Message boards :
Science (non-SETI) :
Black Holes part 2
Message board moderation
Previous · 1 . . . 11 · 12 · 13 · 14 · 15 · 16 · 17 . . . 35 · Next
Author | Message |
---|---|
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
Please remember that neutron stars and black holes are the remnants of massive stars ... Good brief summary, thanks. Note that for a neutron star and for any greater collapse, the source elemental composition is likely irrelevant. Whatever different types of atoms you may have started with, are now all subatomically smashed into mainly neutrons ("neutronium") for a neutron star, or whatever subatomic or energy soup forms for further collapse/compression of matter when forming a black hole. Whatever, all a very heavy weirdness! Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
bluestar Send message Joined: 5 Sep 12 Posts: 7224 Credit: 2,084,789 RAC: 3 |
I am watching the mentioned YouTube videos right now. So, by means of defining gravity you are able to describe a four-dimensional space rather than the three-dimensional space which we are able to see and observe. Isn't gravity indirectly or implicitly defined by means of Einstein's E=mc2 then? Gravity is assumed to be a force on its own, but it is the result of the presence of matter, something which is thought of as being mass and not energy. Again, the notion of time itself is still not present at all. |
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
... Isn't gravity indirectly or implicitly defined by means of Einstein's E=mc2 then? Gravity is assumed to be a force on its own, but it is the result of the presence of matter, something which is thought of as being mass and not energy. For all we know, that which we call "time" may be just an "effect" of something else, just as gravity appears to us as an effect of mass-and-or-energy. Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
Good point Hopefully not a singularity! ;-) Meanwhile, where oh where has our 'expert' gone? Hope he's not gone the way of Dr Hans Reinhardt in testing out his conjectures...? :-p Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
Lynn Send message Joined: 20 Nov 00 Posts: 14162 Credit: 79,603,650 RAC: 123 |
According to NASA, the discovery of monster black holes were important pieces of a puzzle first unveiled in 1962. Interesting article. http://www.hngn.com/articles/12097/20130911/nasa-telescope-captures-10-monster-black-holes.htm NASA Telescope Captures 10 Monster Black Holes NASA link: http://www.nasa.gov/mission_pages/nustar/news/nustar20130905.html#.UjFiDX9IHSc ____________________ The universe wastes nothing, it's simply transferred. Lynn |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
Rare star probes supermassive black hole Thanks for that one, rather interesting and a good interesting addition to the story for the black hole at the centre of our galaxy. Also, a nicely written accurate article. Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
So... To break this down into smaller more tasty chunks ;-) infinite acceleration frame (infinite gravity). [...fluff points snipped...] Just the one point from all that: For there to be "infinite gravity" (due to infinite mass) anywhere in our universe, by the very nature of "infinite", we would all already have instantly succumbed to such an infinite force and already instantly be 'gobbled up' to not exist. Such is the effect of infinite. Contrary to that, we seem to exist. Hence, keep all this simple by not suffering any infinities? Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
cov_route Send message Joined: 13 Sep 12 Posts: 342 Credit: 10,270,618 RAC: 0 |
Martin, the question is a tricky one. Things at the event horizon are highly relativistic, whereas our natural intuition is Newtonian because that's the world we live in. It turns out that one measure of gravity at the EH is indeed infinite, but it also turns out that you can pass through the EH unscathed if the black hole is big enough to limit the tidal forces. Sadly my background is not broad enough to let me explain clearly what is going on. The way I think of it, and I'm not sure it's 100% right, is that gravity goes to infinity, but time dilation (red shift) goes to zero, so you have an infinity x zero situation. Turns out the limit of that quantity is neither infinity nor zero, but a well defined value in between. Note I am talking about the proper time, the time experienced by the observer crossing the EH, not a far-away observer. The far-away observer sees the EH crossing traveler slow down more and more, and never actually reach the point of infinite gravity. One thing I wonder about is the incoming starlight that EH crosser sees. I wonder if it gets highly blue shifted into the gamma spectrum so that the traveler gets zapped to oblivion by it. |
cov_route Send message Joined: 13 Sep 12 Posts: 342 Credit: 10,270,618 RAC: 0 |
I was trying to learn more about space-time diagrams so I could understand what one looks like at the event horizon, and I ran across this: Penrose diagrams are frequently used to illustrate the space-time environment of black holes. Singularities are denoted by a spacelike boundary, unlike the timelike boundary found on conventional space-time diagrams. This is due to the interchanging of timelike and spacelike coordinates within the horizon of a black hole (since space is uni-directional within the horizon, just as time is uni-directional outside the horizon). http://en.wikipedia.org/wiki/Penrose_diagram#Black_holes All to say intuition is the first thing that breaks down in the vicinity of a black hole. |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
cov_route Send message Joined: 13 Sep 12 Posts: 342 Credit: 10,270,618 RAC: 0 |
Hey now! doing my best ;) A real actual astrophysicist with a knack for explaining things would be better but I don't have any. |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
cov_route Send message Joined: 13 Sep 12 Posts: 342 Credit: 10,270,618 RAC: 0 |
The results of the Drake equation always make me say..So where is everybody? |
Julie Send message Joined: 28 Oct 09 Posts: 34060 Credit: 18,883,157 RAC: 18 |
|
rob smith Send message Joined: 7 Mar 03 Posts: 22405 Credit: 416,307,556 RAC: 380 |
Spacial volume... Think of trying to find a particular grain of sand in the midst of a fully stacked hay barn.... Bob Smith Member of Seti PIPPS (Pluto is a Planet Protest Society) Somewhere in the (un)known Universe? |
cov_route Send message Joined: 13 Sep 12 Posts: 342 Credit: 10,270,618 RAC: 0 |
Think of trying to find a particular grain of sand in the midst of a fully stacked hay barn.... I would think they would try to find us or already have. These million-year-old civilizations with who-knows-what technology could have been monitoring Earth for the emergence of technological civilization and already know we're here. It's not hard to imagine an advanced civilization could have a radio or optical telescope array the size of a solar system. They could read our license plates from light-years away. Something's just not right. Maybe they're all just mean. |
ML1 Send message Joined: 25 Nov 01 Posts: 20859 Credit: 7,508,002 RAC: 20 |
Think of trying to find a particular grain of sand in the midst of a fully stacked hay barn.... You could hope for more than one civilization sending out a probe to hang out at the galactic central black hole... Your probe could wait it out nearby until the black hole evaporates, meanwhile the rest of the galaxy will have raced ahead in a much faster time frame. Then see if any other probes have come to join the party at the end of the universe... Only problem with that is... The ride back on Hot Black's ship is a little disconcerting... ;-) (HHGTTG reference... :-) ) Or at least less worse, there is no way to report back to our present time... Keep searchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
©2024 University of California
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.