WMAP Resolves the Universe - Those accuracy figures!

Comments and questions about the APOD on the main view screen.
cyent
Asternaut
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WMAP Resolves the Universe - Those accuracy figures!

Post by cyent » Sun Sep 25, 2005 10:08 pm

The universe is 13.7 billion years old (accurate to 1 percent),
expanding at the rate of 71 km/sec/Mpc (accurate to 5 percent),
Are they real? Are they absolute? Or merely the accuracy of this particular observation not including the errors in all the other observations on which they are built.

It seems utterly mind boggling. Quite the most amazing thing I have seen on APOD, which is quite the best source of amazing things on the 'net.

For example, if the expansion rate is uncertain to 5%, how can the age be certain to 1%?

And the composition figures? Any accuracy estimates on them?

I'm only qualified enough to look upon those accuracy figures with awe and amazement, but not enough to judge them right or wrong.
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S. Bilderback
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Post by S. Bilderback » Mon Sep 26, 2005 12:57 am

I'll probably receive negative feedback on this but those numbers aren't necessarily accurate to anything other than the perception of time in our little corner of the universe. There recently has been new galaxies found at a distance putting them at almost 12 billion years old but their measured properties say they are five to seven billion years old meaning parts of the universe are up to 19 billion years old, or, our best people don't know everything. New things are discovered every day, I wouldn't put my reputation on the line by setting a qualifier of 1% covering all observations.

makc
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Post by makc » Mon Sep 26, 2005 7:54 am

It goes like this: I've got a theory, but numeric values of constants are missing part, so I set up a device to measure them with 1% error max, in accordance to my theory. Would I happen to have different theory, I would build different device to measure different constant values, again with 1% error max.

cyent
Asternaut
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Joined: Thu Jun 16, 2005 8:38 pm

Post by cyent » Tue Sep 27, 2005 12:53 am

makc wrote:It goes like this: I've got a theory, but numeric values of constants are missing part, so I set up a device to measure them with 1% error max, in accordance to my theory. Would I happen to have different theory, I would build different device to measure different constant values, again with 1% error max.
Ok, after reading this and reading around I'm starting to get the picture. But still, Wow! At least it's a falsifiable theory with some amazingly tight (for this domain) estimates on the parameters.

Time to drop the old Joke about cosmologists only needing pencils, not even needing rubbers... :-)

It's still an impressive achievement, even if they prove the theory wrong tomorrow.

I'm still amazed and fascinated.
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Wayne
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Post by Wayne » Wed Sep 28, 2005 1:02 am

A cosmologist is often wrong, but never in doubt. It's a famous quote and it makes a cosmologist the opposite to a priest, who is never wrong but often in doubt.

Experimental value is limited by the theory in use. If I use Newtonian dynamics, my error margins for a falling object will be larger than if I were to use relativity, since relativity is a more exact theory. This isn't entirely a good example, but it's the best I can think of.

Ultimately it's the accuracy of equipment built according to those theories and experiments carried out using the theories. We will never get to 100% accuracy on any piece of equipment, as doing so would require the measurement of the infinitely large or the infinitely small.

(Note: "infinitely" here means "Immeasurably". In what terms do you measure the radius a quark, for example? Even a few thousand times larger, at the scale of a molecule, do you use the covalent radius or the Van der Waals radius?)

makc
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Post by makc » Wed Sep 28, 2005 6:09 am

does a quark have a radius?

S. Bilderback
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Post by S. Bilderback » Wed Sep 28, 2005 11:18 am

For the record, a quark actually measures 0.000000000000000001 meters.