Astrophysicist Estimates Diameter Of The Universe
The diameter of the Universe has been estimated at 156 billion light years by astrophysicist Neil Cornish (Montanna State University). The results were published in Physical Review Letters last week.
The estimate was reached by estimating both the time that light has been traveling from the most distant galaxies we can see, and then factoring in the expansion of the space in between galaxies that has happened since the Big Bang.
How can the most distant galaxies be both 13.7 billion years old, and yet 156 billion light-years apart? Did they travel faster than light? Space.com asked Neil Cornish:
"The problem is that funny things happen in general relativity which appear to violate special relativity (nothing traveling faster than the speed of light and all that).
"Let's go back to Hubble's observation that distant galaxies appear to be moving away from us, and the more distant the galaxy, the faster it appears to move away. The constant of proportionality in that relationship is known as Hubble's constant.
"One seemingly paradoxical consequence of Hubble's observation is that galaxies sufficiently far away will be receding from us at a velocity faster than the speed of light. This distance is called the Hubble radius, and is commonly referred to as the horizon in analogy with a black hole horizon.
"In terms of special relativity, Hubble's law appears to be a paradox. But in general relativity we interpret the apparent recession as being due to space expanding (the old raisins in a rising fruit loaf analogy). The galaxies themselves are not moving through space (at least not very much), but the space itself is growing so they appear to be moving apart. There is nothing in special or general relativity to prevent this apparent velocity from exceeding the speed of light. No faster-than-light signals can be sent via this mechanism, and it does not lead to any paradoxes."
For more information, see Universe Measured: We're 156 Billion Light-Years Wide!; reference from KurzweilAI.net.
Scroll down for more stories in the same category. (Story submitted 5/25/2004)
Follow this kind of news @Technovelgy.
| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
you like to contribute a story tip?
Get the URL of the story, and the related sf author, and add
Comment/Join discussion ( 7 )
Related News Stories -
Is There A Subterranean Ocean?
'A vast, limitless expanse of water, the end of a lake if not of an ocean, spread before us, until it was lost in the distance.'- Jules Verne, 1864.
The Robotic Shopping Cart Of The Future
'...the machine would carry his bag in its soft plastic jaws and follow him as faithfully as a well-trained hound.'- John Brunner, 1975.
Arctic Resource Jackpot An Old Wish
By inducing climate change, new resources are revealed.
Marie Curie's Papers Still Radioactive
And the half-life of radium's most common isotope is 1,601 years.
Technovelgy (that's tech-novel-gee!)
is devoted to the creative science inventions and ideas of sf authors. Look for
the Invention Category that interests
you, the Glossary, the Invention
Timeline, or see what's New.
3D Skin Printer Helps Burn Victims
'Over her lacerated right shoulder he sprayed art-derm...'
Tesla Autopilot's 40 Percent Crash Reduction
''I hope all those other cars are on automatic,' he said anxiously.'
Pent-Up NASA Scientists Simulate Life On Mars
'That gives it complete isolation.'
China Now Has Robot Journalists
'A vast complex electronic organism buried deep in the ground, responsible to no one...'
Relationship-Practicing Robot From Turing Robot
'Streamlined, smooth-working, absolutely noiseless, breath-takingly realistic.'
Cormorant Flying Car
'The cab came floating down out of the sky...'
ElliQ Robot To Help Israel's Grandmas And Grandpas
'The robant and the tiny old woman entered the control room slowly...'
EU Debates Kill Switches For Robots
'I have a mechanism which our autofac on Mars builds as an... emergency safety...'
Scotland Set To Implement Basic Income
'Earned by just being born.'
Sales Robots More Persistent Than Humans
'Robot-salesmen were everywhere, gesturing,,, shrilling...'
AI Identifies Suicidal Behavior With 93 Percent Accuracy
'...He padded into the living room, and seated himself by the suitcase; he opened it, clicked switches, and turned on Dr. Smile.'
Razer Project Valerie Laptop Unfurls
'A paper thin polycarbon screen unfurled silently...'
Can Virtual Reality help People Cope With Pain?
Research is promising.
Dust Movement On The Moon, Saturn's Rings Solved
'...The dust normally on the surface picks up and keeps a charge.'
Largest Micro-Drone Swarm Release Successful
'... Programmed to hang in space in a hexagonal grid pattern.'
Robot Motion Planning 10K Times Faster
'The robot crab... fired a burst of light, then froze...'
More SF in the News Stories
More Beyond Technovelgy science news stories