PDA

View Full Version : Astronomy, astrophysics question



cjolley
8th August 2006, 07:41
This is an article about a new way to calculate astronomic distances that may change the accepted Hubble Constant by 15%.

http://www.cnn.com/2006/TECH/space/08/08/universe.age/index.html

This is what struck me:


...
Scientists now estimate the universe to be about 13.7 billion years old (a figure that has seemed firm since 2003, based on measurements of radiation leftover from the Big Bang) and about 156 billion light-years wide.

The new finding implies that the universe is instead about 15.8 billion years old and about 180 billion light-years wide.

...




How could the universe be ~15 billion years old, but ~150 billion light years wide?
Doesn't that imply that the average rate of expansion is an order of magnitude greater than the speed of light?

Admittedly my detailed astrophysics knowledge dates from 1975, but on the face of it this sounds impossible.
Anyone know what gives?

Nowhere
8th August 2006, 18:07
Yes, the rate of expansion "is" (somehow...) order of magnitude greater than the speed of light. No, this doesn't violate Einstein's physics. Simply because the space itself expands.

KRSESQ
8th August 2006, 20:06
According to current theory, the universe reached 90% of its current size before Einstein kicked in, in just the first few hundred thousand years of its existence.

http://en.wikipedia.org/wiki/Big_Bang

Kevin

Dr Mordrid
8th August 2006, 20:52
WMAP = Wilkinson Microwave Anisotropy Probe, a 2001 probe to ameasure the distribution of the cosmic background radiation ( http://en.wikipedia.org/wiki/WMAP ) and thereby get a read on the conditions after the 'big bang'.

http://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/CMB_Timeline300.jpg/800px-CMB_Timeline300.jpg

Mehen
8th August 2006, 21:03
What is to say there are not multiple "universes?" Brings you back to that question you would always ask as a kid - how can space never end? and if it does end, what is beyond that - wouldn't it just be more space? And then if so - why not more "universes" in it? I think they should redefine universe.

Dr Mordrid
8th August 2006, 23:16
According to M-Theory (M variously = Magic, Membrane ['brane for short] or Matrix) there is a multitude of universes, a 'multiverse', contained in 11 dimensions: 10 spatial + time.

NOVA's 'Elegant Universe' online (3 hrs) does a fair job of putting it into English;

http://www.pbs.org/wgbh/nova/elegant/program.html (small frame QT/RM segments)

http://www.pbs.org/wgbh/nova/elegant/program_d.html (full screen QT/RM segments)

Check out the parallel universes segment (5 min)

KRSESQ
9th August 2006, 10:18
It's a donut! Astrophysicists are expecting or trying to explain why the universe isn't acting like a spherical bubble by using Dark Matter, which has never been observed.

The big bang occurred at the center of the donut and flat space is following the surface of the donut. Eventually it will travel completely around and collapse again.

http://list.terc.edu/pipermail/maine_science/2003-March/003903.html

Kevin

Nowhere
10th August 2006, 15:36
What is to say there are not multiple "universes?" Brings you back to that question you would always ask as a kid - how can space never end? and if it does end, what is beyond that - wouldn't it just be more space? And then if so - why not more "universes" in it? I think they should redefine universe.

It's a bit pointless asking what's beyond...you can't get there anyway, and also no information (and I mean - not in practical sense, but in theoretical physics sense)

VJ
11th August 2006, 06:09
It's a donut!

In the Simpsons episode with Stephen Hawking, there is moment where Hawking is at Moe's bar with Homer, and he states: "Homer, I may have to steal your idea of a donut-shaped universe".
:D

Jörg

Dr Mordrid
11th August 2006, 11:19
It's a donut! Dodecahedron?

http://news.nationalgeographic.com/news/2003/10/1008_031008_finiteuniverse.html

ESA's Max Planck probe should give cosmic background radiation data with enough resolution to say which shape the universe really is. Planck launches Q1 next year if all goes well;

http://www.rssd.esa.int/index.php?project=Planck