how to convert hubbles constant into SI units?

dodster

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Jun 1, 2004, 6:30:38 AM6/1/04

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how to convert hubbles constant from conventional units into SI units?
kms(-1) Mpc(-1) to SI = s(-1)
please help send reply to dodste...@yahoo.com
thanks

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Michael Varney

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Jun 1, 2004, 7:23:21 AM6/1/04

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"dodster" <dodste...@yahoo-dot-com.no-spam.invalid> wrote in message
news:40bc5...@127.0.0.1...

> how to convert hubbles constant from conventional units into SI units?
> kms(-1) Mpc(-1) to SI = s(-1)
> please help send reply to dodste...@yahoo.com
> thanks

This is a simple conversion that should be easy to do.

km/s 1/Mps is a speed/distance

This means that it is quite obvious that Hubble's constant has dimensions of
inverse seconds.

km = 1000 m

Mps is a mega parsec.

A parsec is defined in:
http://scienceworld.wolfram.com/astronomy/Parsec.html

with an approximation to meters as:

1 parsec = 3.086E16 m

And the prefix mega is 1E6

so 1 Mpc = 3.086E22 m

So, km/(s Mpc) ~ 3.24E20 1/sec

Hubble's constant, given in:

http://scienceworld.wolfram.com/physics/HubbleConstant.html

H0 = 81(+-8) km/(s Mpc) ~ 2.6E-18 1/s in SI

You really should know this. I believe they cover such unit conversions in
elementary school.

However, such a conversion is rather useless in its reduced SI form.

Finally;

www.google.com "how to use google"

jmfb...@aol.com

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Jun 1, 2004, 6:58:27 AM6/1/04

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In article <TEZuc.1$4Z....@news.uswest.net>,

But do they teach exponential arithmetic?

>
>However, such a conversion is rather useless in its reduced SI form.

Can calculators handle it? [impish emoticon laying a fish line
across the screen]

>
>Finally;
>
>www.google.com "how to use google"

I got problems with this suggestion. But then I'm having
all kinds of other problems from banks insisting that go
on-line, too.

/BAH

Subtract a hundred and four for e-mail.

Michael Varney

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Jun 1, 2004, 8:09:18 AM6/1/04

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<jmfb...@aol.com> wrote in message
news:40bc705f$0$3119$61fe...@news.rcn.com...

I don't know... I never went. :-)

Sam Wormley

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Jun 1, 2004, 9:25:26 AM6/1/04

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dodster wrote:
>
> how to convert hubbles constant from conventional units into SI units?
> kms(-1) Mpc(-1) to SI = s(-1)

See: http://www.google.com/search?q=71+km%2Fs%2F+10%5E6+parsec

Bjoern Feuerbacher

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Jun 1, 2004, 12:21:29 PM6/1/04

to

I think a possible use might be to get an order-of-magnitude estimate
for the age of the universe by simply calculating 1/H. However, one
should additionally convert the result then from seconds to years. ;-)

Bye,
Bjoern

divinelycomical

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Jun 21, 2004, 10:28:34 AM6/21/04

to

I found the reply to your question difficult to understand!
An easy explination may be
Ho is in its conventional units of KmS^-1 Mpc

Simply convert Mpc to km and divide the conventional units by your
converted value of Mpc to give you the value in units of S^-1. As
the Km/Km cancel out to give you S^-1

Sam Wormley

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Jun 21, 2004, 10:50:47 AM6/21/04

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divinelycomical wrote:
>
> I found the reply to your question difficult to understand!
> An easy explination may be Ho is in its conventional units of KmS^-1 Mpc
>
> Simply convert Mpc to km and divide the conventional units by your
> converted value of Mpc to give you the value in units of S^-1. As
> the Km/Km cancel out to give you S^-1
>

See: http://www.google.com/search?q=71+km%2Fs%2F+10%5E6+parsec