user2225: The Buddha knows everything in this universe via his mind alone. Can I do the same? I want to know what is inside a black hole.

user-1: You have to practice to become a Buddha in order to reach your goal and not just a silent Buddha but a fully enlightened Buddha. A fully enlightened Buddha can know everything and anything he directs his mind at, e.g. The Four Imponderables or the black hole phenomena.

user2265: Yes, through proper (read Theravadin) Buddhist practice, an intellectual person, curious of many things will unwittingly, effortlessly gain understanding of many things about himself and the universe.
He can intentionally direct his prajna wisdom to any subject and understand it completely.
This is all I will share/write because there is so much information available. You can research the rest about the different types of prajna wisdom on Bill's meditationexpert.com site and most importantly cultivate mindfulness meditation (samatha) and vipassana. (When you have a question in your mind after stabilizing your mind through meditation, the answer will come--unless you crave the answer too strongly.)

user880: Are you sure that "The Buddha knows everything in this universe via his mind alone."? And if so, where do you know from?
If you want to know what is inside a black hole I recommend a textbook on general relativity like 
"Thorne, Kip: Black holes and time warps".
A bit more speculative is 
"Susskind, Leonard; Lindesay, James: An introduction to Black Holes, Information and the String Revolution. The Holographic Universe".
Susskind gives some information about the subject in his talk "Inside black holes" https://www.youtube.com/watch?v=yMRYZMv0jRE
Since the classical solutions of Einstein's field equations by Schwarzschild, Kerr and Kruskal we know a lot about the geometry of spacetime inside black holes. But the current conjectures about Bekenstein-Hawking entropy seem to me still a field of active research. 
Nevertheless I assume that you want to know "everything" about black holes. Physics cannot fulfill this desire. But in my opinion, nobody can.   

user625: I do not recall any teaching where the Buddha is said to know what is inside a black hole. In fact Buddha specifically states not to spend time with contemplating the heavens. The Buddha focused his attention on the present moment, which rarely includes black holes.

We go beyond outward appearances or signs and come to "signlessness."At first, we think that the members of our family are separate from one another, but afterwards we see that they contain each other. You are the way you are because I am the way I am. We see the intimate connection between people,and we go beyond signs. We used to think that the universe contains millions of separate entities. Now we understand "the nonexistence of signs."
  -Thich Nhat Hanh, The Heart of the Buddha's Teaching

The Buddha knows everything in the universe because he understands interbeing. He undersands that everything is interdependent on each other thing. There is no separate independent black hole in the center of the galaxy that is separate then the keyboard I am using to type this response. The Buddha can look at this keyboard in front of me and see the trees, the sun, the people who designed and created this keyboard, the black hole in the center of the galaxy holding us all together, and even you and me.

The Buddha said, "Dear friends, I have seen deeply that nothing can be by itself
  alone, that everything has to inter-be with everything else. I have seen that all beings are endowed with the nature of awakening."
  -Thich Nhat Hanh, The Heart of the Buddha's Teaching


user289: The Therevada stand has been covered. The details of a black hole are metaphyiscal speculations, which in general discouraged, or at least set aside as irrelevant to the Buddhist path.
In Mahayana, in the 10 grounds of the Bodhisattva path, the first seven grounds mostly are paramitas, the 8 fold path, but the last three stages you become essentially a celestial Buddha with the same powers and abilities of pretty much any mythical god-- including omniscience. ref: http://en.wikipedia.org/wiki/Ten_Stages_Sutra
Now what one would wants to do with this Sutra is a different story-- on one hand, you can look at it as being literally true and spoken by a meditation master who saw this while meditating and therefore it has to be true. 
(now entering my personal opinions) Or you can look at it some otherway-- I suspect the real point of the possibility of becoming a celestial Buddha was to emphasize how valuable & worthy it is to be enlightened, a way of encouraging Bodhichitta (the motivation to strive on the Buddhist path) in the readers.
Elsewhere in the Avatamsaka, readers are encouraged to study all sorts of topics including mathematics-- so astrophysics would be on the list-- although the value of academics in Mahayana Buddhism appears to be its value in being of use to others, less so the intrinsic value of just knowing a lot. 

