(Once again, the evidence for either an “accelerating Universe” or a changing speed of light. Low redshifts increase linearly with distance, showing that the Space/Time expands. High redshifts increase non-linearly, leading to speculation about repulsive energies. Supernova redshifts are the only direct evidence of acceleration. The cosmic microwave background, dating from a time just 380,000 years after the Big Bang, tells us nothing about acceleration. Prediction of GM=tc^3 and a slowing speed of light still fits the data precisely.)
This morning's NEW YORK TIMES science section is almost a death knell for "dark energy" science:Quest for Dark Energy May Fade to Black
"An ambitious 1.6 billion spacecraft that would investigate the mysterious force that is apparently accelerating the expansion of the universe — and search out planets around other stars, to boot — might have to be postponed for a decade, NASA says, because of cost overruns and mismanagement on a separate project, the James Webb Space Telescope. The news has dismayed many American astronomers, who worry they will wind up playing second fiddle to their European counterparts in what they say is the deepest mystery in the universe."
How did scientists get into this mess? Since 2006 this little blog has chronicled the disorganised and ill-starred story of "dark energy" and how it has been bad, very bad for science. The obsession with hypothetical DE has divided science into competing camps and pushed other promising projects out of the way. Despite the warnings, DE has not ripped apart the galaxies but has ruined science.
In 1998 two groups, the Supernova Cosmology Project and High-Z Supernova Search, were looking at the same phenomenon, redshifts of Type Ia supernovae. Though scientists haven't figured out what powers supernovae, the luminosities of Type Ia were considered constant. By seeking out supernovae in distant galaxies, physicists thought to determine how fast the universe is expanding. To their surprise high redshifts appeared to curve upward, as if the universe were accelerating.
Since both groups were looking at the same phenomenon, there was pressure to publish first. A junior member of the latter group published a paper claiming that the universe wa pushed by a repulsive "cosmological constant." His office was in Campbell Hall at UC Berkeley, about 500 meters from Lawrence Berkeley Lab and headquarters of the first group. Some months after he published, the first group published a paper with the same conclusions. Though both groups were closely located, looking at the same phenomenon and knew of each other's work, they were called "independent."
To spread, even a bad idea needs good press. SCIENCE magazine put acceleration on its cover as "Breakthrough of the Year" with a cartoon of Albert Einstein. In their lectures, the supernova hunters often showed this cover as if it were some sort of proof. Approbation of others can be a substitute for certainty. The supernova hunters shared the 1 million dollar Shaw prize and the 500,000 dollar Gruber Cosmology Prize. The cosmological constant, renamed "dark energy" when it was found not to be constant, seemed to be the hottest ticket in science.
Flush from their "breakthrough," scientists became even more ambitious. In 1999 one group proposed a Supernova Acceleration Probe (SNAP), a 2-meter infrared telescope at the Sun-Earth L2 point. From this vantage point a million miles from Earth SNAP would theoretically find thousands of supernovae, seeking the unseen "dark energy." Even if SNAP were successful, it would not return a single wave or particle of DE to prove it exists. It would simply find an "equation of state" that could be explained by a changing speed of light.
Hypothetical "dark energy" has not led to solutions, but a divergence of speculative ideas. Every theorist came up with their own pet theory. Whenever a new theory came along, all the others could agree it was wrong. Researchers could not even agree on a mission concept. Within several years the SNAP proposal was joined by DESTINY, a similar proposal with a 1.5 meter aperture, and yet another proposal called ADEPT. Each proposal had its own Principal Investigator (PI) and its own set of supporters, all competing for the same funding.
Searching for "dark energy" began to crowd out other priorities. At first it was just one Space mission in a NASA program called Beyond Einstein. The astrophysics program also included X-Ray observatories, gravitational wave experiments, and an undefined inflation probe. When funding became tight, the National Academies held a series of meetings to set priorities. Finding "dark energy" was considered so important that other projects were pushed to the back of the line, not to fly in this decade.
In September 2008 NASA and DOE tried to combine the 3 proposals into a Joint Dark energy Mission (JDEM). The PI hopefuls were reduced to advisors in the new plan. The merged mission looked so expensive that NASA asked the European Space Agency to contribute. DOE, feeling jilted for the Europeans, dropped out and pursued their own experiment. When all this mate-swapping was finished, the agencies were back to three competing proposals. A NATURE article said of JDEM, "This is an example of a satellite blowing up before it gets built" while calling DE a fudge factor.
In August 2010 the National Academies officially endorsed a new combined mission, Widefield Infrared Survey Telescope. WFIRST would search for extrasolar planets, and look for "dark energy" on the way. Just 3 months later NASA announced that their flagship mission, the James Webb Space Telescope, was years behind schedule and needed billions more to fly. With JWST eating up the astrophysics budget, WFIRST would not fly until the 2020's if ever.
Most scientists quietly doubt that "dark energy" exists. Despite all the favorable press, the idea has never caught on with the public. Even journalists often confuse "dark energy" with "dark matter." DE is largely a hypothesis of physicists driven into cosmology by the lack of Physics funding. Eventually DE is likely to fade into memory like ether, phlogiston and epicycles. It will not cause the universe to rip apart, but it continues to rip apart science.
The explanation of cosmic "acceleration" is so simple that a child could understand it. Redshifts are proportional to the speed of light c. Rather than the universe accelerating, we have observed c slowing down. A changing c can be corroborated by direct measurements over a long baseline, like the distance to the Moon. Long before SNAP, JDEM, or WFIRST will ever get a chance to fly, there will be "c change" in physics.
Labels: dark energy