The Case for Fewer Dimensions

[n2doc]

At small scales, gravity seems to blow up—but not if space becomes 1-D.
BY GEORGE MUSSER

The adventures of the classic science-fiction novel Flatland by Edwin Abbott have sprung to life. The novel is narrated by a two-dimensional creature who calls himself “A Square,” who learns he has been embedded in a three-dimensional realm called Spaceland without knowing it. Like Mr. Square, physicists over the past century have begun to consider whether our world may be just a slice of a four- or even 10-dimensional expanse. If we could ascend into that higher domain, we would free ourselves from the straitjacket of ordinary space. We could bend our arm through an extra dimension to reach into a locked safe, or see the insides of a human body laid out before us. And we might finally apprehend the deep unity of nature.

But in recent years the dimensional saga has taken a curious twist: Space may not have more dimensions than we perceive around us, but fewer.

The dimensional constriction is wrapped around a problem with gravity, one of the four basic forces of nature. The gravitational attraction between two bodies gets stronger as the bodies get closer. That’s also true for other forces, like the electromagnetic and the weak force. But unlike those forces, gravity undergoes an additional strengthening on small scales. Its attractive force depends on the bodies’ masses or, equivalently, energy, and the uncertainty principle of quantum physics leads to a minimum in the amount of that energy. When the bodies are close enough to each other, that minimum begins to increase in inverse proportion to distance, causing them to attract with redoubled intensity. The other forces of nature also undergo a quantum strengthening or weakening, but to a much lesser degree. As a result, gravity, which is a pushover on everyday scales, catches up with the other forces and becomes their equal at a sub-sub-subatomic distance known as the Planck scale (around a few trillionths of a trillionth of a trillionth of a meter).

more
http://nautil.us/issue/29/scaling/the-case-for-fewer-dimensions

[roguevalley]

1. keep the science coming, dear hearts. I write science fiction. :D:D:D

[lastlib]

2. Thinking outside the box is so 20th-century.......

In the 21st century, you've got to think outside the tesseract.



(good luck with that.........!)

[phantom power]

3. "By the volume measure, space is 3-D, but by the behavior of random motion, it is 1-D"

And even when space seems reassuringly 3-D, it belies that appearance. The researchers imagined setting out on a meandering stroll, taking each step in a random direction, much as a gas molecule will do while caroming around a volume. In 3-D space, if you double the length of your journey, your chance of returning to your starting point should drop by the square root of eight. Yet the simulations found a slower decline near the Planck scale, as if there were less space to get lost in. That’s a telltale sign of fewer dimensions.

By the volume measure, space is 3-D, but by the behavior of random motion, it is 1-D, or even a fractional dimension. This discrepancy is a signal not only that space gets less roomy, but that its very nature changes as gravity begins to show its quantum aspects. “When you don’t have a normal manifold, there are typically many different definitions of ‘dimension,’ ” says Steve Carlip at the University of California, Davis.