user295: Buddhist meditation is about understanding misery and the way out of misery. Main aim is to get understanding of this process 4 Noble Truth.
You will get other insights in the process. I am not sure about whether you will get insights on what you are seeking. But this is a by product than a goal of Buddhist meditation.

user2143: Please consider having a better look at MN 63. Here's an excerpt which might be relevant for you:

It's just as if a man were wounded with an arrow thickly smeared with poison. His friends & companions, kinsmen & relatives would provide him with a surgeon, and the man would say, 'I won't have this arrow removed until I know whether the man who wounded me was a noble warrior, a brahman, a merchant, or a worker.' He would say, 'I won't have this arrow removed until I know the given name & clan name of the man who wounded me... until I know whether he was tall, medium, or short... until I know whether he was dark, ruddy-brown, or golden-colored... until I know his home village, town, or city... until I know whether the bow with which I was wounded was a long bow or a crossbow... until I know whether the bowstring with which I was wounded was fiber, bamboo threads, sinew, hemp, or bark... until I know whether the shaft with which I was wounded was wild or cultivated... until I know whether the feathers of the shaft with which I was wounded were those of a vulture, a stork, a hawk, a peacock, or another bird... until I know whether the shaft with which I was wounded was bound with the sinew of an ox, a water buffalo, a langur, or a monkey.' He would say, 'I won't have this arrow removed until I know whether the shaft with which I was wounded was that of a common arrow, a curved arrow, a barbed, a calf-toothed, or an oleander arrow.' The man would die and those things would still remain unknown to him.


2225: <p>The Buddha knows everything in this universe via his mind alone. Can I do the same? I want to know what is inside a black hole.</p>
 -1: <p>You have to practice to become a Buddha in order to reach your goal and not just a silent Buddha but a fully enlightened Buddha. A fully enlightened Buddha can know everything and anything he directs his mind at, e.g. <a href="https://en.wikipedia.org/wiki/Acinteyya#Four_imponderables" rel="nofollow">The Four Imponderables</a> or the black hole phenomena.</p>
 2265: <p>Yes, through proper (read Theravadin) Buddhist practice, an intellectual person, curious of many things will unwittingly, effortlessly gain understanding of many things about himself and the universe.</p>

<p>He can intentionally direct his prajna wisdom to any subject and understand it completely.</p>

<p>This is all I will share/write because there is so much information available. You can research the rest about the different types of prajna wisdom on Bill's meditationexpert.com site and most importantly cultivate mindfulness meditation (samatha) and vipassana. (When you have a question in your mind after stabilizing your mind through meditation, the answer will come--unless you crave the answer too strongly.)</p>
 880: <p>Are you sure that "The Buddha knows everything in this universe via his mind alone."? And if so, where do you know from?</p>

<p>If you want to know what is inside a black hole I recommend a textbook on general relativity like </p>

<p>"<strong>Thorne, Kip</strong>: Black holes and time warps".</p>

<p>A bit more speculative is </p>

<p>"<strong>Susskind, Leonard; Lindesay, James</strong>: An introduction to Black Holes, Information and the String Revolution. The Holographic Universe".</p>

<p>Susskind gives some information about the subject in his talk "Inside black holes" <a href="https://www.youtube.com/watch?v=yMRYZMv0jRE" rel="nofollow">https://www.youtube.com/watch?v=yMRYZMv0jRE</a></p>

<p>Since the classical solutions of Einstein's field equations by Schwarzschild, Kerr and Kruskal we know a lot about the geometry of spacetime inside black holes. But the current conjectures about Bekenstein-Hawking entropy seem to me still a field of active research. </p>

<p>Nevertheless I assume that you want to know "everything" about black holes. Physics cannot fulfill this desire. But in my opinion, nobody can.   </p>
 625: <p>I do not recall any teaching where the Buddha is said to know what is inside a black hole. In fact Buddha specifically states not to spend time with contemplating the heavens. The Buddha focused his attention on the present moment, which rarely includes black holes.</p>

