Tuesday, March 29, 2011

Inflation May Need Air

In the late 1970's, when rising prices were on everyone's mind, Alan Guth and others proposed that the universe had also suffered from inflation. According to inflation, when the universe was only 10^{-33} seconds old it expanded at warp speed, many times faster than light. Though it appeared to solve some puzzles in cosmology, inflation would violate both the First Law of Thermodynamics (conservation of energy) and Relativity's stipulation that nothing travels faster than light.

To power inflation, physicists had to infer repulsive "scalar fields" or "inflatons." None of these imaginary forces has ever been observed in nature. Inflation can never be demonstrated by experiment--humans can not time-travel to the first 10^{-33} seconds to observe inflation, and no human experiment can approach the titanic energies near the Big Bang. Nevertheless, inflation theories have been a cottage industry for 3 decades.

In the cover story of this month's SCIENTIFIC AMERICAN, cosmologist Paul Steinhardt asks:

The Inflation Debate: Is the theory at the heart of modern cosmology fundamentally flawed?

"In brief: Cosmic inflation is so widely accepted that it is often taken as established fact. The idea is that the geometry and uniformity of the cosmos were established during an intense early growth spurt.

"But some of the theory’s creators, including the author, are having second thoughts. As the original theory has developed, cracks have appeared in its logical foundations.

"Highly improbable conditions are required to start inflation. Worse, inflation goes on eternally, producing infinitely many outcomes, so the theory makes no firm observational predictions."

Steinhardt, one of inflation's founders, has abandoned the idea and is now advocating a cyclic universe. Other alternatives have also appeared. A cosmology where light was much faster in the early universe would sidestep the problem of expanding faster than light. Varying c would solve the same problems that inflation claims--why the universe appears uniform and why it is at a critical density. For inflation to work, the overall density must be tuned to a very precise value. According to GM=tc^3 the "critical" density is the stable density.

Inflation appeared to solve cosmological puzzles and provided much food for thought. Though a useful step, inflation can never be proven. Unlike inflation, a GM=tc^3 model makes a surprising and testable prediction--light is still slowing down at a tiny rate. Evidence for a "c change" may be here with us today.

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4 Comments:

Blogger Kea said...

Enough hot air, already. I was disappointed with the concluding remarks, which focus only on his own ideas.

7:39 PM  
Blogger L. Riofrio said...

Always great to hear from you. Posts on this subject draw the most negative comments from inflation cultists. Could they have finally shut up?

5:50 PM  
Blogger qraal said...

Hi Louise
Have you seen this paper by Lorenzo Iorio?

http://arxiv.org/abs/1102.4572

Abstract...

Empirical explanation of the anomalous increases of the astronomical unit and of the lunar eccentricity

Lorenzo Iorio
(Submitted on 22 Feb 2011)
Both the recently reported anomalous secular increase of the astronomical unit, of the order of a few cm yr^-1, and of the eccentricity of the lunar orbit e_ = (9+/-3) 10^-12 yr^-1 can be phenomenologically explained by postulating that the acceleration of a test particle orbiting a central body, in addition to usual Newtonian component, contains a small additional radial term proportional to the radial projection vr of the velocity of the particle's orbital motion. Indeed, it induces secular variations of both the semi-major axis a and the eccentricity e of the test particle's orbit. In the case of the Earth and the Moon, they numerically agree rather well with the measured anomalies if one takes the numerical value of the coefficient of proportionality of the extra-acceleration approximately equal to that of the Hubble parameter H0 = 7.3 10^-11 yr^-1.

11:50 PM  
Blogger L. Riofrio said...

Nice hearing from you too, graal. The Lorio paper was linked to in my March 19 post, Supermoon Tonight. Just as Ole Roemer used Jupiter's moons to measure the speed of light, and Mercury's precession was used to prove Relativity, anomalies in orbits are significant for Physics.

7:39 AM  

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