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Stocks have reached what looks like a permanently high plateau. Irving Fisher, Professor of Economics, Yale University, 1929

1. MOST OF THE UNIVERSE IS MISSING Previous | Next

We can only account for 4 per cent of the cosmos

IN 1997, astronomers discovered that the universe is expanding at ever faster speeds. No one knows why this should be: until that point, everyone assumed the universe's expansion would be slowing down after the big bang. The best explanation we have – that some mysterious thing called “dark energy” is causing the accelerated expansion – is no explanation at all because we have no idea what this dark energy actually is.

We can say the same about “dark matter”. If you take our best understanding of gravity, apply it to the way galaxies spin, and you'll quickly see the problem: the galaxies should be falling apart. Galactic matter orbits around a central point because its mutual gravitational attraction creates centripetal forces. But there is not enough mass in the galaxies to produce the observed spin. The best response from physicists is to suggest there is more stuff out there than we can see, and that the gravity of this stuff is holding everything together. Just as they called the mysterious accelerating stuff dark energy, they call this mysterious gravitating stuff dark matter. We’ve been searching for dark matter for decades now, but we still have no idea what it might be.

That may be because dark energy and dark matter, which together seem to make up 96 per cent of the universe’s contents, might be a cosmic mirage. We may find out that the dark energy vanishes in a puff of logic when we rid our mathematics of certain assumptions – such as the assumption that the universe is the same in every direction. Dark matter might be a result of us not quite understanding how gravity works. The issue is still wide open.

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Location:Spokane, WA USA
Joined:20/08/2008
Posts:6

#1 - Posted: 21/08/2008 19:16

As I have pointed out in my previous post on acceleration.  Gravitational, Electric and magnetic fields are similar in that they all seem to diminish in strength with the square of the distance.  However they are different in two respects.  The stronger the field, the shorter the initial distance that is required for the force to be cut in half.  For example, a magnets force may be half as strong at a distance of  less than a centimeter; however one must get eight thousand miles from the center of the Earth before its gravitaional strenth is cut in half.  (The International Space Station does not really experience "zero gravity."  Actually gravity is almost as strong there as on the Earth; however, angular acceleration "centrifugal force" exactly compensates for gravity so that objects in orbit experience no net force.)

To summarize, we have three general field properties

1) Initial distance to cut field strength in half.

2)  The stronger the field the shorter the  half-strength distance.

3)  The familiar inverse-law of field strength diminution.

Inverse Square Field Law Modification

I propose a fourth law.  

4) The weaker the field, the longer the half-strength-distance "constant."

I think that gravity diminishes at a slower rate than the inverse law would by itself suggest.  I think the inverse law still works, but that the half-force-distance gets larger with distance from the field source.  I think this is a consequence of the second principle.

2)  The stronger the field the shorter the  half-strength distance.

The only new insight here is that principle number two might apply to the same field over great distances!

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