How big is YOUR universe?

[Atrax robustus]

Astronomers size up the Universe
By Dr David Whitehouse
BBC News Online science editor

The Universe is at least 156 billion light-years wide, say astronomers.
The estimate comes from data obtained by a space probe that is examining the so-called Cosmic Background Radiation - often called the echo of the Big Bang.

The echo contains information of what the cosmos was like when it was young and how it might develop.

The cosmos is 13.7bn years old but the stretching of space with its expansion after the Big Bang means that simple distance measurements do not apply.

Stretched space

This age estimate comes from two independent lines of investigation - the age of stars and the expansion of the Universe.

This means that radiation reaching us from the earliest Universe has been travelling for more than 13 billion years.

But the assumption that flows from this - that the radius of the Universe is 13.7 billion light-years and that it is 27.4 billion light-years wide does not follow.

Astronomers realise the Universe is more complex. It has been expanding ever since the Big Bang when energy, space and time itself began.

According to Neil Cornish of Montana State University, US, and colleagues writing in the journal Physics Review Letters, the distance covered by the light in the early Universe gets increased by its overall expansion.

To get the picture try to imagine the Universe a million years after the Big Bang. Light travels for a year, covering one light-year. But at that time, the Universe was about a thousand times smaller than it is today meaning that one light-year has now become stretched to about a thousand light-years.

When this expansion is taken into account the Universe is bigger than it would appear to be.

Neither finite nor infinite

Because of this stretching, radiation from the early Universe cannot be said to have travelled 78 billion light-years.

What it means is that the starting point of a particle of light, a photon, reaching us today after travelling for 13.7 billion years is now 78 billion light-years away.


NASA'S WILKINSON PROBE
Launched to obtain full-sky images of 13 billion+ year-old temperature fluctuations in CMB
Temperature differences correspond to "seeds" that grew to become stars and galaxies
Data help answer questions about age and geometry of Universe


And that is the radius of the Universe. Confused?
The new estimate comes from analysing data obtained by the Wilkinson Microwave Anisotropy Probe (WMap) which has been studying the Cosmic Background Radiation which formed about 400,000 years after the Big Bang.

Subtle differences in the background radiation can tell astronomers the age of the Universe and other cosmological parameters.

One implication of the new analysis is to prove false the idea that one could, theoretically, look in one direction and eventually see the back of your head.

The researchers looked for evidence that multiple images of the same object could show up in different locations in space-time.

The predicted pattern in the CMB that would have shown the effect was not observed.

According to the researchers the latest work provides no evidence that the Universe is finite and no evidence that it is infinite either.

I said you might be confused.

http://news.bbc.co.uk/nol/shared/spl/hi/sci_nat/03/cmb/img/cmb_popup.jpg
About 300,000 years after Big Bang, matter and radiation "decoupled"
Matter went on to form stars and galaxies; radiation spread out and cooled
Radiation now shines in microwave portion of the electromagnetic spectrum - at a very cold -270.45 deg Celsius
By mapping tiniest temperature fluctuations (mottled colours above) in CMB, astronomers can "see" distribution of matter in early Universe



Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/3753115.stm

Published: 2004/05/28 10:21:04 GMT

© BBC MMIV
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Clear as mud.

I try to take an interest in these things, but sometimes I just get so perplexed!
:confused:

[Atrax robustus]

Telescope spies 'youngest' planet
Nasa's Spitzer telescope has found evidence around a distant star for a planet that may be less than one million years old.
The infrared space observatory studied five stars in the constellation Taurus, about 420 light-years away.

All had dusty discs around them in which new planets are presumed to be forming out of accreting material.

And for the star CoKu Tau 4, Spitzer saw a clearing in the disc which could have been swept clean by a new world.

Life's necessity

Nasa is excited by the latest findings from its $2bn space telescope launched last August.

It cannot see objects the size of planets directly, but its infrared detectors can penetrate the dusty clouds around very young stars probing the regions in which planets are forming.


Spitzer has now detected significant amounts of icy organic materials sprinkled throughout these "planetary construction zones".
These materials - icy dust particles coated with water, methanol and carbon dioxide - may help explain the origin of icy bodies like comets, the US space agency says.

Scientists believe such comets may have deposited on the primitive Earth water and many other chemicals that became the building blocks of life.

"These early results show Spitzer will dramatically expand our understanding of how stars and planets form," said Dr Michael Werner, Spitzer project scientist at Nasa's Jet Propulsion Laboratory in California.

Earth comparison

The Spitzer finding of a clear path in the CoKu Tau 4 disc - like a vacuum leaving a cleared trail on a dirty carpet, as Nasa described it - is intriguing.

Spitzer is able to reveal more about the structure of such gaps in stellar discs than has been previously possible.


Because CoKu Tau 4 is thought to be only about one million years old, the possible planet would be even younger. Compare this with the Earth which is thought to be more than 4.5 billion years old.
The CoKu Tau 4 planet must therefore be in the earliest stages of its formation and this will help astronomers understand the formation of planets such as our own.

Common process

Spitzer has also discovered two of the faintest and farthest planet-forming discs yet observed.

They surround two of more than 300 newborn stars seen in a dusty stellar nursery called RCW 49, which is about 13,700 light-years distant.

Astronomers believe that the formation of dusty discs around stars is a common phenomenon indicating that planets - which form from the disc - are widespread in the cosmos.

"By seeing what's behind the dust. Spitzer has shown us star and planet formation is a very active process in our galaxy," says Dr Ed Churchwell of the University of Wisconsin, US.


http://newsimg.bbc.co.uk/media/images/40206000/jpg/_40206225_planet_nasa_203.jpg
An impression of what it might be like in the CoKu Tau 4 system


http://newsimg.bbc.co.uk/media/images/40209000/gif/_40209185_circumstellar2_inf203.gif


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/3755617.stm


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Now thats pretty cool! :)

[Captain Bryan]

I would love to see the edge of the universe.

[eSJayBee]

about that article talking about the size of the univese: say what? :confused: ;) Not really my interest but a good read. Confusing, though.



And the young planet one: For some reason, the prospects of a new planet being found is sort of interesting even though I normally don't get into these kinda stuff. :)