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  • Does radium glow in a vacuum?

    Does it cause surrounding air to glow, or does its nucleus energize radium own electrons?

    2 AnswersEarth Sciences & Geology10 years ago
  • Is it true that astrologers have predicted aliens from Nibiru will land in Area 51 in 2012?

    and provide evidence the Apollo Program was a hoax before they destroy Earth?

    C'mon, people. If you can't ask sane questions connected to reality, keep them to yourselves. The nonsense on display here every day is depressing.

    10 AnswersAstronomy & Space10 years ago
  • Global Warming science?

    The scientific method requires that hypotheses make falsifiable predictions. Since so many claim that man made global warming is "settled science" (the debate is over?):

    1. What successful predictions has it made linking climate effects directly to man made causes?

    2. What observation(s) could falsify it?

    3. How can any science be "settled" given the possibility of future contradictory observations?

    (Isn't Relativity still being tested?)

    4. Is it considered a fact, a theory or a hypothesis?

    10 AnswersGlobal Warming1 decade ago
  • Where does the energy go?

    When sound energy is canceled by noise reducing headphones, both the energy of the original sound wave and the energy going into creating the interfering wave seems to disappear. Where does that energy go?

    1 AnswerPhysics1 decade ago
  • Theory of Everything - what defines "success"?

    If a Theory of Everything (T.O.E) is eventually developed that successfully unites all forces, combines relativity and quantum physics, and makes verifiable, accurate predictions but doesn't explain what's behind quantum weirdness or the dual nature of light, will it still be considered the end of theoretical physics?

    3 AnswersPhysics1 decade ago
  • What mechanism turns elliptical orbits into circular ones?

    If a satellite is tidally locked like our Moon to keep one face always toward its planet, but has an elliptical orbit, its orbital speed is changing but its rotation rate is not. This difference would lead to some internal tidal heating of the satellite as the two motions aren't synchronized. That heating energy can't go on forever, but would lessen with a more circular, constant speed, orbit. Please explain the mechanism that changes the satellite's orbit shape to a more circular one over time to avoid the creation of perpetual heating energy.

    4 AnswersAstronomy & Space1 decade ago
  • Falling into a black hole. Where am I wrong?

    All matter in a black hole is said to fall down to the singularity at its center. Please tell me at which step I've made a mistake, and why:

    I begin far from a black hole's event horizon, falling toward it. Assume it's an isolated, supermassive one, so tidal forces and radiation aren't a problem.

    1. At first, time passing on my clock is similar to clocks further away.

    2. As I get closer to the event horizon, I notice more distant clocks are moving faster than mine. Outside observers would notice my clock moving more slowly than theirs.

    3. As I get closer, distant clocks speeds up even more as I see them. Also, light from the rest of the Universe appears to come from a shrinking disk directly opposite the black hole's singularity, and becomes more blue shifted.

    4. Very close to the event horizon, a few seconds on my clock represents hundreds of years outside the hole's influence. All blue shifted light comes from a point opposite the event horizon.

    5. By the time I reach the event horizon, an infinite amount of time has passed for the outside universe. All the other black holes in the Universe have evaporated, including mine.

    6. Therefore, I can never fall THROUGH the event horizon.

    7. Nothing else has time to fall through the event horizon for the same reason, so all its mass is located in a shell at the event's a frozen star until it evaporates.

    10 AnswersAstronomy & Space1 decade ago
  • Where does the energy come from?

    If a small moon follows and elliptical orbit around a massive planet, tidal forces will stretch and shrink it as it gets alternately closer and farther from the planet. That process generates heat, so must be using up energy. What is the energy source that is winding down?

    I can only figure that the orbit will gradually become more circular over time, generating less and less heat, but why?

    9 AnswersAstronomy & Space1 decade ago
  • Did we really go to the moon? Are there aliens? What about 2012?

    Aren't schools teaching anything besides political correctness and sex education these days?

    15 AnswersAstronomy & Space1 decade ago
  • Can you fall into a supermassive black hole? (no tidal force issue)?

    You are orbiting a supermassive black hole. Time slows (as viewed by an outside observer) the closer you orbit above the hole's event horizon, even though your clock appears to to proceed normally in your reference frame. But the time dilation is real, and you would observe clocks further away from the hole ticking faster.

    The closer to the event horizon you come, the faster outside time runs compared to your reference frame. AT the event horizon, outside time appears to move infinitely fast and the Universe ages trillions of years, while your clock would seem to be stopped to an outside observer.

    If all the above is true, the black hole will evaporate in Hawking radiation before you can cross the event horizon. How can anything fall in?

    4 AnswersPhysics1 decade ago
  • Time stops at the black hole event horizon, so how can the hole form?

    Here's an excerpt from 2007 Science Magazine:

    "Physicist Lawrence Krauss and Case Western Reserve colleagues think they have found the answer to the paradox. In a paper accepted for publication in Physical Review D, they have constructed a lengthy mathematical formula that shows, in effect, black holes can't form at all."

    "If black holes radiate away their mass over time, as Hawking showed, then they should evaporate before they even form, Krauss says."

    Answers to my previously posted question simply said time would appear to pass normally for anyone/anything falling in, so what we see (a frozen image of the faller) isn't "real". Time dilation is real, not just a mirage; and from our perspective, the hole evaporates BEFORE anyone/anything falls in.

    Has anyone seen any followup refuting the claim in this 2007 article or a better explanation of how anything can fall into an event horizon with time stopped from our outside time reference in which the black hole evaporates in a finite time?

    6 AnswersAstronomy & Space1 decade ago
  • Can matter fall into a black hole?

    All black holes evaporate in a finite amount of time. Time passes normally for an object falling in, but time stops at the event horizon from the point of view of an outside observer. So wouldn't the hole evaporate before anything could fall in?

    8 AnswersAstronomy & Space1 decade ago
  • Can matter fall into a black hole?

    For any outside observer, all black holes evaporate in a finite amount of time. But time stops at the event horizon, so wouldn't the hole evaporate before anything could fall in?

    3 AnswersPhysics1 decade ago