>Hi Hilmar,
>
>This may explain why earth seems to be gaining in velocity, rather than slowing down. Perhaps a black hole is attracting us towards its gravitation pull.

I suppose you refer to the recent news that a leap-second was not required for the last five years.

IMO, a black hole, close-by, should not change the velocity of the Earth's rotation, at least from our point of view.

The Earth is believed to rotate slower and slower, due to tidal forces. This is throughout millenia, or millions of years; in the short-term, the speed of rotation may vary in both directions.

If a ballet-dancer makes turns (rotates) on the floor, with her arms extended, and then pulls her arms in, she will start turning faster. You can try this for yourself, but watch out that you don't fall on your nose <g>.

This is due to the conservation of "rotational momentum" or something.

I am talking about angular velocity here, which is relevant for the Earth's rotation.

So, a small re-distribution of mass, for instance, ice accumulating or melting at the poles, can measurably change the Earth's rotation in the short term. There is no big mistery involved, it is just that (pressumably) the exact details, of where this mass relocation occured, is not known.

>It is though that black holes are consuming matter within the universe.

This is obvious, from the physics involved. Black holes were commonly believed to be big "monsters", that would gradually suck up all matter (and this may very well happen, but in a very long time). However, it is only recently that black holes are also recognized as having a creative role. Where there are galactic black holes, stars will form! The exact details are not yet known; it might be related to some shock-waves emitted by the black hole.

> Black holes cannot be seen, because even light is caught within a black hole's gravitation pull and compacted into its matter. Since the strength of an object's gravitation pull is related to its mass, black holes would be continually gaining in gravitation pull strength as they consumed more and more matter.

Yes, right. A black hole can be detected at least in four different ways:

Matter falling into the black hole will emit radiation. In part, because matter is greatly accelerated in the end; as a sort of "death scream", it will emit x-rays. Also, because it can interact with other matter, and get heated up.

Its gravitational attraction. Some stars have been observed moving around an invisible center, in the center of our galaxy. This allowed a mass estimate, of the galactic black hole, of some 3 million solar masses. Bigger galaxies have black holes with billions (U.S. billions) of solar masses!

Gravitational lenses: The gravitation will bend light-rays of objects that are farther away.

While General Relativity predicts that a black hole can gain mass, but not lose it, theoretical considerations, by Stephen Hawking, predict certain weird effects close to the border (event horizon) of the black hole. The black hole would indeed lose mass gradually. But the time to evaporate would be much more than the current age of the Universe; something like 10^64 years for a stellar black hole, and 10^100 years for a galactic black hole! The corresponding radiation would be extremely weak, and in the present state of the Universe, the black hole would consume matter much faster than it would evaporate it.

>Although black holes may be relatively small in their dimensions in comparison to their mass, they might contain a tremendous amount of matter.

The diameter of the "event horizon", which is usually simply called the diameter of the black hole, would be in a linear proportion to its mass. However, the huge black hole in the center of our Milky Way would still only have a diameter of a few million km.

>If matter is being consumed by black holes, and compacted into tiny object in comparison to their mass, what takes the place of the matter that previously occupied space within it normal dimensions of the universe. It may be that the universe is shirking as matter is pulled into black holes.

Please note that neither the total mass nor the gravitational attraction is changed by the fact that matter is "sucked up" by a black hole. If our Sun would suddenly convert to a black hole (which is unlikely, since it doesn't have isn't enough mass), it would continue attracting Earth with the same force as now, and Earth would continue to go arround the former Sun - lifeless, for lack of sunlight.

It is commonly accepted, however, that the Universe is expanding. This is quite obvious from the Doppler Effect of distant galaxies: the fact that they are receding manifests itself in a change of frequency of the light we receive.


(Some places to explore more about black holes, and other astronomical topics, are www.physicsweb.org, and Scientific American (www.sciam.com).)

Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)