On 2009/03/28, at 2:07 PM, Bill Hooper wrote:
On Mar 24 , at 1:15 AM, Pat Naughtin wrote:
I want to write:
'The Universe is approximately 285 yottametres in diameter.'
Is this correct?
There probably IS NO firmly established measurement of estimate of
that distance. I googled diameter of the universe and found several
useful sites. One was this one (below) which I'd suggest starting
with, It contains 12 different estimates of the size of the
universe, all reduced to a value in billions of light years for ease
of comparison.
The site is: http://hypertextbook.com/facts/2002/CarmenBissessar.shtml
It gives most values of 20 to 30 billion light years, but some are
considerably larger and a few smaller. Using the 20 to 30 billion
l.y. figures I get the following:
A light year (l.y.) is 9.46 x 10^15 m.
(Ref. Any decent physics text book like the one in front of me).)
20 billion l.y. is equal to 20 x 10^9 l.y. which,
by multiplying the above two figures, gives us
(20 x 10^9 l.y.) x (9.46 x 10^15 m/l.y.) or
20 billion l.y. = 190 x 10^24 m
or, finally:
20 billion l.y. = 190 Ym
Similarly, 30 billion l.y. = 280 Ym
I hope this gives you an answer you can use. Just be aware that it
is really unknown and all such sizes are estimates based on some
widely different criteria.
Regards,
Bill Hooper
Fernandina Beach, Florida, USA
Dear Bill,
Many thanks for this reference — and for your calculations. I shall
proceed with confidence; an estimate of 'about 250 yottametres' looks
OK for my purposes. The purpose of the question was simply to
demonstrate that the metric system in its current form as the
International System of Units (SI) is able to be used for measurements
from the largest things we know to the smallest. In short, that
Condorcet's 1790s line, that the metric system is 'For all time, for
all people' still holds true.
As a matter of interest, I took the data from the web page your
provided and added an extra column for the extent of the Universe in
yottametres. Here is the table with the additional column.
Bibliographic Entry
Result (with surrounding text)
Light years
yottametres
Blair, William. Size Scales in Astronomy. November 2001.
"That this distance is deemed almost inconsequential compared with the
most distant objects known in the universe, which are roughly 10
billion light years away."
20 billion light years
190 Ym
The Scale of Things. The Internet Stellar Database.
"And the distance to the edge of the known universe is around 100,000
million million million kilometers."
20 billion light years
190 Ym
God the Creator. goodnewsdaily.org. Number692. 30 April 30 2002.
"Latest estimates by astronomers tell us that the universe is 30 or 40
billion light years in diameter. In layman's terms, that means that it
would take light (which travels at the speed of light J) 40 000 000
000 years to cross from one side of the universe to the other!"
30–40 billion light years
280 Ym
to
380 Ym
The Size and Shape of the Universe. infoplease.com.
"At present the universe is believed to be at least 10 billion light-
years in diameter."
10 billion light years
95 Ym
Butterworth, Paul. Measuring the Size of the Universe. Imagine the
Universe! NASA.
"The simple answer is that the observable Universe is about 10 billion
light years in radius. That number is obtained by multiplying how old
we think the Universe is by the speed of light."
20 billion light years
190 Ym
Macmillan Encyclopedia of Physics. New York: Macmillan, 1996.
"The observable universe extends out to approximatly 10 billion light
years away."
20 billion light years
190 Ym
Milton, Simon. The Oxford Book of Astronomy. New York: Oxford, 1998.
"Diameter of Universe 10^26 (miles)"
16 billion light years
150 Ym
Asimov, Isaac. The Collapsing Universe. New York: Walker, 1977.
"The nearest qusars are 3 billion light years from earth, while the
most remote ones may be 6 times as far."
36 billion light years
340 Ym
The Really Big Numbers Page. (from Chalk Up Another One by Sidney
Harris).
"Diameter of the Universe (1026)" [Author did not include a unit.]
?
?
Size Scales in Astronomy. William P. Blair, Johns Hopkins University.
Version 1.0, January 1996.
"On this scale, the 'edge' of the Universe, defined as the most
distance known quasars some 10 billion light years."
20 billion light years
190 Ym
Neil J. Cornish, David N. Spergel, Glenn D. Starkman, Eiichiro
Komatsu. Constraining the Topology of the Universe. arXiv,
astrophysics, 0310233 (8 October 2003).
"For a wide class of models, the non-detection rules out the
possibility that we live in a universe with topology scale smaller
than 24 Gpc."
156 billion light years
1 500 Ym
Britt, Robert Roy. Universe Measured: We're 156 Billion Light-years
Wide! space.com 24 May 2004.
"All the pieces add up to 78 billion-light-years. The light has not
traveled that far, but 'the starting point of a photon reaching us
today after travelling for 13.7 billion years is now 78 billion light-
years away,' Cornish said. That would be the radius of the universe,
and twice that -- 156 billion light-years -- is the diameter. That's
based on a view going 90 percent of the way back in time, so it might
be slightly larger."
156 billion light years
1 500 Ym
Cheers and thanks again for your help,
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
their businesses. Pat provides services and resources for many
different trades, crafts, and professions for commercial, industrial
and government metrication leaders in Asia, Europe, and in the USA.
Pat's clients include the Australian Government, Google, NASA, NIST,
and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com
for more metrication information, contact Pat at [email protected]
or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter
to subscribe.
