Light fantastic (14 billion year old light imaged)

Washington: Astronomers today published images of the universe in its earliest stages that were captured at an observatory high in the Chilean Andes, reinforcing the Big Bang theory of the origin of galaxies.

The images show the oldest light ever emitted by the universe in the closest detail ever observed, and were taken by the Cosmic Background Imager (CBI) operated by the California Institute of Technology (Caltech) in Pasadena.

Researchers were able to detect minute variations in the cosmic microwave background, radiation that has travelled to earth over almost 14 billion years.

A map of temperature fluctuations shows the first tentative seeds of matter and energy that would later evolve into clusters of hundreds of galaxies, according to the scientists.

The measurements provide evidence of part of the Big Bang theory - that of inflation, which speculates that the universe underwent a violent expansion in its first micro-moments.

After about 300,000 years the universe cooled enough to allow the seeds of matter to form and became "transparent," allowing light to pass through, with remnants of that energy observed by the imager.

The data also provided new information about the repulsive force called "dark energy" that appears to defy gravity and force the universe to accelerate at an ever-increasing pace.

"We have seen, for the first time, the seeds that gave rise to clusters of galaxies, thus putting theories of galaxy formation on a firm observational footing," said team leader Anthony Readhead of Caltech.

"These unique high-resolution observations provide a new set of critical tests of cosmology, and provide new and independent evidence that the universe is flat and is dominated by dark matter and dark energy," he added.

Readhead, along with Caltech colleagues Steve Padin and Timothy Pearson, plus others from Canada, Chile and the United States, worked to generate the measurements of the cosmic microwave background.

"This is basic research at its finest and most exciting," said NSF director Rita Colwell. "Each new image of the early universe refines our model of how it all began."

Numerous researchers believe that 95 per cent of the mass of the universe is invisible, made up of 50 per cent vacuum and 45 per cent dark matter.

Using a far superior resolution, the CBI has been working on research begun by the US Cosmic Background Explorer (COBE) satellite which 10 years ago first highlighted evidence of fluctuations of the first light of the cosmos.

The observatory, located in the world's driest desert at Atacama, Chile is some 5,080 metres above sea level. Extremely low humidity there optimises the equipment's observation capabilities.

Five papers on the CBI data were submitted today to the Astrophysical Journal for publication.

If there's one thing that the observers all must agree upon, it's causality.

Darn it, I can't remember the proof. And I've been thinking about it all weekend. I used to be able to reproduce it at the drop of a hat. It was quite simple, not unlike the proof of the time dilation equation in special relativity that's taught to every high-school physics student: i.e., you start with a boxcar traveling near c, and observers inside and outside of the boxcar. But I can't remember the trick for changing it from a proof involving t₁ and t₂ for the two observers to a proof involving the observed order of events. Of course, there is always the possibility I completely misunderstood the implications of the proof. But I doubt it since it was just high-school algebra. Anyway, if I ever remember it I'll post it and let you rip it apart. :-)

(There were some restrictions. I do remember that. Thanks again for even talking to me about this.)

Oh . . . I think I remember now how it goes! Suppose you've got a 100ft-long boxcar going due East at a uniform velocity very close to c. A man inside flips a switch that sends two beams of light out in opposite directions, East and West. The source of the light is located 51 feet from the West end of the boxcar and 49 feet from the East end.

Therefore, the man inside the boxcar will observe the light beams strike opposite ends of the car at different times; namely, he'll see the the westbound beam arrive at the end of the boxcar about a nanosecond after the eastbound beam. The eastbound beam wins.

But for a man outside the boxcar the "order" of these two events is reversed, depending, of course, on how fast the boxcar is going. In other words, the westbound beam can win.

The time order of these events is relative to who is doing the observing.

Physicist, I know your time is valuable, and I do not want you to waste a second of it on this if you don't want to. I just wanted to tell you of the so-called "proof." I know you've mentioned a "time like ordering" and a "space like ordering" and I think I've got to think about that some more. Plus I've found a long article that I think will help me figure out where my own train has jumped the tracks. :-)

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