<blockquote>
  <p>We go beyond outward appearances or signs and come to "signlessness."At first, we think that the members of our family are separate from one another, but afterwards we see that they contain each other. You are the way you are because I am the way I am. We see the intimate connection between people,and we go beyond signs. We used to think that the universe contains millions of separate entities. Now we understand "the nonexistence of signs."
  -Thich Nhat Hanh, The Heart of the Buddha's Teaching</p>
</blockquote>

<p>The Buddha knows everything in the universe because he understands interbeing. He undersands that everything is interdependent on each other thing. There is no separate independent black hole in the center of the galaxy that is separate then the keyboard I am using to type this response. The Buddha can look at this keyboard in front of me and see the trees, the sun, the people who designed and created this keyboard, the black hole in the center of the galaxy holding us all together, and even you and me.</p>

<blockquote>
  <p>The Buddha said, "Dear friends, I have seen deeply that nothing can be by itself
  alone, that everything has to inter-be with everything else. I have seen that all beings are endowed with the nature of awakening."
  -Thich Nhat Hanh, The Heart of the Buddha's Teaching</p>
</blockquote>
 289: <p>The Therevada stand has been covered. The details of a black hole are metaphyiscal speculations, which in general discouraged, or at least set aside as irrelevant to the Buddhist path.</p>

<p>In Mahayana, in the 10 grounds of the Bodhisattva path, the first seven grounds mostly are paramitas, the 8 fold path, but the last three stages you become essentially a celestial Buddha with the same powers and abilities of pretty much any mythical god-- including omniscience. ref: <a href="http://en.wikipedia.org/wiki/Ten_Stages_Sutra">http://en.wikipedia.org/wiki/Ten_Stages_Sutra</a></p>

<p>Now what one would wants to do with this Sutra is a different story-- on one hand, you can look at it as being literally true and spoken by a meditation master who saw this while meditating and therefore it has to be true. </p>

<p>(now entering my personal opinions) Or you can look at it some otherway-- I suspect the real point of the possibility of becoming a celestial Buddha was to emphasize how valuable &amp; worthy it is to be enlightened, a way of encouraging Bodhichitta (the motivation to strive on the Buddhist path) in the readers.</p>

<p>Elsewhere in the Avatamsaka, readers are encouraged to study all sorts of topics including mathematics-- so astrophysics would be on the list-- although the value of academics in Mahayana Buddhism appears to be its value in being of use to others, less so the intrinsic value of just knowing a lot. </p>
 295: <p>Buddhist meditation is about understanding misery and the way out of misery. Main aim is to get understanding of this process <a href="http://en.wikipedia.org/wiki/Four_Noble_Truths">4 Noble Truth</a>.</p>

<p>You will get other insights in the process. I am not sure about whether you will get insights on what you are seeking. But this is a by product than a goal of Buddhist meditation.</p>
 2143: <p>Please consider having a better look at MN 63. Here's an excerpt which might be relevant for you:</p>

<blockquote>
  <p>It's just as if a man were wounded with an arrow thickly smeared with poison. His friends &amp; companions, kinsmen &amp; relatives would provide him with a surgeon, and the man would say, 'I won't have this arrow removed until I know whether the man who wounded me was a noble warrior, a brahman, a merchant, or a worker.' He would say, 'I won't have this arrow removed until I know the given name &amp; clan name of the man who wounded me... until I know whether he was tall, medium, or short... until I know whether he was dark, ruddy-brown, or golden-colored... until I know his home village, town, or city... until I know whether the bow with which I was wounded was a long bow or a crossbow... until I know whether the bowstring with which I was wounded was fiber, bamboo threads, sinew, hemp, or bark... until I know whether the shaft with which I was wounded was wild or cultivated... until I know whether the feathers of the shaft with which I was wounded were those of a vulture, a stork, a hawk, a peacock, or another bird... until I know whether the shaft with which I was wounded was bound with the sinew of an ox, a water buffalo, a langur, or a monkey.' He would say, 'I won't have this arrow removed until I know whether the shaft with which I was wounded was that of a common arrow, a curved arrow, a barbed, a calf-toothed, or an oleander arrow.' The man would die and those things would still remain unknown to him.</p>
</blockquote>
