Hubble telescope makes new discovery

AP on Yahoo ^ | 11/16/06 | Matt Crenson - ap

[NormsRevenge]

NEW YORK - The Hubble Space Telescope has shown that a mysterious form of energy first conceived by Albert Einstein, then rejected by the famous physicist as his "greatest blunder," appears to have been fueling the expansion of the universe for most of its history.

This so-called "dark energy" has been pushing the universe outward for at least 9 billion years, astronomers said Thursday.

"This is the first time we have significant, discrete data from back then," said Adam Riess, a professor of astronomy at Johns Hopkins University and researcher at NASA's Space Telescope Science Institute.

He and several colleagues used the Hubble to observe 23 supernovae — exploding white dwarf stars — so distant that their light took more than half the history of the universe to reach the orbiting telescope. That means the supernovae existed when the universe was less than half its current age of approximately 13.7 billion years.

Because the physics of supernova explosions is extremely well-known, it is possible for the astronomers to gauge not just their distance, but how fast the universe was expanding at the time they went off.

"This finding continues to validate the use of these supernovae as cosmic probes," Riess said.

He and his colleagues describe their research in a paper that is scheduled for publication in the Feb. 10 issue of Astrophysical Journal.

The idea of dark energy was first proposed by Einstein as a means of explaining how the universe could resist collapsing under the pull of gravity. But then Edwin Hubble — the astronomer for whom the NASA telescope is named — demonstrated in 1929 that the universe is expanding, not a constant size. That led to the big-bang theory, and Einstein tossed his notion on science's scrap heap.

There it languished until 1998, when astronomers who were using supernova explosions to gauge the expansion of the universe made a shocking observation. It appeared that older supernovae, whose light had traveled a greater distance across space to reach the Hubble telescope, were receding from Earth more slowly than simple big-bang theory would predict. Nearby supernovae were receding more quickly than expected. That could only be true if some mysterious force were causing the expansion of the universe to accelerate over time.

Cosmologists dubbed the force "dark energy," and ever since they've been trying to figure out what it is.

"Dark energy makes us nervous," said Sean Carroll, a theoretical physicist at the California Institute of Technology who was not involved in the supernova study. "It fits the data, but it's not what we really expected."

Answers may come once NASA upgrades the Hubble Space Telescope in a space shuttle mission scheduled for 2008. NASA and the Department of Energy are also planning to launch an orbiting observatory specifically designed to address the mystery in 2011.

Dark energy could be some property of space itself, which is what Einstein was thinking of when he proposed it. Or it could be something akin to an electromagnetic field pushing on the universe. And then there's the possibility that the whole thing is caused by some hitherto undiscovered wrinkle in the laws of gravity.

[Prophet in the wilderness]

" Because the physics of supernova explosions is extremely well-known " .... until the newest future discovery proves them all wrong.

[Southack]

First of all, if "dark energy" is accelerating universal expansion, why don't we see a uniform acceleration? Second, why don't we see this impact on a micro level?

Third, what do the equations and data say? We know, for instance, that Gravity is inversely proportional to distance.

Well, if Gravity has anything to do with universal expansion, then that inverse proportionality will be evident in the modeling equations and research data.

Is it?!

[spinestein]

[I think relativity is mostly right. I think this article is bunk.]


This article was written by a scientifically illiterate journalist in an attempt to take an inherently complicated and difficult to understand paper and present it to the public in a watered down and dumbed down version, no matter how many irrelevant Einstein anecdotes need to be introduced or how many misleading, but interesting, metaphors have to be invented.

This is typical of the MSM (in this case the AP) and the only way to fairly judge this is to wait until the paper comes out in February and read it, assuming one already has a thorough understanding of the relevant physics and the topic of cosmology itself (and very few people do). I majored in physics in college and I'm pretty sure I wouldn't have the knowledge required to check the validity of the arguments put forth.

[kinoxi]

Okay...

[spinestein]

["Because the physics of supernova explosions is extremely well-known " .... until the newest future discovery proves them all wrong.]


