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Astrophysics from a Boobie or a black climate control.

  1. Aug 18, 2010 #1
    "The mathematics, is a unique perfect method to fool oneself"

    Albert Einstein


    You can object that in this phrase there is nothing new, practically all know that Albert Einstein was not a big fan of mathematics, evil tongues even said that the mathematical apparatus for the special theory of relativity has been developed by his first wife.

    I recollected this phrase after perusal of the book including a cycle of articles of Stephen Hawking under extreme much-promising title «The Theory of everything. An origin and destiny of the Universe», St. Petersburg: Amphora, the Amphora publishing house, 2009-148 s.

    The new book has included already published in Russian works of well-known astrophysics’, and also yet not published articles, a number of points of view which inexplicably coincided with criticism which I expressed on a number of physical and mathematical forums. During May holidays I had enough time so I decided to expand and structure the arguments a little.

    So, we will return to our problem. According to Stephen Hawking - Black holes are not too black. I will not occupy readers with retelling the history of occurrence of the formulation and an explanation of the astronomical objects named Black holes, everyone can found it in scientific and popular scientific sources and moreover, we will give due to Stephen Hawking - in third lecture of the book «Theory of all» this point in question has been opened so remarkably that in my opinion, there is no any chances even to try to improve it.

    In given article I wished to discuss, actually Stephen Hawking’s idea about presence of radiation of Black holes which with figurativeness peculiar to his describes how Black holes are not too black, in the fourth lecture of the book the Theory of all.

    In short the position of Hawking can be described so – unrotative black holes should let out particles with constant speed. Further Hawking declares that he has made calculations: full similarity of a radiation spectrum of black holes to a radiation spectrum of warmed body. I will not retell the mechanism of radiation of the black hole, offered by Hawking, as the special quantum process arising owing to quantum fluctuations. Why? Simply because I am not very good with the quantum mechanics. Also I will not challenge reliability of calculations of well-known astrophysics, especially, as he confirms, that similar calculations have been confirmed by other experts at different times. Moreover, I will not use at all any mathematical apparatus, except logic positions. It would be desirable, only to underline once again a position with which Stephen Hawking is completely agree – currently there are no experimental data of existence of radiation of black holes.

    I quote «the Black hole with the weight several times surpassing weight of our sun, should have the temperature equal only to one ten-million share of degree above absolute zero. This is much less than temperature of space background radiation filling the Universe (about 2, 7 degrees above absolute zero) so such black holes should radiate less energy, than they absorb, though it is also not enough». Better to say, it is impossible to find out radiation of a black hole, as they are colder, than space emptiness surrounding them.

    According to Hawking, it is possible to find out radiation only of primary black holes (namely black holes formed as a result of the Big Bang).

    But here is a problem, such black holes are not found out, and also there is no authentic data that they exist. Speaking easier, Hawking has proved mathematical severity of radiation about which there is not any even indirect data, without speaking about the empirical data. But Hawking asserts that the spectrum of radiation of black holes is similar to a radiation spectrum of warmed body. In other words, Hawking makes the elementary thermodynamic analysis of such astronomical objects as black holes, isn't that so ingeniously? You can ask why it surprises me.

    I am not the biggest expert in the field of the thermodynamic analysis, but even I know about a considerable quantity of errors connected with the thermodynamic analysis, all data on input and output which exit is easily fixed, and here Hawking with confidence asserts that knows a spectrum of radiation of black holes about which it is experimentally known, only that they in general radiate nothing.

    It is necessary to recollect that the concept of quantum has appeared as a result of attempt of an explanation of a divergence between experimental data and theoretical estimations of a spectrum of absolutely black body radiation.

    There is an impression that the calculations of Hawking shows progress in the theoretical physics, in the beginning of 20 century physics theorists could not calculate a spectrum of radiation of ordinary terrestrial object, and now they calculate the spectrum of radiation of black holes which are so far and about which radiation there are no experimental data.

    Nevertheless, in my opinion, there is much more simple way to estimate a reality of the radiation assumed by Hawking, without use of a difficult mathematical apparatus.

