wiki/List_of_Messier_objects
That may be about to change, however. Astronomers have spotted a cloud of gas with a mass about three times that of Earth that's on a trajectory that will have it pass close to Sgr A in 2013* If this is for real, I am ridiculously humbled by the power of modern astronomy. It's pretty damned amazing to me that we have the ability to detect the location, dimension, and trajectory of a mere 3 earth-masses of thin, amorp…
Feel free to correct me if someone has read the article.
[1] http://www.nature.com/nature/journal/vaop/ncurrent/full/natu...
[2] http://www.eso.org/public/teles-instr/vlt.html
[edited for mistake]