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Space Science

Milky Way's Black Hole a Gamma Source? 100

Posted by kdawson
from the high-energy-pinball dept.
eldavojohn writes "A paper recently accepted for publication (preprint here) proposes a sound explanation for the source of the gamma rays that permeate our galaxy. The Milky Way's central object Sagittarius A*, widely believed to be a supermassive black hole, is now suspected to be the source. To test this theory, two scientists created a computer model to track the protons, flung outward with energies up to 100 TeV by the intense magnetic fields near the event horizon, as they make a random walk through the plasma environment. It can take thousands of years for them to travel 10 light-years from the black hole, where they collide with lower-energy protons to form pions. These decay into gamma radiation emanating from a torus-shaped region around the central object."
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Milky Way's Black Hole a Gamma Source?

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  • Re:Do we know? (Score:5, Insightful)

    by MightyMartian (840721) on Tuesday March 06, 2007 @05:20PM (#18254984) Journal

    I've been semi-interested in Cosmology/Astrophysics lately, and from everything I've seen and read so far, I've ascertained that we don't know much. Between dark matter, dark energy, gravity, black holes, big bang, etc. it seems like we just conveniently make up "stuff" to fit some model or equation. Do discoveries like this mean anything at this time considering there's no way to prove any of it?
    Translation: I know the names of some scientific fields, but never read more than the science headlines in the newspaper. Clearly this is the fault of scientists.
  • Same here (Score:3, Insightful)

    by quokkapox (847798) <quokkapox@gmail.com> on Tuesday March 06, 2007 @05:42PM (#18255252)

    I've been semi-interested in Computer Science/Mathematics lately, and from everything I've seen and read so far, I've ascertained that we don't know much. Between dark fiber, optimal algorithms, P=NP, O(n log n) (and other equations like that), cryptography, etc. it seems like we just conveniently make up "stuff" to fit some model or equation. Do discoveries like this mean anything at this time considering there's no way to prove any of it?

    [No offense intended--just pointing out that a lack of sophisticated understanding in a field of study does not imply the field is in any way bogus or the knowledge is "shaky". The reason it's called "dark matter" or "dark energy" is precisely because we aren't sure exactly what it is yet.]

  • Re:Do we know? (Score:4, Insightful)

    by Ibag (101144) on Tuesday March 06, 2007 @06:28PM (#18255776)
    While this probably is an accurate translation, GP has a point. A lot of science can seem rather ad hoc at times. Before we had discovered all the planets, scientists noted that the orbits of the known planets were not quite what they should be. Instead of declare that newton's theory of gravity was wrong, they theorized that there was an unknown planet. After doing some calculations, they determined where this planet had to be, looked up at the sky, and found Neptune.

    Similarly, when cosmologists look at the apparent rate of expansion of the universe (and how that rate has changed over time), they get that if their model of the way things work (general relativity) is correct, then their estimates of the mass in the universe based on empirical observation cannot possibly be right. Instead of abandoning relativity and leaving a void in its place, they say, "This will work of there is a large amount of matter that we can't observe. Dark matter!" Of course, this doesn't resolve everything, and we need various other adjustments (like dark energy, or physical constants that aren't constant) which look like kludges, but which have predictive power and are the best answers we've got.

    Do we "know" this is correct? Of course not! We don't even know that the next time we drop an apple, it will fall to the floor. Science is a process, though, and it isn't productive to dismiss the theories of today before we've seen the observations of tomorrow.
  • Re:Do we know? (Score:5, Insightful)

    by ChrisA90278 (905188) on Tuesday March 06, 2007 @07:27PM (#18256524)
    "Do discoveries like this mean anything at this time considering there's no way to prove any of it?"

    There is no way in science to PROVE ANYTHING. All one can do is disprove a theory you can never prove a theory to be true. This is a very basic part of how science works

    A theory is a good theory if it is predictive and makes good predictions and it is disprovable and it has not been disproved. But a theory can't be proven to be true.

    Have you ever read Wittgenstein? Goggle the name. He wrote, long before the 1960's a question "Have I ever been to the moon?" He argued that while he thought he'd never been there and knew of no one who had he could not prove he's never been to the moon and further that such proof was impossible. Proof is very different from being very, very certain. He goes on to explain the difference and what can and can not be proven. Some things can never be proven not matter what you do

    In science all you can be is "very certain" but must always be open to being proven wrong. For example we think and are very certain that light follows the inverse square law but can you prove that it ALWAYS does? It only takes one exception to disprove the theory but a trillion observations would not prove it true.
  • Re:Do we know? (Score:3, Insightful)

    by Ibag (101144) on Tuesday March 06, 2007 @09:58PM (#18257822)
    Well, I think that there is an important way in which this is nothing like epicycles. With the theory of epicycles, people (I hesitate to call them scientists) were looking to describe how the heavens moved without much thought of why. Here, scientists are working with a theory of why the world behaves as it does, and is trying to tweak parameters to make the model obey observation. When people added circles within circles to make the epicycles more accurate, there was no reasonable explanation for why this should be the case. Now, we have a reasonable sounding explanation that "the physics of over there should be the same as the physics over here." This is science. That was not.

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