Friday, August 15, 2008

'Dark Energy' Bad For Spelling

This is an actual NASA Procurement Notice Title:

DESTINY MISSION CEONCPET FOR THE JOINT DARK ENERGY MISSIN - JDEM

DESTINY (Dark Energy Space Telescope) is one of three competing concepts, along with SNAP and ADEPT for a DE mission. The competing teams have yet to agree on a concept, and are still not sure how the project will be funded. The hypothesis of a repulsive "dark energy" leads to a divergence of solutions, which will keep theorists in grants but not tell us anything about the universe.

In his December Physicsworld article, Lwrence Krauss describes the observational challenge:

"Existing data show that –1.2 < w < –0.8, which means that we know w is very close to the cosmological-constant value of –1. But since we have no theory whatsoever to guide us if w turns out not to equal –1, either today or earlier in cosmic history, we have to allow for the possibility that w varies arbitrarily with time. When this theoretical uncertainty is combined with the likely systematic uncertainty of observations — for example due to difficulties in determining the absolute brightness of supernovae — it will be very hard to tell whether the equation of state of dark energy actually deviated from –1 at any time in the past.

"Earlier this year I, along with Dragan Huterer at the University of Chicago and Kate Jones-Smith of Case Western Reserve University, calculated that even if 3000 supernova observations were made with a measurement accuracy slightly better than anything that has been possible thus far, then the constraints on the measured value might improve by at most a factor of 2 once the theoretical uncertainty in w is incorporated. In other words, –1.1 < w < –0.9 (New J. Phys. 9 141).

"But let us say, for the sake of argument, that the true value of the equation of state parameter is w = –0.96. Then, even if we are able to improve the existing uncertainty in w by a factor of 10 using a variety of proposed techniques beyond simply measuring distant supernovae, a value of w = –1 will only be two standard deviations away from the best fit value (which may not even correspond to w = –0.96). Unfortunately, such confidence intervals occur routinely in physics and, while suggestive, are not sufficient to claim a discovery.

As readers know there IS a theory. Three truly independent experiments: Type Ia supernovae, lunar laser ranging and the 'Faint Young Sun" show not just that c slows, but that it slows at exactly the rate GM=tc^3 predicts. Once we know what to look for, finding a signal in the data becomes easy.

The epicycles of "Dark Energy" will take a long time to die out. Billion-dollar Space missions are planned to find its "equation of state." Careers, reputations and even hoped-for trips to Stockholm now centre around its existence. Scientists have vested interest in promoting DE. Their reputation continues to erode with their spelling.

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2 Comments:

Anonymous John Merryman said...

Do you believe the validity of special relativity?

11:48 PM  
Blogger L. Riofrio said...

Absolutely, you can derive the equations of SR starting from r = ct. Try it. SR says that c is constnat regardless of location, not time.

8:09 PM  

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