27
February 2003
String theory: Small is invisible
String theory is an all-embracing theory unifying the feeble force of gravity with the other forces of nature described by the Standard Model of particle physics. It states that point-like elementary particles are in fact tiny, string-like entities, and calls for six extra dimensions beyond the three we inhabit. We can't see them, theorists argue, because they are curled up into small spaces. But gravity derives from the properties of space-time itself, in however many dimensions it exists. So the largest of these invisible compact dimensions may have a detectable effect on gravity at small but measurable distances. Several experiments are under way to test this prediction, and the group from Boulder, Colorado, now reports final results. No new force was observed at distances of ~100 μm, putting a upper limit on the exotic and still hypothetical 'dilaton' and 'radion' forces.
Upper limits to submillimetre-range forces from extra
space-time dimensions
JOSHUA C. LONG, HILTON W.
CHAN, ALLISON B. CHURNSIDE, ERIC A. GULBIS, MICHAEL C. M. VARNEY & JOHN C.
PRICE
Nature 421, 922–925 (2003); doi:10.1038/nature01432
| First Paragraph
| Full Text (HTML
/ PDF) |
Gravity: The weight of expectation
C.
D. HOYLE
Newton devised his universal law of gravitation for planets, but
does it work at small scales? A search for a deviation from the expected behaviour
could provide the first evidence in support of string theory.
Nature
421, 899–900 (2003); doi:10.1038/421899a
| Full
Text (HTML / PDF) |