This is a common misunderstanding of how the process of science works to advance knowledge, and it's an error based on the assumption that an established theory which is refined in order to improve its compliance with observed phenomena must have been fundamentally wrong to begin with. An example of this is the established theory of Newtonian mechanics describing how objects move through space, modified by relativity theory so as to explain small anomalies of Newtonian theory observed under unusual conditions, such as near the speed of light. Newtonian theory is here being refined, not replaced, and few would criticize that the Newtonian laws of motion which millions of people find useful everyday, are now invalid.

[kinoxi]

Newtonian theory is replaced in your assessment.

[MonicaG]

Very fascinating. Thanks, Physicist.

[TigersEye]

And since no chimp ever yet thought of God.. will never find out..

If there were no minds to think of God would God exist?

[spinestein]

I clearly came to the opposite conclusion in my post when I said that Newtonian theory was refined, not replaced, by relativity theory and I would risk becoming blatantly pedantic to try to elaborate further. But that's never stopped me before, so....

Use this analogy: Someone invents the wheel and axle and a grand concept in transportation is born. Then someone else later attaches a horse to the front and this improves the concept allowing people to move about faster that humans can run. An internal combustion engine is then installed in place of the horse and this also is seen as an improvement (unless your name is AlGore) allowing travel to and from jobs at great distances and permitting goods to be transported thousands of miles in a few days. Currently, the wheel and axle concept of transportation is undergoing many additions and refinements such as hybrid electric motors and GPS navigation, yet at no time past or present was the underlying theory determined to be invalid or flawed. Even when the horse was replaced by an engine this didn't have anything to do with the validity of the underlying theory, just a change in practical application.

This relates to the article because some critics are asserting that expanding universe theory must be wholly invalid if the observed and measured expansion of the universe deviates even a tiny amount from the value predicted by the currently incomplete theories. This is fallacious, as if a small, as yet unexplained deviation in the observed rate of expansion means that the universe isn't really expanding at all.

[spinestein]

[If there were no minds to think of God would God exist?]


I would guess the answer is 'no'.

[GSlob]

Dark energy? hillary is powered by dark energy. And similar subjects can be conveniently studied on earth - no Hubble is necessary.

[kinoxi]

It is entirely replaced. The math is easier at lower speeds, but it is never better to use. Check your facts. Newton has been verified as wrong. Relativity has not. No more analogies please.

[monkapotamus]

[timer]

Perhaps dark energy is "tired light", ie, photons don't die, they become this burbling little sea of the ZPE. Also, deceleration and gravity are both over running matter waves, which is TIME; which you know as the collapse of the wavefunction.

[spinestein]

[It is entirely replaced. The math is easier at lower speeds, but it is never better to use. Check your facts. Newton has been verified as wrong. Relativity has not.]


I don't know where you're getting this from. Newtonian calculations are used routinely by engineers to get the correct solutions to practical problems all the time. In fact it's very rare for anyone to use relativistic calculations for any problem that isn't entirely hypothetical as it's never needed in everyday encounters with physics or engineering. I would suggest you check your facts before you post. Good night.

[M. Espinola]

LOL

[Caipirabob]

LOL! The stuff I see here...

[jeffers]

It seems reasonable to me to expect that an accretion limit exists for black holes. Past a certain "compression" limit, expansion forces outweigh gravity, hence the big bang and a cyclical universe.

I guess its possible that at lower and lower densities, another shelf (force interaction resulting in a net increase in resultant acceleration) is crossed, resulting in expansion acceleration, but that seems almost as convenient as Einstein's cosmological constant.

Eliminating that leaves two general categories of explanation, an intrinsic property of space-time-mass-energy which our current understanding of same, especially space curvature, doesn't currently permit, or an unsuspected force.

I like space-time-mass-energy better. I've been working on a solution set where mass is replaced by rolled up space, and energy is dynamic rolling and unrolling of space, but it's a long way before math.

Still anomalies such as this are clues, and we may be approaching a point where solving a single clue yields orders of magnitude better understanding across the spectrum of disciplines.

Fascinating stuff.

Eliminating

[Toadman]

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