Astronomically Large Lenses Measure the Age and Size of the Universe

[n2doc]

ScienceDaily (Mar. 1, 2010) — Using entire galaxies as lenses to look at other galaxies, researchers have a newly precise way to measure the size and age of the universe and how rapidly it is expanding, on par with other techniques. The measurement determines a value for the Hubble constant, which indicates the size of the universe, and confirms the age of the universe as 13.75 billion years old, within 170 million years. The results also confirm the strength of dark energy, responsible for accelerating the expansion of the universe.

When a large nearby object, such as a galaxy, blocks a distant object, such as another galaxy, the light can detour around the blockage. But instead of taking a single path, light can bend around the object in one of two, or four different routes, thus doubling or quadrupling the amount of information scientists receive. As the brightness of the background galaxy nucleus fluctuates, physicists can measure the ebb and flow of light from the four distinct paths, such as in the B1608+656 system imaged above. (Credit: Image courtesy Sherry Suyu of the Argelander Institut für Astronomie in Bonn, Germany)

These results, by researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at the US Department of Energy's SLAC National Accelerator Laboratory and Stanford University, the University of Bonn, and other institutions in the United States and Germany, is published in the March 1 issue of The Astrophysical Journal. The researchers used data collected by the NASA/ESA Hubble Space Telescope, and showed the improved precision they provide in combination with the Wilkinson Microwave Anisotropy Probe (WMAP).

The team used a technique called gravitational lensing to measure the distances light traveled from a bright, active galaxy to the earth along different paths. By understanding the time it took to travel along each path and the effective speeds involved, researchers could infer not just how far away the galaxy lies but also the overall scale of the universe and some details of its expansion.
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http://www.sciencedaily.com/releases/2010/03/100301122334.htm

[damyank913]

1. I don't understand...

If nothing travels faster than light; how can we be where we are observing the light that was created 13.75 billion years ago? Would'nt the light have passed this point millenia ago?

[AlecBGreen]

3. see my post below

meant to reply to yr question, replied to OP instead

[AlecBGreen]

2. speed = distance / time

if you know two of the three, you can calculate the unknown. We know the speed of light and we know how far away the galaxies are, so we can calculate how long the light has taken to reach us.

[damyank913]

4. Here's my dilemma...

We'll use the above example in the post. If this light is 13.75 billion years old then it's safe to say that it was created pretty close to the Bang, right?

The universe is expanding but not at the speed of light.

Nothing that we know of can travel faster than light.

If we are not traveling faster than light; how can we be here (where-ever here is) to observe something that is traveling light-speed and came into existance before we did.

My intuition tells me that the thing traveling faster would have passed the slower thing eons ago.

I'm sure there's an explanation but I find this very puzzling.

[AlecBGreen]

5. check this out

http://curious.astro.cornell.edu/question.php?number=575

long story short, the universe is expanding faster than the speed of light and there are galaxies moving away from each other at speeds faster than light. I know its counterintuitive (nothing goes faster than light, right?) but I think its because the very fabric of space-time is stretching and we, embedded in it, are being taken along for a ride.

[damyank913]

6. Thank you-that helped alot.

[Motown_Johnny]

8. Hmmm.....

I have no doubt that the universe may be expanding faster than the speed of light. The math clearly points out this possibility and I accept it without question.

I am not sure that this is the correct answer to the question posted.


If the space between the observer and the source of the 13.75 billion year old light were expanding at a rate equal to or faster than C then the light would never reach the observer.



I may be wrong but I have always thought of it this way.




Picture someone with a very bright flashlight on a dark evening. This person is some distance from you and is pointing the light straight up in the air. You can't see the bulb (source of the light) but you can see the beam extending out into the open sky.


I have always considered the light that we observe from such a great distance as more of a "refraction" of the light source and not the source itself.


Maybe I am off base, I never gave it that much thought.

Please correct me if I am wrong, I would love to lower my level of ignorance on this subject.

[RagAss]

7. Because this is the Big Bang.