Space Telescope Information

Josh Stoll · Posted: Wed Jul 14, 2004 2:46 pm Post subject: Space Telescope Information

Has anyone found certain information from websites about the findings of the Space Telescope. When I say "findings" I mean what they have seen in Space to further help the development of Evolution, or any Theory at that matter. I got this quote from a website:

admin · Posted: Wed Jul 14, 2004 8:10 pm Post subject:

http://www.windows.ucar.edu/tour/link=/headline_universe/hubble_constant.html

After eight long years, the Hubble Space Telescope Key Project Team finally revealed what they believe is the real Hubble Constant. The Hubble Constant is the speed which the Universe is expanding at. For over 70 years, scientists have argued over the exact number.

Astronomers are able to use the constant to "work backwards", in order to find the age of the Universe. Now that the Hubble team has found Hubble's Constant to be 70 kilometers per second per megaparsec, they have determined the age of the Universe to be 12 billion years old. At one time, scientists differed on the value of the constant by a factor of 2. Now, the constant has been measured with an error of only 10 percent.

The Hubble team used a certain type of star called a Cepheid variable star. A Cepheid is a special pulsating star that can be used to make precise distance measurements. Over 800 Cepheids were found during the 10 year project.

Finding the Hubble Constant was one of three original goals set by astronomers when the telescope was first launched in 1990. The telescope is named after Edwin Hubble, the first to believe the Universe is expanding.

Arthwollipot · Posted: Thu Jul 15, 2004 4:03 am Post subject:

The Space Telescope has done practically nothing to further evolutionary biology - which is after all a theory of biology. The Telescope has, however, caused great advances in astronomy, astrophysics and cosmology, which cannot be ignored.

primitive hominid · Posted: Thu Jul 15, 2004 8:14 am Post subject:

Another interesting observation is that when one looks at the distribution of red shifts and tries to get a value for the Hubble constant, it appears to have changed with time. It now appears that the rate of expansion of the universe is increasing. There appears to be some sort of repulsive force, which is being labeled as "dark energy", which scientists are trying to understand.

Arthwollipot · Posted: Mon Jul 19, 2004 2:46 am Post subject:

The apparent acceleration in the expansion in the universe is accommodated in General Relativity by Einstein's Cosmological Constant.

Basically when he formulated General Relativity, the theory which accurately describes gravity, he discovered that the equations implied a non-static universe. It had to be either expanding or contracting, it couldn't be standing still. Einstein inserted a term into General Relativity called the Cosmological Constant, in order to accommodate his conviction of a static universe.

When Edwin Hubble discovered in the 1920s that the universe was, in fact, expanding, Einstein removed the Constant, noting that it was the "greatest blunder" of his life.

In the last ten years it has been discovered that the expansion of the universe has been accelerating, the Cosmological Constant has been revived. Basically a non-zero Cosmological Constant is a force that works against gravity, as a repulsive force, pushing all matter away from all other matter. When finely tuned, it can indeed allow General Relativity to describe a static universe. But with a different value it can describe the accelerated expansion that has been observed.

Until recently (by cosmological standards) this has not been strong enough to counter the force of gravity. But as the universe expanded, and matter was pushed further and further apart, the attractive force of gravity became weaker and weaker, allowing the Cosmological Constant to outweigh it.

The Cosmological Constant, which is a mathematical entity, is explained in reality by a force known as Dark Energy.

Remember that this is all still at the bleeding edge of cosmological physics, and there is a lot more still to be worked out by the planet's best brains.

primitive hominid · Posted: Mon Jul 19, 2004 8:53 am Post subject:

One small addendum:

as the universe expands, the repulsive force seems to increase in strength. I don't know enough about it to say whether this is a property of the General Relativistic cosmological constant, or whether it is strictly an observational fact.

Eventually, the expansion of the universe, extrapolating this trend far, far into the future, will be so great that gravity will not be able to keep plants around their (by then dead) stars, and eventually even the atoms themselves will fly apart under this expansion.

admin · Posted: Mon Jul 19, 2004 10:29 pm Post subject:

I wish I could get you guys on a retreat for a week, this is fascinating.

Arthwollipot · Posted: Wed Jul 21, 2004 9:24 pm Post subject:

It's not that the repulsive force is getting stronger - it's just that the gravitational force is getting weaker. Remember the inverse square law - the further the distance between the masses, the weaker the gravitational force. So as the expansion of the universe pushes the masses apart, the gravitational force between them gets weaker, allowing the repulsive force (represented by the Cosmological Constant) to push them apart even faster.

Note - we are talking about large masses such as galaxies, not small masses like planets and stars, which are not greatly affected by this.

Arthwollipot · Posted: Wed Jul 21, 2004 9:27 pm Post subject:

primitive hominid · Posted: Thu Jul 22, 2004 8:50 am Post subject:

Arthwollipot · Posted: Thu Jul 22, 2004 7:55 pm Post subject:

Yes, I do remember seeing something like that. My main point is that the repulsive force does not require any major revolutions in our current understanding. We still do not know what causes the repulsive force, but we know how to account for it. I would have to do a lot more reading.