walking man

Estátua viva

Aphex Twin - Gwelly Mernans

Spot "Cinco razões para não usar preservativo"

Earth Song - Michael Jackson (legendado em português)

Espaço-tempo

Einstein was right! Nasa Fermi telescope uncovers proof of famous space-time theory

By Daily Mail Reporter
Last updated at 1:44 AM on 01st November 2009


Racing across the Universe for the last 7.3-billion-years, two highly charged particles have arrived at Nasa's Fermi Gamma-ray Space Telescope within a second of one another. Excited scientists believe this could be evidence of Einstein's space-time theory.

The photons were launched on their marathon during a short gamma-ray burst, an outpouring of radiation likely generated by the collision of two neutron stars, the densest known objects in the Universe.

One of the photons possessed a million times more energy that the other but they arrived at almost the same time.
photons

In this illustration, one photon (purple) carries a million times the energy of another (yellow). Some theorists predict travel delays for higher-energy photons. Yet Fermi data failed to show this effect

In Einstein's vision of a unified space-time all forms of electromagnetic radiation, from gamma rays through to X-rays, are thought to travel through the vacuum of space at the same speed, no matter how much energy they have.

But in some new theories of gravity, space-time is considered to have a 'shifting, frothy structure' when viewed at a scale trillions of times smaller than an electron.

These new models of the Universe say this 'foamy texture' would slow down the higher-energy photon relative to the lower energy one.

The Fermi Telescope results showed this did not happen as scientists believe the nine-tenths of a second gap, when spread over more than seven billion years, is too small to be significant.

Professor Peter Michelson from Stanford University said: 'This measurement eliminates any approach to a new theory of gravity that predicts a strong energy-dependent change in the speed of light.'

The principal investigator for Fermi's Large Area Telescope (LAT) concluded: 'To one part in 100 million billion, these two photons traveled at the same speed. Einstein still rules.'

Professor Michelson's team has published a paper on the findings in the online version of the journal Nature.


More...

* Earliest star blast helps astronomers peer back to dawn of time

Physicists have yearned for years to develop a unifying theory of how the universe works. But no one has been able to come up with one that brings all four of the fundamental forces in the universe into one tent.

The Standard Model of particle physics is considered to have succeeded in unifying three of the four. These are the 'strong force' that holds nuclei together inside atoms and the 'weak force' that is responsible for radioactive decay and electromagnetism.

However gravity has always been the odd man out in this model. Though a host of theories have been advanced, none has been shown successful.

Albert Einstein's theories of relativity also fail to unify the four forces but the latest evidence suggests he was nearer to the truth than many modern theories.

Read more: http://www.dailymail.co.uk/sciencetech/article-1223853/Nasa-Fermi-telescope-uncovers-proof-Einsteins-space-time-theory.html?ITO=1490#ixzz0VbzlkcQ0