Spyman

J.C.MacSwell is just joking on the topic "How to cancel out earth gravity". There is no such thing or machine which is able to do that. It is still possible to fly or have stuff levitating, with airplanes or like with this machine. But it doesn't work by stopping gravity.

Link to Wikipedia: http://en.wikipedia.org/wiki/Black_hole Also Google is a good search engine You can use.

Sorry, I thought it was for Johnny5, (since You adressed him in that post). "Einstein will be happy to know that you give him unlikely plausibility..." He removed the cosmological constant himself, (with relief I heard). "of which... you have yet to produce any of." I woun't either, I will be satisfied if I am able to understand only small parts of my interests. "Do the math." I am not so good in advanced math. "I have no clue what you're talking about." It should have been it instead of i, which I have corrected now. What I meant was that I can't understand how the mass-energy and vacuum energy nearly can balance at different distances and different mass. "yes, the only valid perpetual motion machine" This is really a problem for me, even after reading Your link. With "in a very complicated way that seems impossible for me...", I don't mean that You are wrong or that I am trying to prove otherwise. I simply means that I can't fully understand You and some of the parts I can sounds impossible to me. BTW I have a math question here: http://www.scienceforums.net/forums/showthread.php?p=147778#post147778 Maybe You can help me out, since Martin may have forgotten it ?

island, You have explained the "grip", but in a very complicated way that seems impossible for me... Possible but unlikely. Makes Your view cind of incomplete... I can't understand how it can nearly balance with both different bodies and at different distances.The distance for balance must be different if the mass of the bodies is different and the unbalance must increase when the distance grows. Perpetuum mobile ? Not only will it keep on going, it will also amplify itself and produce matter ?

I would really appreciate it ! I am talking about a Hawkings view of a Newtonian Universe, NOT A PLANET. Correct ! Let's start with explaining why it would collapse in the first place, should we... Actually BlackHole managed to give me some inspiration with his post: I tried to solve this by simply growing a 1D Universe and got stuck with Newton's idea. But if I insted take a 3D spherical Universe, like a planet with a density, then the gravity at the distance X from the center will stay constant when the sphere grows, if the density remains the same, thus Hawking's are correct.

Yes, but Hawking implies that even if their view is very alike our and someone at their horizon also has a view alike ours and so on to infinity, if matter is infinite and evently distributed in an infinite space - it still would collapse to one single body. I want to know why Hawking assumes this because I am stuck in the "mindtrap" he claims Newton was in.

I don't know what "invariant mass" is either, hopefully that swansont will explain...

As I said in YT's thread it's Newtons second law, it does'n include relativity. According to relativity the force must change to be able to hold a constant acceleration. The relativistic mass is determined by the objects rest mass and velocity. Thus its mass will not change when it approaches light speed, it will change as soon as the velocity changes and then grow larger to reach infinite at c. With relativity, "in a normal situation", two identical objects under the same constant acceleration will have to be under two different changing forces, if one object has accelerated for 2 seconds and the other accelerated for 4 seconds. But "in a normal situation" the difference between relativity and Newton is so small that it is more practically to use the Newtonian way. So when the velocity gets high, somewhere at half the speed of light, I think, the difference is large enough to make relativistic calculations worth the effort. Why the world is created in such a manner nobody can tell You, it's just the way it is.

Newtons second law is "Force = Mass x Acceleration". Acceleration is at which rate a body changes Velocity caused by the Force. For example in an impact the bodys don't change velocity at instant, they accelerate. (but sometimes very fast) The new velocity is thus depending how long time the force acts on the body.

Yesterday I read a book, in my language, called "COSMOS a short history" with the original title "A brief history of time" by Stephen W. Hawking 1988. The book is mostly a history of the progress of science, with parts of self-biography and some cosmological ideas of him for the general puplic. I got stuck already on page 17 where Hawking implies there is a center of mass of the Universe. (At least in a infinite Newtonian Steady State Universe.) I don't intend to discuss if the Universe has a center of mass or not, just what Hawking implies or not. What I want to know if this prof, (math ?), exists or if Hawking is just over-simplifying in a way such it favours his idea of a masscenter ? (If it exists, how it works and if it is commonly accepted or not ?) If someone has the book in English it would be nice to have this quoted so I could read that part with Hawkning's own words. I will here try to translate the part back to English: "If the numbers of stars was infinite and they where more or less evently distributed in an infinite space, wouldn't the universe collaps since the stars shouldn't have any center to be pulled against, according to Newton. This way of thinking is an example of errors of the mind when dealing with the infinite. The correct way to deal with this cind of problem - which people realized later - is to start with a finite solution and interpret how the situation changes when adding on more and more evently distributed stars outside this area. We can add how many stars we want and they will still collapse to one single body." For me it somehow sounds backwards to prove the Universe has a center of mass starting with the assumption that the Universe has a center of mass. On the other hand it's not likely for someone like Hawking to go puplic with such a huge general/basic flaw.

Johnny5, please keep Your discussion about "how photons mediate the gravitational force" in Your thread. Found here: http://www.scienceforums.net/forums/showthread.php?t=10428

Martin, we seem to go around in circles here...I guess You have plenty of things going on and can't remember where the discussion was when You left off. (You have recommended the article, I have read it, it didn't supply me with an answer.) What I need is a straight forward answer, if I interpreted Your view correct or not ?

Thanks for all the links ! I will try to read through them when I get the time needed. BTW Are You trying to convince me or Yourself ? Just out of curiosity one might wonder since You have not presented a consitent view of Your own. You seem to favour any idea that is against an expanding space-time. Or are You just polite and giving a lot of links for me to decide on my own ?

Do You know how to use a compass ?

I started my post with "I think" which means I am not going to try to justify it = It's just my thoughts.

I meant the odds of having Earth as the only place in the hole Universe with the correct circumstanses for life to arise must have lower odds than having at least one more place and the Earth. BTW: Half Your post is inside the qoute of my post.

I think life will arise everywhere there is a possibility, not just by chance. To have the Earth as the only place in the hole Universe with the correct circumstanses for life to arise must have lower odds than the opposite.

Yes, I just wanted to point out the difference.

Isn't that the odds of picking out the balls in random order ? I thought YT2095 wanted the odds of picking them in the order of 1,2,3,4. Which should be (1/40)*(1/39)*(1/38)*(1/37) = 1/2 193 360 Almost impossible odds.

Martin and island, communication between different people with different science knowledge, using advanced scientific words, in a for me foreign language, is not easy... island, I apologize again for misinterpreting Your posts. I have reread all island's posts in this thread and I still have trouble "connecting" them with Martin's view, maybe it's because Martin take a more common approach and island specific stick to Ned Wright's or I am still not able to understand island. (or misinterpret Martin also) To clearify which is which I will try to show, how I perceive, the differences: island view) Vacuum energy, vacuum have gravity which pushes bodies apart, the speed due to the push is not exceeding light but the creation of new vacuum causes that, important is that the push cancels out the normal grip of gravity between the bodies, energy don't have to be conserved since new energy is inserted from the vacuum. Martin view) Inertia, the metric is changing and nothing moves, energy is conserved by also streaching gravity together with space, the gravitational energy between the objects being streached apart is constant, so gravity is sort of "amplified" relative the metric with the same rate as expansion. So am I right or wrong ? Both views explains the missing "grip" but are not exactly the same.