    The phenomenon of black holes is known first of all for that these astronomical objects absorb any matter and even radiation. Gravitation in black holes is so strong, what even light cannot break to horizon of events (border of a black hole). Hawking for working out of his model has assumed that the temperature of a black hole is proportional to its superficial gravitation, thus, the less black hole is, the more its temperature is. Hawking considers that black holes observed by astronomers are so great that their temperature is below temperature of space vacuum that is why they absorb radiations more, than let out. Quite logical position also corresponds to usual representation about heat exchange, but we will look at it on the other hand.

    Proceeding from model of Hawking in case if black hole absorbs radiation, its weight and accordingly its temperature decreases, does not this confuse you? You imagine, you put a warm hen (warmed body) in a microwave, and the hen there freezes, then you get it out and hen warms up – the good analogy was found by Hawking, isn't it?

    Hawking declares in books that according to his calculations the spectrum of radiation of a black hole is similar to radiation of a warmed black body, but radiation is process of a transmission of energy and if we will consider this process separately from possible exothermal and endothermic reactions occurring in a black body in case of radiation the temperature of a black body should decrease. For example, our sun radiates, but the temperature on its surface essentially does not change, all business is in exothermal reactions of thermonuclear synthesis occurring in the sun, thermonuclear reactions are that source of heat which warms up a surface of star.

    Hawking has another situation, exothermal reaction in result of which black hole should radiate, as I understand, is radiation.

    According to Hawking, losing quantum of energy a black hole heats up, and absorbing the energy quantum becomes colder. But first of all radiation is a process of energy transmission, a thermal stream always (disregarding likelihood deviations) is directed from hotter body to less, itself heat transfer does not lead to a warming up of a body losing heat, thus, any analogy to radiation process of warmed body, with process of radiation of a black hole cannot have, as the process described by Hawking, it actually not only process of a transmission of energy, but also not described by him exoteric reaction and such process cannot be similar to radiation of warmed body (Hawking radiation actually is not a radiation).

    According to Hawking, the black hole is similar to the system of an ideal climate control, if we pick up a primary black hole which size is equivalent to a room temperature, it can work as the eternal conditioner, for example cooling and heating up a premise, without an energy and heat removal supply.

    In his book Stephen Hawking asserts that if scientists will find a primary black hole possibly they will receive the Nobel Prize, in addition I would like to notice that, in my opinion then the first perpetual mobile of a natural origin will be found out. Otherwise Hawking will be compelled to show these endothermic and exothermal reactions which in his model are connected with absorption and radiation of black holes.
     
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  3. Aug 19, 2010 #2

    Janus

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    It won't work that way. Since the black hole is radiating its energy out into a larger space, in order to maintain the room temp against outside losses, the surface temp of the BH has to be higher than the room temp. (for the same reason, the surface of a wood stove maintaining a temp of 70F in a room will be much warmer than 70F.)

    Thus the black hole will continue to radiate away energy at a greater and greater rate. Since the room temp of the larger space will always lag behind the temp of the BH, and the BH will continue to radiate until it exhausts its mass.
     
    Last edited: Aug 20, 2010
  4. Aug 20, 2010 #3

    Chronos

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    Theoretically a solar, or more massive black hole mass will survive for dang near forever - long enough for the cmb and all other background radiation to diminish to virtually zero. So, I fail to see the issue.
     
  5. Aug 28, 2010 #4
    I did not speak about larger space , I told , about room which mass should be much less than mass of BH.
    In that case, speed of increasing temp. room will be much higher than speed of increasing temp. BH.
     
  6. Aug 28, 2010 #5

    Chronos

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  7. Aug 28, 2010 #6

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    Start with a room at room temp with a BH at room temp. The room loses some heat to the outside environment, and the room's air temp drops with respect to the BH temp. The BH energy release goes up. This energy has to be spread out to the surrounding air. The air has absorbed some of the energy of the BH, so while the air temp goes up, the average temperature of the room + BH will still be less than the temp of the BH itself. The heat is distributed between BH and air and since the mass of BH and air is greater than that of the BH itself, the average temp goes down. This results in the room air always being at a lower temp than the BH. The BH will heat up, heating the air more, but as long as the room is still losing heat to the outside environment, its temp will lag behind that of the BH.


    The only way the system would maintain a stable temperature is if the room was perfectly insulated from losses to or gains from the outside. Then the room and BH would sit perfectly at the same temp forever. However, the same stable temp would be maintained in such a perfectly insulated room without the BH, so the BH adds nothing towards maintaining room temp.
     
  8. Aug 29, 2010 #7
    What you told, is absoultelly correct for a normal warmer body but,
    BH according Hawking is different at least for two points :
    1-temp of BH is reverse proportional to the whole BH mass
    2-BH absorbing energy (radiation) getting cooler (not warmer, like normal body).

    Based on that, the temp of the room air is not always lower than temp of the BH.
    Let's pretend that BH transfer one quantum of energy to the room.
    As mass of BH is much higer than the mass of the room, so the temp of the room just for the moment becomes higer than temp of BH and this should result to opposite direction of heat transfer also the for very small moment of time.
    According Hawking BH absorbing energy (radiation) is getting cooler (not warmer, like for normal body).
    Opposite direction of heat transfer , will result to decreasing temp of BH (but not increasing like normal warmer body), so temp BH wiil be stabilised.
     
    Last edited: Aug 29, 2010
  9. Aug 30, 2010 #8

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    Wrong. The mass of the Black hole vs the mass of the room air has nothing to do with how much the BH will heat the air. That's a red-herring. What counts is the temp of the surface boundary and its area.
    Thus a black hole radiating at room temp may be 4e20 kg in mass, but due to its extremely small surface area will only radiate at a rate of 2.56e-43 watts. A rate of 2.56e-43 watts isn't going to heat the air in the room at anywhere near the rate that the air loses heat to the outside environment.

    Even if you only surround the BH by a thin shell of air, the inside surface area of that shell will be smaller than the outside surface. The larger outside surface will be better at radiating away heat to the external environment than the inside will be at absorbing it from the BH. And since the inside of the shell has to be outside of the event horizon, its surface area will be larger than the emitting surface of the BH, and will be at a slightly less temp than the BH to begin with.

    For the air shell to be in thermal equilibrium (emitting at the same rate as it absorbs), the outside of the shell must be at a lower temp than the inside. Thus the average air temp will be less than that of the BH.

    No, it won't, for the reasons above. The room, in order to maintain thermal equilibrium and due to its much larger external surface area, will have to have a temp lower than that of the BH. The BH will continue to radiate, getting hotter as it loses mass, but as the room heats in response, its rate of loss to the external environment increases also, always maintaining a lower average temp than the BH.
     
  10. Aug 31, 2010 #9
    In my opinion Red-herring is as well:
    when you comparing 4e20 kg in mass and 2.56e-43 watts.
    when you comparing outside surface and inside surface boundary conditions

    In general, I agree that in certain boundary conditions Hawking BH could work as heating, for example, during cold nights but
    let's pretend during hot days the temp outside room becomes much more than temp of BH, and as result temp of the air in room becomes more than temp. BH. According Hawking, BH should start working as conditioning.

    If we choose proper isolation the for room , Hawking BH will be working as good perpetual mobile, heating room during nights and coooling during days.

    I am waiting Nobel prize !!!!!
     
  11. Sep 5, 2010 #10

    Chronos

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    The commitee will be in touch as soon as the first galactic core black hole evaporates.
     
  12. Sep 10, 2010 #11
    I see no one, even now.
     
  13. Sep 10, 2010 #12
    cough cough spit ugh
     
  14. Sep 22, 2010 #13
    As soon as I see no further support of Hawking radiation.
    I propose to discuss Opposite Thermodynamic Arrows of Time in BH authors of which is me, Hollywood, and L. S. Schulman, and what is, in my opinion, the better alternative model of thermodynamic BH comparing to perpetual mobile of Hawking radiation.
     
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