Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cosmologically speaking, diamonds may actually be forever

26.04.2007
If you’ve ever wondered about the ultimate fate of the universe, Lawrence Krauss and Robert Scherrer have some good news - sort of.

In a paper published online on April 25 in the journal Physical Review D, the two physicists show that matter as we know it will remain as the universe expands at an ever-increasing clip. That is, the current status quo between matter and its alter ego, radiation, will continue as the newly discovered force of dark energy pushes the universe apart.

“Diamonds may actually be forever,” quips Krauss, professor of physics and astronomy at Case Western Reserve University (CWRU) who is spending the year at Vanderbilt. “One of the only positive things that has arisen from the dark-energy dominated universe is that matter gets to beat radiation forever.”

This viewpoint runs contrary to conventional wisdom among cosmologists. Today, there is more matter than radiation in the universe. But there were periods during the early universe that were dominated by radiation due to particle decays. The generally accepted view of the distant future has been that ordinary matter particles – protons and neutrons in particular – will gradually decay into radiation over trillions upon trillions of years, leaving a universe in which radiation once again dominates over matter; a universe lacking the material structures that are necessary for life.

It is only in the last decade that the existence of dark energy has been recognized. Before that Krauss and collaborators argued for its existence based on indirect evidence, but the first direct evidence came in 1998 when a major survey of exploding stars, called supernovae, revealed that the universe is apparently expanding at an increasing rate. Dark energy acts as a kind of anti-gravity that drives the expansion of the universe at large scales. Because it is associated with space itself, it is also called “vacuum energy.” A number of follow-up observations have supported the conclusion that dark energy accounts for about 70 percent of all the energy in the universe.

“The discovery of dark energy has changed everything, but it has changed the view of the future more than the past. It is among the worst of all possible futures for life,” says Krauss, who has spent the last few years exploring its implications. In an eternally expanding universe there is at least a chance that life could endure forever, but not in a universe dominated by vacuum energy, Krauss and CWRU collaborator Glenn Starkman have concluded.

As the universe expands, the most distant objects recede at the highest velocity. The faster that objects recede, the more that the light coming from them is “red-shifted” to longer wavelengths. When their recessional velocity reaches light speed, they disappear because they are traveling away faster than the light that they emit. According to Krauss and Starkman, the process of disappearance has already begun: There are objects that were visible when the universe was half its present age that are invisible now. However, the process won’t become really noticeable until the universe is about 100 billion years old. By ten trillion years, nothing but our local cluster of galaxies will be visible.

From the perspective of future civilizations, this process puts a finite limit on the amount of information and energy that will be available to maintain life. Assuming that consciousness is a physical phenomenon, this implies that life itself cannot be eternal, Krauss and Starkman argue.

“Our current study doesn’t change the process, but it does make it a little friendlier for matter and less friendly for radiation,” says Scherrer, professor of physics at Vanderbilt.

In their paper, Krauss and Scherrer analyzed all the ways that ordinary matter and dark matter could decay into radiation. (Dark matter is different from dark energy. It is an unknown form of matter that astronomers have only been able to detect by its gravitational effect on the ordinary matter in nearby galaxies.

At this point, the physicists have no idea whether it is stable or will ultimately decay like ordinary matter.) Given known constraints on these various decay processes, the two show that none of them can produce radiation densities that exceed the density of the remaining matter. This is counter-intuitive because, when matter turns into energy, it does so according to Einstein’s equation, E=mc2, and produces copious amounts of energy.

“The surprising thing is that radiation disappears as fast as it is created in a universe with dark energy,” says Krauss.

The reason for radiation’s vanishing act involves the expansion of space. Expanding space diminishes the density of radiant energy in two ways. The first is by increasing the separation between individual photons. The second is by reducing the amount of energy carried by individual photons. A photon’s energy is contained entirely in its electromagnetic field. The shorter its wavelength and the higher its frequency, the more energy it contains. As space itself expands, the wavelengths of all the photons within it lengthen and their frequency drops. This means that the amount energy that individual photons contain also decreases. Taken together, these two effects dramatically reduce the energy density of radiation.

Protons and neutrons, by contrast, only suffer from the separation effect. Most of the energy that they carry is bound up in their mass and is not affected by spatial expansion. In an accelerating universe, that is enough of an advantage to maintain matter’s dominance - forever.

The research was funded by grants from the National Science Foundation and the U.S. Department of Energy.

David Salisbury | Vanderbilt University
Further information:
http://www.vanderbilt.edu
http://www.vanderbilt.edu/exploration/stories/matterdom.html

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>