 |
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 |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion ( 7 )
Related News Stories - (" Misc ")
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.
Current News
TytoCare Offers Futuristic Home Care
'Immediately an enormous apparatus fell on to her out of the ceiling...'
Powdered Regolith Propulsion
'... filling their great tanks with the finely divided dust which the ionic rockets would spit out in electrified jets.'
Ford's SafeCap, Opposite Of Niven and Barnes' Napcap
'In the napcap a client became an instant yoga master...'
Would You Get 'Chipped'? Michigan May Ban Employers
'Employees above a certain level were implanted with advanced microprocessors...'
Tesla Autopilot: What Does An Autonomous Car See When It Looks At The Road?
'Jeremiah is a sports-model to begin with and that kind is awfully hot-tempered.'
DNA Controls Swarms Of Molecular Robots
'They exist in loose swarms...'
Tether Asteroids To Save Us All
'If anything can glue the asteroids back into the planet they once were, magnology will do it.'
Blaux Your Personal Commuter Cooling Unit
A cooling unit had to be strapped to every commuter's back, by law.
3D Printed Damascus Steel Now Possible
'...lined with durite, that strange close-packed laboratory product.'
R9X Hellfire Missile With Long Blades Kills Queda Leader
'He was still roaring when the knife missile flicked past him...'
Would You Swallow An Origami Robot?
'Swallow it in an emergency--it goes down easily and works just as well inside as outside.'
Perhaps You Might Be Interested In Habitable Exoplanet Moon Real Estate
A long time ago in a galaxy far, far away...
Blurry Face Photos Made 60 Times Sharper
Perfect tool for blade runners.
SpaceX Will Build Floating Spaceports!
'...a single perfectly level platform, which rose so high above the water that it was not splashed by the waves.'
Fast Radio Bursts And Space Beacons For Interstellar Navigation
'Every beacon has a code signal as part of its radiation...'
Robot Garbage Trucks Visualized
'It was a bulky, shining cylinder over twenty metres long.'
