Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pondering Question

  1. Jul 8, 2004 #1
    When a star dies and a supernova takes place and a black hole is formed which one is more powerful, the explosion or the implosion?
  2. jcsd
  3. Jul 14, 2004 #2
    Well, thats a good question. Lets think about when each happens. An implosion happens when the core can no longer continue fusing nuclei. While an explosion happens when a nearby star or blackhole draw in the gas from the surface of a red giant, which causes an imbalance. The higher pressure from inside cause my nuclear fusion makes it explode. So, which is more powerful?? lol
  4. Jul 14, 2004 #3
    If i had to gamble i would say the implosion. I have a lot of reasons but they're very fussy, so i dont know if im right.
  5. Jul 14, 2004 #4
    A tricky question according to 'powerful' but if your refering to moving mass my guess would be the implosion since only the outer layers of the star are lossed to space mainly from neutrino flux pressure. But it's only a pure guess on my part. Ray.
  6. Jul 15, 2004 #5
    Just my opinion:

    Yes, "power" is a tricky word. The excess mass of the supergiant star remnant makes it impervious to disruption, so you might think that means it is more powerful than the ejected atmosphere, which dissipates or hangs around outside the black hole event horizon( I'll call it "exterior"). On the other hand, the material inside the black hole event horizon (I'll call it "interior") is effectively in another universe; it is unrecoverable, so it can't transmit any energy to the outside. Yes, nearby activity outside of the black hole can produce fierce x-ray and gamma ray emissions, but they represent only a small fraction of the energy implied by the interior of the black hole. Also there are those Hawking particles acting like a slow leak, but they just augment the black hole mass (everything that happens to matter at the event horizon serves to increase the mass of the black hole). Power is a transition quantity, rate of energy change per unit time. If you see the changing rate of negative potential energy of the black hole interior as power, then you can say "yes" to the question; if you count only the positive energy changes of the black hole exterior produced by the presence of the black hole, then it isn't so certain.
  7. Jul 15, 2004 #6


    User Avatar
    Science Advisor

    Not so. If there is no accretion (matter added) then Hawking radiation creates two virtual particles, a particle and anti-particle, and one particle can escape with the other particle falling back into the BH. The energy needed to produce the escaping particle always results in a mass loss of the BH, not a mass increase. This applies to "Hawking radiation" in the original sense, as there are other ways for a BH to emit "real" particles other than Hawking radiation.

    As to the original question, it depends on the type of supernova involved. In a Type I supernova, like ArmoSkater87's first post, there is actually no significant "implosion" since the explosion is caused by carbon burning (deflagration) turning into carbon detonation causing much of the white dwarf to be incinerated to iron-peak nuclei, and the white dwarf is blown totally apart. Therefore, since the Type I supernova blows the whole thing to smithereens, there is no remaining "core" , Neutron Star or Black Hole at all.

    Only in (from) a Type II supernova (single, massive star) can a black hole be created if the mass of the core remaining after the implosion-explosion exceeds about 3.2 solar masses. As to the energy of implosion vs explosion, heck, I don't know; I'll have to look it up somewhere.... :confused:

    30 Minute Edit:
    Oh, DUH! No need to look it up yet. When a Type II Supernova happens the energy for the implosion is already there in the form of unhappy gravity. In the final stages of nuclear fusion when 56Ni is converted into 56Fe (in a few seconds) the fusion into the Ni/Fe actually requires energy instead of producing energy. So, the core collapses in a second or so and it is the infalling matter and resulting runaway fusion into numerous elements, the heavy stuff too, that releases all of the energy we see and detect. If the original post meant "powerful" as energy release, then the explosion releases more because the implosion takes energy. But, "powerful" might also mean energy required for the implosion, and on that part I'm not smart enough to "do the math"... :cry:
    Last edited: Jul 15, 2004
  8. Sep 5, 2004 #7
    Surely explosions and implosions are simply sucumming to pressure? An implosion is when the core cannot hold together, and an explosion is also an inability to hold together, so surely neither is very powerful at all? A different perspective, what do you think? but as for power = force, it has to be the explosion, it depends what you mean by power.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook