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Thread: The Official Cricketweb Science Thread!

  1. #31
    Hall of Fame Member luckyeddie's Avatar
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    Yaju : no, I agree that the ill-treatment of women is not funny, and I don't have an answer.

    As far as the other questions you pose, they are rhetorical. This doesn't mean that they do not have an answer - you just have to look inside yourself for the solution.

    Nigel Clough's Black and White Army, beating Forest away with 10 men

  2. #32
    Hall of Fame Member luckyeddie's Avatar
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    The 'Schrodinger's Cat Experiment' is not a puzzle but a paradox. It was Schrodinger's attempt to say 'There are more things in Heaven and Earth, Horatio, than are dreamed of in your philosophy'.

    What he was getting at was that quantum mechanics by definition is confusing, and can never be an exact science (see my earlier reference to Heisenberg's Uncertainty Principle), because everything is expressed in the form of probabilities.

    As for the cat, he has been in the box with the beta emitter and the acid for 75 years now. Assuming that the cat could live for ever without being doused in acid and didn't need any food, it is still possible that he is still alive. After all, even with a 50% chance of discharge within one hour, 75% chance within two and the like, we STILL haven't reached 100% and never will.

    I know that this has not answered your question. I had no intention of doing so when I was an 18-year-old knowitall. 31 years later (and still a knowitall ) I recognise the folly of trying.

  3. #33
    Hall of Fame Member luckyeddie's Avatar
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    Why is a fusion reaction the safest?

    It isn't. Full stop. see my earlier references to novae, supernovae and black holes.

    What it is, as far as the environment is concerned, is the cleanest.

    As I earlier intimated (sorry to keep going back), nuclear fusion releases a tremendous amount of energy from relatively harmless substances within the process of the formation of other relatively harmless substances.

    You require fuel (hydrogen), heat and/or pressure, cos you've basically got to ram together (fuse) the nucleii of the hydrogen atoms in order to form helium. There's the small point of a couple of odd electrons buzzing about the place, so duck!

    The energy released in the process is enormous (the temperature of your friendly neighbourhood fusion reactor - the sun - is around 20,000,000 degrees at its core).

    OK, it's essentially free, so why are we not already using it? Well, there's plenty of work going on at the moment where fusion reactions are being controlled, but the experiment only lasts for about one 1,000th of a second.

    We need to learn how to contain the reaction in such a way that some of the energy is fed back into sustaining the containment field, and then to use the resultant heat to (probably) turn water into steam and turn a turbine in the usual power-stationy way.

    I reckon by the end of this century the problems will have been cracked and the world will have 'free' (ish) energy.

    It is the scientific (physics) 'Holy Grail' - and is the reason why so many people were so excited when Fleischmann and Pons announced their (sadly flawed) 'Cold Fusion' experiment results a few years ago.

    Very bad physics joke : "Is Cold Fusion here to stay, or is it just a Fleisch in the Pons?"

  4. #34
    State Vice-Captain Gotchya's Avatar
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    Is the mass infinite (like you said Eddie) in the case of a singularity, or is mass finite but very large (what I think), and because of zero diameter (zero volume), the density goes to infinity?

    Okay lets try to view it in the terms of the formation of the black Hole:

    (Karl Schwarzchild in 1916 who derived an equation for the Schwarzchild Radius of a black hole (Rs = GM / c^2, where Rs is the Schwarzchild radius, G is Newton's gravitational constant, M is the mass of the blackhole and c the speed of light).)

    To form a black hole matter collapses under its own gravitational field, such as in the death of a large star. If the matter in question is massive enough then its gravitational attraction will be so great that it will overcome all of the other forces trying to resist the collapse and the matter will continue to shrink until it becomes no more than a point, known as a singularity (Therefore it will have an Infinite Density). This point will have an infinite density and will be infinitely small.

    Continuing on the singularity/black hole topic...black hole by definiton is concentrated mass, which has formed due to no more hydrogen left on a star to keep it from collapsing onto itself, and hence nothing that comes near it can escape due to the enormous gravity. Now is there a way to find out what happens inside a black hole, and is it possible that every black hole goes on collapsing and eventually becomes a black hole?
    The Schwarzchild radius describes a property of black holes known as the event horizon. This is the point between space where light can escape from the black hole's gravitational field and the space where it cannot. Although the singularity inside the black hole is infinitely small the black hole would appear to be the size of its event horizon, and to all effects is.

    When matter falls into the event horizon it becomes isolated from the rest of space and time and has, effectively, disappeared from the universe that we exist in. Once inside the black hole the matter will be torn apart into its smallest subatomic components which will be stretched and squeezed until they to become part of the singularity and increase the radius of the black hole accordingly.(A consequence of the conservation of matter/energy)

    Interestingly enough it has now been shown by Stephen Hawking, that the matter inside a black hole is not completely isolated from the rest of the universe and that given a sufficient length of time black holes will gradually dissolve by radiating away the energy of the matter that they contain. (Ref. brief history of time)

    As far as the question of the black holes eventual evaporation, thats a tad difficult to answer.Stephen Hawking came up with theoretical arguments showing that black holes are not really entirely black: due to quantum-mechanical effects, they emit radiation. The energy that produces the radiation comes from the mass of the black hole. Consequently, the black hole gradually shrinks. It turns out that the rate of radiation increases as the mass decreases, so the black hole continues to radiate more and more intensely and to shrink more and more rapidly until it presumably vanishes entirely.

    Actually, nobody is really sure what happens at the last stages of black hole evaporation: some researchers think that a tiny, stable remnant is left behind. Our current theories simply aren't good enough to let us tell for sure one way or the other.

    What he was getting at was that quantum mechanics by definition is confusing, and can never be an exact science (see my earlier reference to Heisenberg's Uncertainty Principle), because everything is expressed in the form of probabilities.
    Couldn't agree more with u there. Quantum world is one in which particles bounce from one point to the other without traversing the in between, u can never be sure of these theories, as most of them are highly hypothetical, and cannot be easily tested.
    Once the game is over, the king and the pawn go back in the same box


  5. #35
    Cricket Web: All-Time Legend Top_Cat's Avatar
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    Also, why do they say that if there is a fusion bomb, it would not harm the buildings but only people?
    You're thinking of a neutron bomb. High speed sub-atomic particles which kill everyone within a 20-50km radius and do little damage to physical structures. An insidious device in my opinion.

    Funny? Ill-treatment of women funny?
    No, you doofus I was making the point that this thread is a science thread, not a philosophy thread (though when we're talking big bangs, maybe the two can't avoid each other).

    The big knock against fusion reactors is that the amount of energy you put in to force the fusion of nucleii to occur isn't sufficiently less than what you get out of it to make it worthwhile. Cold fusion was the beginning of the idea that we could get a fusion reaction without expending anywhere near as much energy but so far, it's still a bit of a novelty.

    Eddie already beat me to answering your questions
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  6. #36
    Hall of Fame Member luckyeddie's Avatar
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    Thanks, Gotchya.

    I realise now that I hadn't explained things as clearly as I could regarding black holes and their formation.

    The interesting aspect about them is the postulation that they can radiate energy, and consequently even the name 'black hole' is a misnomer.

    That'd be fun - you're using the old wormhole to flit from one side of the universe to the other in an instant, and one of its anchor points suddenly chooses that particular instant to disappear up its own event horizon.

    That's when you KNOW you're having a bad day!

  7. #37
    State Vice-Captain Gotchya's Avatar
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    That'd be fun - you're using the old wormhole to flit from one side of the universe to the other in an instant, and one of its anchor points suddenly chooses that particular instant to disappear up its own event horizon.
    Exactly.Its a universe with infinite possibilties!. Didn't include anything abt em bcoz could have clutered ideas. Just for the benefit of our discussion then, since the equations of relativity are symmetric in the space-time curvature, they would hold true in the opposite direction as well. Therefore with these new solutions in this direction, we'll have something called a 'WHITE HOLE'.Which is the exact opposite of a black Hole. Since you can only throw in matter in a black hole, a white hole could only spit it out!!. And if you happen to have a combination of a black hole and a white hole you 'would' have a warm hole (Holly wood stuff really). Now if you were to fall in you could hypothetically travel huge distances in a very very short time!!

    I realise now that I hadn't explained things as clearly as I could regarding black holes and their formation.
    No problem feels good to lend a hand.
    The interesting aspect about them is the postulation that they can radiate energy, and consequently even the name 'black hole' is a misnomer.
    yes. Now it can be used only to imagine a big black monster upthere somewhere that gobbles up everything that comes its way!



    [Edited on 8/8/02 by Gotchya]

  8. #38
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    Since this seems to be the thread for all the science buffs I thought you might be interested in this piece of news that came out of Australian scientists yesterday...

    Apparently, E=mc2 (squared) - Einstein's most famous formula - is wrong!! Scientists now have a theory that light is in fact not a constant... and that it actually slows down with time.

    Interesting. Any thoughts??



    And another question: why does a cricket ball reverse swing???


  9. #39
    State Vice-Captain yaju's Avatar
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    It can be wrong. Not yet.

    Scientists are to verify this.
    Yaju
    Self Proclaimed World's Greatest 12th Man.

    I like wasting homo sapiens' time - like the way I wasted yours just now.

    Quote Originally Posted by 5N1p3R j0C|<
    Why are you wasting time your reading others' quotes?
    Quote Originally Posted by DD
    <quack>

  10. #40
    Cricket Web: All-Time Legend Top_Cat's Avatar
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    Interesting. Any thoughts??
    At this stage it's far from being proven to be true but it wouldn't surprise me.

    And another question: why does a cricket ball reverse swing???
    It has to do with air resistance on a rough vs smoothe surface and the weight of one side of the ball being heavier. The way to get a ball to start swinging reverse is to weigh down one side of the ball with moisture and keep the other side rough. Works a treat.

  11. #41
    All Time Legend Paid The Umpire's Avatar
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    For those people who want to learn about star stuff... listen to STAR STUFF!

    It is on Sunday nights (9pm WST) on ABC News Radio.

    It is really good to listen to if you are a poor pathetic little human.

  12. #42
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    Who coined the term reverse swing? I think it was Imran, but it would be good to have it verified.

    I had no intention of doing so when I was an 18-year-old knowitall. 31 years later (and still a knowitall ) I recognise the folly of trying.
    LOL!

    White Hole!! Wow, Interesting, never heard of that term, but as you say theoretically due to the symmetrical nature of relativity calculations, it could exist. How would it be explained physically though? i.e. Black hole is a star collapsing onto itself due to the lack of hydrogen/fusion, can a white hole be xplained in a similar way?

    BTW, now it makes sense why on one of SH's books I read 'black holes arent black'. So, inside a balck hole time stops? hence if we can spend a year in a black hole (and somehow manage to keep from getting shredded to very small pieces), and for us it would be no time elapsed.

    Here is a dumb question, if time is relative, and if we travel really fast, time moves very slow, so what if we travel half as fast as the speed of light or maybe ten times as slow as the speed of light, would time for us still slow down i.e. slower than other people.

    I feel like a kid in a free candy shop, I can ask anything, no matter how stupid or extravagant, and I magically get the answer, fast and free

  13. #43
    Cricket Web: All-Time Legend Top_Cat's Avatar
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    Here is a dumb question, if time is relative, and if we travel really fast, time moves very slow, so what if we travel half as fast as the speed of light or maybe ten times as slow as the speed of light, would time for us still slow down i.e. slower than other people.
    What you're talking about is 'time dialation' and yes time does change relative to the speed your going and your frame of reference. The most famous thought experiment on this was the train and two crackers experiment:

    Say you have two people in this experiment, one on a hill watching a moving train go past and the other on the train itself. Now, when the train reaches a certain spot, a firecracker at either end of the train go off simultaneously. The stationary person on the hill sees both firecrackers go off at the same time in his frame of reference whilst the person on the train, depending on the speed of the train, will see a slight delay between the crackers in their frame of reference. Obviously you'd need to be going pretty damn fast to 'see' the delay but you get the idea.

  14. #44
    State Vice-Captain Gotchya's Avatar
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    Black hole is a star collapsing onto itself due to the lack of hydrogen/fusion, can a white hole be xplained in a similar way?
    Well they cant.

    White holes are a perfectly valid mathematical solution to the equations of general relativity, but that doesn't mean that they actually exist in nature. In fact, they almost certainly do not exist, since there's no way to produce one. (Producing a white hole is just as impossible as destroying a black hole, since the two processes are time-reversals of each other.).


    Dont know why but i have been feeling very generous !! :P

  15. #45
    Hall of Fame Member luckyeddie's Avatar
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    A good demonstration of time dilation effects can be found on the website of Walter Fendt :

    http://home.a-city.de/walter.fendt/p...l/timedil1.htm

    Pluto is approximately 5 light-hours from Earth. If we hop in a space ship and fly there at 99.99% of the speed of light, then to observers on the Earth, the spaceship takes a fraction over 5 hours to make the trip, but for the passengers on the spacecraft, only 5 minutes would have passed.

    Try it - it's fun!

    And if you want the mathematical expression, it's

    t1 = t((1-(V**2/C**2))**0.5)

    Where C is the speed of light, V is the velocity of the ship, t is the elapsed time for the journey as observed from Earth and t1 is the elapsed time as observed from the spaceship.

    Even at speeds approaching 20% of the speed of light, savings are extremely minimal. In order for true inter-stellar travel to become a possibility, speeds approaching 99.9% of the speed of light would be necessary (or suspended animation for the travellers).
    Trouble is, will there be anyone waiting for them when they get back?

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