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Rover looks into crater
The spectacular high-resolution, color panorama from the Mars rover Opportunity at the edge of Endurance Crater is presented with expert narration by Steve Squyres, the mission's lead scientist. (2min 08sec file)
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The Columbia Hills
Explore the Columbia Hills at Gusev Crater where Spirit is headed in this computer-generated movie using imagery from orbit. Expert narration by Amy Knudson, science team collaborator. (3min 11sec file)
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Thursday's Mars briefing
The Mars rover Opportunity's arrival at Endurance Crater and Spirit's trek to the Columbia Hills are topics in this news conference from May 6. (42min 12sec file)
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Tale of Soyuz ride
Expedition 8 commander Mike Foale describes what it is like to land in a Soyuz capsule and reflects on his half-year mission aboard the International Space Station in this post-flight interview. (23min 37sec file)
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Clues to theory may be visible in Big Bang aftermath
Posted: May 14, 2004

Scientists studying the Big Bang say that it is possible that string theory may one day be tested experimentally via measurements of the Big Bangs afterglow.

Richard Easther, assistant professor of physics at Yale University discussed the possibility at a meeting at Stanford University Wednesday, May 12, titled Beyond Einstein: From the Big Bang to Black Holes. Easthers colleagues are Brian Greene of Columbia University, William Kinney of the University at Buffalo, SUNY, Hiranya Peiris of Princeton University and Gary Shiu of the University of Wisconsin.

String theory attempts to unify the physics of the large (gravity) and the small (the atom). These are now described by two theories, general relativity and quantum theory, both of which are likely to be incomplete.

Critics have disdained string theory as a philosophythat cannot be tested. However, the results of Easther and his colleagues suggest that observational evidence supporting string theory may be found in careful measurements of the Cosmic Microwave Background (CMB), the first light to emerge after the Big Bang.

In the Big Bang, the most powerful event in the history of the Universe, we see the energies needed to reveal the subtle signs of string theory,said Easther.

String theory reveals itself only over extreme small distances and at high energies. The Planck scale measures 10^-35 meters, the theoretical shortest distance that can be defined. In comparison, a tiny hydrogen atom, 10^-10 meters across, is ten trillion trillion times as wide. Similarly, the largest particle accelerators generate energies of 10^-15 electron volts by colliding sub-atomic particles. This energy level can reveal the physics of quantum theory, but is still roughly a trillion times lower than the energy required to test string theory.

Scientists say that the fundamental forces of the Universe gravity (defined by general relativity), electromagnetism, "weak" radioactive forces and "strong" nuclear forces (all defined by quantum theory) were united in the high-energy flash of the Big Bang, when all matter and energy was confined within a sub-atomic scale. Although the Big Bang occurred nearly 14 billion years ago its afterglow, the CMB, still blankets the entire universe and contains a fossilized record of the first moments of time.

The Wilkinson Microwave Anisotropy Probe (WMAP) studies the CMB and detects subtle temperature differences, within this largely uniform radiation, glowing at only 2.73 degrees Celsius above absolute zero. The uniformity is evidence of inflation,a period when the expansion of the Universe accelerated rapidly, around 10^-33 seconds after the Big Bang. During inflation, the Universe grew from an atomic scale to a cosmic scale, increasing its size a hundred trillion trillion times over. The energy field that drove inflation, like all quantum fields, contained fluctuations. These fluctuations, locked into the cosmic microwave background like waves on a frozen pond, may contain evidence for string theory.

Easther and his colleagues compare the rapid cosmic expansion that occurred just after the Big Bang to enlarging a photograph to reveal individual pixels. While physics at the Planck scale made a "ripple" 10^-35 meters across, thanks to the expansion of the Universe the fluctuation might now span many light years.

Easther stressed it is a long shot that string theory might leave measurable effects on the microwave background by subtly changing the pattern of hot and cold spots. However, string theory is so hard to test experimentally that any chance is worth trying. Successors to WMAP, such as CMBPol and the European mission, Planck, will measure the CMB with unprecedented accuracy.

The modifications to the CMB arising from string theory could deviate from the standard prediction for the temperature differences in the cosmic microwave background by as much as 1%. However, finding a small deviation from a dominant theory is not without precedent. As an example, the measured orbit of Mercury differed from what was predicted by Isaac Newton's law of gravity by around seventy miles per year. General relativity, Albert Einstein's law of gravity, could account for the discrepancy caused by a subtle warp in spacetime from the Sun's gravity speeding Mercury's orbit.

Mars rover collectible patch

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This commemorative patch celebrates NASA's Curiosity rover mission of the Mars Science Laboratory in search of clues whether the Red Planet was once hospitable to life.

Soviet Space
For the first time ever available in the West. Rocket & Space Corporation Energia: a complete pictorial history of the Soviet/Russian Space Program from 1946 to the present day all in full color. Available from our store.
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Viking patch
This embroidered mission patch celebrates NASA's Viking Project which reached the Red Planet in 1976.
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Apollo 7 DVD
For 11 days the crew of Apollo 7 fought colds while they put the Apollo spacecraft through a workout, establishing confidence in the machine what would lead directly to the bold decision to send Apollo 8 to the moon just 2 months later.
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Gemini 12
Gemini 12: The NASA Mission Reports covers the voyage of James Lovell and Buzz Aldrin that capped the Gemini program's efforts to prove the technologies and techniques that would be needed for the Apollo Moon landings. Includes CD-ROM.
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Apollo 11 special patch
Special collectors' patch marking the 35th anniversary of the historic Apollo 11 moon landing is now available.
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Inside Apollo mission control
An insider's view of how Apollo flight controllers operated and just what they faced when events were crucial.
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The ultimate Apollo 11 DVD
This exceptional chronicle of the historic Apollo 11 lunar landing mission features new digital transfers of film and television coverage unmatched by any other.
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Next ISS crew
Own a little piece of history with this official patch for the International Space Station's Expedition 11 crew. We'll ship yours today!
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Apollo patches
The Apollo Patch Collection: Includes all 12 Apollo mission patches plus the Apollo Program Patch. Save over 20% off the Individual price.
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