Sentences with phrase «critical density»

Diana Al - Hadid, Edge of Critical Density, 2009.

Independently, while puzzling out other astronomical mysteries, they arrived at the same tantalizing predication that the universe was exactly balanced at critical density, the knife's edge.

In the simplest cosmological model, critical density just means that the inward pull of gravity is exactly strong enough to halt the outward expansion of the universe.)

Cosmologists measure the density of the universe against a number known as critical density — the amount of mass needed to cancel out the curvature of space.

Data from NASA's Wilkinson Microwave Anisotropy Probe, or WMAP, provide compelling evidence that the cosmos has the full critical density.

Adding up the inferred gravitational effects in galaxies, galaxy clusters, and large - scale structures implies that the total amount of matter in the universe, including dark matter, comes to about 30 percent of critical density.

Crucially, the math showed that ironing out temperature wrinkles in the cosmos would also leave the universe at critical density — delicately balanced between continuous growth and eventual collapse to a Big Crunch.

A Big Bang model in which there was just enough matter to equal the critical density to account for a flat universe would have provided that.

But the cloud would never reach that critical density without some way of cooling down, thereby reducing the pressure of the gas.

But so far, astronomers had discovered enough matter to make up only 30 percent of this critical density.

In trying to save the theory of inflation, which predicts that the universe is flat, we suggested that the gap between the critical density and the actual amount of matter is filled with something whose gravity is repulsive — something similar to what Einstein dubbed the cosmological constant, though in a new guise.

We now know the shape of the universe (flat) and the average density of matter and energy (critical density), and yet we don't know what will happen.

If the density is poised precisely between those extremes, at what is called the critical density, space would be uncurved — flat — and the slowing would continue forever.

When more hydrogen settles onto the star and heaps up to a critical density, another explosion occurs, releasing another burst of X-rays, and so on.

Last February, Charles Bennett of NASA's Goddard Space Flight Center announced the result: The overall geometry of the universe is flat, meaning the amount of mass and energy exactly matches the critical density.

The main conclusion of the JQI work is that the critical density is greater than the threshold density, so that there is a «sweet spot» for further development of a Ps gamma - ray laser.

Schwarzschild's results showed that, at some critical density, the star's gravity would become so strong that it would swallow everything — matter, light, even space and time — within a specific radius.

Using first - principles quantum theory, the JQI team has explored the time evolution of a Ps BEC containing various mixtures of spin - 0 and spin - 1 Ps atoms, and has found that there is a critical density of Ps, above which collision processes quickly destroy the internal coherence of the gas.

The same thing held our species back, until the population reached a critical density, unleashing the power of culture — at which point there was no stopping us.

The wikipedia reference above explains how the energy density of the universe was almost exactly equal to the critical density during the entire expansion and departed from it by less than one part in 1062.

By having the density be the critical density, the sum of the kinetic and potential energies would be exactly zero.

«The early universe must have had a density even closer to the critical density [rc], departing from it by one part in 1062 or less.»

Gravity will ultimately determine the fate of the expansion, and gravity is dependent upon the mass of the universe; specifically, there is a critical density of mass in the universe of 10 - 29 g / cm3 (equivalent to a few hydrogen atoms in a phone booth) that determines what might happen.

Diana Al - Hadid, Edge of Critical Density (opposite side), 2009.

Image: Diana Al Hadid, Edge of Critical Density, 2009, Courtesy of the artist and Marianne Boesky Gallery, New York, Photo by Peter Foe.