Sunday, August 06, 2006

The Dark Side

Before I spend a week writing about useful things, here continues the story of "dark energy."

"Two groups" studying the same phenomenon of Type Ia supernovae, and both using the National Optical Astronomy Observatory (NOAO) telescopes in Cerro Tololo, Chile simultaneously announced dark energy in 1998. This was hailed by SCIENCE magazine as "Breakthrough of the year."

The largest group in Berkeley, the Supernova Cosmology Project, next planned a Supernova Acceleration Probe (SNAP). This would be a 2-meter infrared telescope located at L2, on the other side of the Moon. SNAP would find thousands of supernovae to further refine the "dark energy equation of state." This project would cost hundreds of millions of dollars.

At a conference in Tucson, Arizona in March 2004; another group led by NOAO's Tod Lauer announced a rival proposal. Their Dark Energy Space Telescope (DESTINY) was touted as a lower-cost alternative. Just last week NASA chose this concept for further funding. Below are concepts for SNAP (left) and DESTINY (right).


They look the same, don't they? The SNAP team should have taken out a patent. The main difference is that SNAP would have a 2-meter mirror and DESTINY a 1.65-m mirror.



The smaller mirror leads to a spacecraft with about half the mass, with corresponding economies of fuel and launch vehicle.

Without substantial changes, it is difficult to see how the SNAP proposal can fly when a lower-cost alternative is available.

Neither project may fly anytime soon, for the space astronomy budget is dominated by the James Webb Space Telescope. JWST will look at similiar infrared wavelenghts to SNAP and DESTINY, and can also be used to seek high-redshift supernovae.

Assuming that either of these missions get off the ground, they will not capture a single wave or particle of 'dark energy' to prove it exists. All they will do is refine the magnitude-redshift curve in an attempt to distinguish between the myriad models for DE. Even if "dark energy" exists, it has no conceivable practical value. It would be so diffuse in Space that it could not power your car or even your cellphone. Speculation about repulsive "dark energy" has not led to understanding, but to a divergence of possible solutions.

Those of you who hold real jobs and pay real taxes, do you wish to spend hundreds of millions to fund "dark energy" experiments? Perhaps you see why physics has lost respect among the wider public.

If one wishes to investigate whether c has changed, all one needs is an inexpensive experiment for independently measuring c. Soon you will hear about experiments which do exactly that.

8 Comments:

Blogger Mahndisa S. Rigmaiden said...

08 06 06

Hello Louise:
Interesting article. I didn't realize those funding issues were going on. I think it would be worthwhile to fund a dark matter exploration, perhaps after other issues have been explored in greater detail.

Frankly, I am concerned about the phonomenological correctness of string theory and LQG (now AQG) and would like to view experiments to test those theories. ehheehhheeh This article (PDF) from the arxiv figures out a way to do that:
"A possible experimental test
of quantized gravity"
, by P. Salzman and Carlip.


Have a great day:)

12:00 AM  
Anonymous Count Iblis said...

Quasar9,
See here :)

5:50 AM  
Blogger Mahndisa S. Rigmaiden said...

08 07 06

Whoa Louise:
That article that Count Iblis cited was seriously interesting. Apparently you and the author are in violent disagreement. I think I will do a post about this issue, as it is contentious in the physics world and ask for your comments (that is if you have the time):)

7:43 AM  
Blogger L. Riofrio said...

Mahndisa, having studied in the Bay Area we are fortunate to know the people involved in supernova research. I do consider them friends and wish them all success. Hopefully we will get to discover supernovae from Space. It is disturbing when these research groups include no women, but my advice is intended to aid them.

If hc is really constant, my other friends in Australia may not find any change in alpha. It is a huge step forward that c change is a subject of discussion instead of being dismissed. Now we have an author claiming constant c being shut out of Nature and forced to post on hep-th! Tamara Davis is a woman, studied in Australia, and is a real cool person.

Q9, c represents the very relation between Space/Time. Meters per second, it's a velocity. Changing c does not affect the gravitational constant G holding the planets in orbit. If "dark energy" is 2/3 of the Universe, why doesn't DE affect planetary orbits?

Just as when building a house you can consider Earth to be flat, for our experience it is reasonable to consider c constant. The change is so small you can only detect it in the very distant past, as shown by high-redshift supernovae. Since c was higher, those objects are farther away than previously thought.

Good link, Iblis. That was a character from classic Galactica, correct? As Prince of Darkness, Count Iblis would be an authority on "dark energy". Perhaps he is even now leading cosmologists to their doom...

7:55 AM  
Blogger Kea said...

Ah, the old McDuff. Keeps coming up, that one.

2:50 PM  
Anonymous Count Iblis said...

Louise, if you read my blog, you'll understand that the "character from classic Galactica" really exists, or at least a near exact copy of him. :)

3:58 AM  
Anonymous Anonymous said...

Excellent, love it! »

1:01 AM  
Anonymous Medicine said...

This project would cost hundreds of millions of dollars.

1:16 AM  

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