Dark Matter and Dark energy


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Profile Thierry Van Driessche
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Message 13218 - Posted: 28 Jul 2004, 19:56:43 UTC
Last modified: 26 Aug 2004, 19:13:12 UTC

14:34 28 July 04

NewScientist.com news service

Is the mysterious dark energy that drives the expansion of the cosmos subtly sabotaging physics experiments right here on Earth? A new theory suggests there might be an intriguing link between dark energy and tiny particles called neutrinos, and this could account for puzzling results from various neutrino experiments around the world.

In 1998, astronomers were surprised to discover that the expansion of the universe is accelerating thanks to some kind of “dark energy” that pushes space apart. There are several theories about what the dark energy might be, but currently they are all very difficult or impossible to test.

In 2003, however, Rob Fardon, Ann Nelson and Neal Weiner at the University of Washington in Seattle suggested a possible connection between the dark energy and ordinary particles called neutrinos.

Neutrinos are nature’s lightest particles of matter, and were churned out in vast quantities just after the universe formed. They are also highly elusive, travelling at enormous speeds and can easily fly straight through planets and stars.

Estimates of the energy density in all these whizzing neutrinos are sketchy. But it seems to be roughly similar to the dark energy density at the present time, and the Washington team suggests that is not just a coincidence. They think these energy densities have been similar throughout the history of the universe, because the dark energy consists of an energy field that has a complex interplay with neutrinos.

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Message 17910 - Posted: 26 Aug 2004, 19:21:10 UTC
Last modified: 26 Aug 2004, 19:22:12 UTC

From Spacedaily

The Role Of Particle Physics In A New Universe

A string of recent discoveries in astronomy has left scientists with an unsettling realization: The stuff we know and understand makes up less than 5 percent of the universe. The rest has to be yet-unknown forms of "dark matter" and "dark energy."
At a time of momentous changes in our basic understanding of the universe, a new document outlines the essential role of particle physics in deciphering the laws of nature that govern dark matter, dark energy and more.

Conceived to make the science as accessible as possible, the Quantum Universe report focuses on nine fundamental questions in response to a request by two major research funding agencies, the US Department of Energy and the National Science Foundation.

The report was prepared by a task force chaired by Persis Drell, director of research at the Stanford Linear Accelerator Center (SLAC).

The funding agencies asked their joint High Energy Physics Advisory Panel to appoint the task force and to charge it with explaining what particle physics can do, and what facilities it needs, to answer "the truly exciting scientific questions of this century."

The 58-page report, published in June, argues that answering such fundamental questions requires new knowledge from particle physics. "Quantum Universe makes it clear: These new discoveries are our problem," Drell said.

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An interesting document about following questions
1. Are there undiscovered principles of nature: new symmetries, new physical laws?
2. How can we solve the mystery of dark energy?
3. Are there extra dimensions of space?
4. Do all forces become one?
5. Why are there so many kinds of particles?
6. What is dark matter? How can we make it in the laboratory?
7. What are neutrinos telling us?
8. How did the universe come to be?
9. What happened to the antimatter?

can be downloaded here.

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Message 20504 - Posted: 31 Aug 2004, 18:39:34 UTC
Last modified: 31 Aug 2004, 18:39:52 UTC

From Space.com

Getting a Grip on Antimatter
By Michael Schirber
Staff Writer
posted: 31 August 2004
06:35 am ET


Research into what separates matter from antimatter is accelerating in particle physics experiments around the world. Scientists are hoping the difference will help explain why you, me and all the things around us are made of matter instead of its opposite.



Shortly after the Big Bang theoretically kicked off everything, the universe was a hot soup of equal parts matter and antimatter, scientists say. Why the former came to dominate is a question that physicists have yet to answer fully.

Recent results from the BaBar experiment in California have confirmed one departure between the two substances, but to solve the puzzle more deviations will have to be found.

"This was a very important step on the road to understanding the matter-antimatter asymmetry," said David MacFarlane, a physicist with the BaBar group. "This asymmetry is one of the fundamental questions of cosmology."

With equal mass but opposite electric charge, there are anti-particles that correspond to the proton, the electron, and the whole zoo of fundamental particles that physicists have so far catalogued.

Strange as they sound, these particles do exist, and they can be created. They just don't last long. If the existential partners come together, they completely annihilate each other

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