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.
Cattle Avoidance Feature In Indian Autonomous Cars
'The driver went about the business of gently slipping the teflon-coated metal scoop beneath the first animal...'
Project KOVR Fashion Protection From Infosphere
'... the entire shroudlike membrane took on whatever physical characteristics were projected at any nanosecond.'
Twist Bioscience High Density Digital Data On DNA
'They tied the memory to the bloodline and that was their record!'
'We're Not Creating A Terminator' Say Russians About Gun-Wielding Robot Fedor
Nobody is thinking about the Terminator. Westworld, maybe.
Vantablack Now IMMEASURABLY Black
'a black coating now thatís ninety-nine percent absorptive...'
Mercedes-Benz Autonomous Taxi Fleet In 3 Years
'... the taxi utilized sophisticated electronic sensors to perceive its surroundings.'
Is 'The Pulsar Positioning System' Evidence For SETI?
'For a hyperspace jump, you need at least four beacons for an accurate fix.'
Someday, You Might Like VR Enough To Move In
'That barrier was going to melt away someday soon. The transhumanists had promised...'
Humans Use Mental Power For Turtle Slavery
Now we need to start looking for animals with fingers...
Solar-Powered Moisture Vaporator
'The atmosphere yielded its moisture with reluctance.'
DxtER! Tricorder Prize Won By Final Frontier Medical Devices
We've been waiting a long time for this, Star Trek fans.
President Trump's Wall As Otra Nation Hyperloop
'...an hollow tube must be constructed the whole distance... as to admit a four wheeled carriage...'
Pickup Lines From Artificial Intelligences
'They hate us, you know... The humans. They'll stop at nothing.'
Pooper Scooper Drone Robot Watchdog 1
'Robots pick up the garbage and junk...'
Cassie Robot Brings AT-ST Walker To Life
There's even a log test!
Hundreds Of Robot Lawnmowers Invade Texas Town
'The mower reached the edge of the lawn, clucked to itself...'
More SF in the News Stories
More Beyond Technovelgy science news stories