The Shadow of Dark energy

In summary: So dark energy is real, it's something not attracted to gravity, it's like a force, and it's like a tiny mass concentration.
  • #1
502
1
Well, apparently we have now found new and more direct evidence for the existence of the so called 'dark energy.' I find it quite remarkable.

http://www.space.com/scienceastronomy/dark_energy_030805.html [Broken]
 
Last edited by a moderator:
Astronomy news on Phys.org
  • #2
Originally posted by Brad_Ad23
Well, apparently we have now found new and more direct evidence for the existence of the so called 'dark energy.' I find it quite remarkable.

http://www.space.com/scienceastronomy/dark_energy_030805.html [Broken]

Quite remarkable to say the least

the result was announced July 19 by the Sloan Digital Sky Survey
(SDSS), here is their release:
http://www.sdss.org/news/releases/20030721.darkenergy.html

It explains the effect more thoroughly than the space.com article.

Passage thru a deep gravity well can give a photon energy if
the well gets shallower (due to dark energy expansiveness) while the photon is passing thru. Or at any rate that's what I could gather from the SDSS release.

glad you found this!
 
Last edited by a moderator:
  • #3


Here is a quote from theJuly 19 by the Sloan Digital Sky Survey
http://www.sdss.org/news/releases/20030721.darkenergy.html
--------

SDSS collaborator [Andrew] Connolly said if the depth of the gravitational well decreases while the photon travels through it then the photon would exit with slightly more energy. "If this were true then we would expect to see that the cosmic microwave background temperature is slightly hotter in regions with more galaxies. This is exactly what we found."

[Albert] Stebbins added that the net energy change expected from a single concentration of mass is less than one part in a million and researchers had to look at a large number of galaxies before they could expect to see the effect. He said that the results confirm that dark energy exists in relatively small mass concentrations: only 100 million light years across where the previously observed effects dark energy were on a scale of 10 billion light years across. A unique aspect of the SDSS data is its ability to accurately measure the distances to all galaxies from photographic analysis of their photometric redshifts. "Therefore, we can watch the imprint of this effect on the CMB grow as a function of the age of the universe," Connolly said. "Eventually we might be able to determine the nature of the dark energy from measurements like these, though that is a bit in the future."

"To make the conclusion that dark energy exists we only have to assume that the universe is not curved. After the Wilkinson Microwave Anisotropy Probe results came in (in February, 2003), that's a well-accepted assumption," [Ryan] Scranton explained. "This is extremely exciting. We didn't know if we could get a signal so we spent a lot of time testing the data against contamination from our galaxy or other sources. Having the results come out as strongly as they did was extremely satisfying."

The discoveries were made in 3,400 square degrees of the sky surveyed by the SDSS.

"This combination of space-based microwave and ground-based optical data gave us this new window into the properties of dark energy," said David Spergel, a Princeton University cosmologist and a member of the WMAP science team. "By combining WMAP and SDSS data, Scranton and his collaborators have shown that dark energy, whatever it is, is something that is not attracted by gravity even on the large scales probed by the Sloan Digital Sky Survey.

--------

In case anyone wants to see a preprint of their technical article:
http://arxiv.org/astro-ph/0307335 [Broken]
"Physical Evidence of Dark Energy" Scranton et al.

Ryan Scranton quoted here is team leader of the project. A photon gains energy by passing thru a gravity well while the well is getting shallower according to what is called the "Integrated Sachs-Wolfe" effect. It gains energy going down into the well and then does not have to give up all of it while coming out, so it has some left. Which the dudes measured.
 
Last edited by a moderator:

1. What is dark energy?

Dark energy is a hypothetical form of energy that is believed to make up about 70% of the universe. It is thought to be responsible for the accelerating expansion of the universe.

2. How was dark energy discovered?

Dark energy was first hypothesized by Albert Einstein in his theory of general relativity. It was later confirmed by observations of distant supernovae in the late 1990s, which showed that the universe is expanding at an accelerating rate.

3. What is the role of dark energy in the universe?

The role of dark energy in the universe is to counteract the force of gravity and cause the expansion of the universe to accelerate. It is also thought to play a role in the large-scale structure of the universe, influencing the distribution of galaxies.

4. How does dark energy differ from dark matter?

Dark energy and dark matter are two different concepts. Dark energy is a type of energy that is believed to be responsible for the accelerating expansion of the universe, while dark matter is a form of matter that does not interact with light and is thought to make up about 27% of the universe.

5. Can dark energy be harnessed for use in technology?

At this time, there is no known way to harness or use dark energy for technology. It is a still a theoretical concept that requires further research and understanding before it can potentially be utilized in any practical applications.

Suggested for: The Shadow of Dark energy

Replies
6
Views
428
Replies
5
Views
642
Replies
1
Views
834
Replies
13
Views
2K
Replies
14
Views
1K
Replies
1
Views
991
Back
Top