Considering the lightyears involved, I assume this means we'll see it in 2013?
Think of it as the "egocentric" rule of astronomy: always describe things from the perspective of the observer (you), not from the perspective of the agent.
The Milky Way's black hole may spring to life in 2013
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Re: The Milky Way's black hole may spring to life in 2013
#22Could someone explain the implications of all this in laymen terms? Are we in deep shit?
No.
But the accretion disk might appear visible to various instruments.
Basically, we will see the exact location of the black hole for the first time directly. Not the collapsar itself, of course, but the swirling disk surrounding it.
Re: The Milky Way's black hole may spring to life in 2013
#23Earlier quoted context omitted.
The black hole is estimated around 4 million solar masses, the gas cloud around 3 earth masses.
So by "spring to life" the writer meant "we may, if we're lucky, finally see a glint of something". It's very exciting, yet the writer put it in terms that will scare the living hell of any uneducated person like me. Glad there's always HN.
I was thinking of the exact same thing.
It's ironic when a piece of writing tries to present you with factual information begins with a deceiving title, all in the name of attention grabbing.
Re: The Milky Way's black hole may spring to life in 2013
#24Considering the lightyears involved, I assume this means we'll see it in 2013?
Presumably, yes. It would be odd for the astronomers to use two different temporal points of reference; time of observation is the only time that matters. Plus, any excitement on the part of astronomers would be super pointless if they had to wait another 24824 years to observe it.
From the point of view of a photon originating in that gas cloud, it was emitted by an electron in the gas cloud and absorbed by an electron in the telescope sensor at the exact same instant.
Re: The Milky Way's black hole may spring to life in 2013
#25Considering the lightyears involved, I assume this means we'll see it in 2013?
Presumably, yes. It would be odd for the astronomers to use two different temporal points of reference; time of observation is the only time that matters. Plus, any excitement on the part of astronomers would be super pointless if they had to wait another 24824 years to observe it.
On the other hand it would be impressive if they correctly predicted it from 24-millenia-old data.
Re: The Milky Way's black hole may spring to life in 2013
#26Could someone explain the implications of all this in laymen terms? Are we in deep shit?
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?
Re: The Milky Way's black hole may spring to life in 2013
#27Earlier 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?
Good point, I retract my comment :)
Re: The Milky Way's black hole may spring to life in 2013
#28Can 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 >:().
It stands for "Signor A*", in order to show it proper respect. I'm glad to see that in this crude age, our astronomers still have class.
Re: The Milky Way's black hole may spring to life in 2013
#29Earlier quoted context omitted.
This is true for Newtonian gravity, but only approximately true for general relativity (or so I understand it).
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/wiki/Shell_theorem#Converses_and_gen...
Re: The Milky Way's black hole may spring to life in 2013
#30Earlier 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…
Interesting. However, I would have thought that planets are far out enough that classical is accurate enough. This sort of thing is why I specified planets as opposed to orbits in general.