Hubble Constant

"beavith" wrote in message
...

however, give me a quick
primer in fractions...

does x/yx = x/y/x ?

reducing, i get

1/y and x^2/y

you should not be getting x^2/y

If we take x/y/x and arrange it like this ...

(x/y)/x

division by x is the same as multiplication by its inverse, so ...

(x/y)/x = x/y * 1/x = 1/y

On Tue, 22 Jun 2004 09:33:51 -0400, "John Zinni"
wrote:

"beavith" wrote in message
.. .

however, give me a quick
primer in fractions...

does x/yx = x/y/x ?

reducing, i get

1/y and x^2/y

you should not be getting x^2/y

If we take x/y/x and arrange it like this ...

(x/y)/x


ahhh!

so x/y/1/x would be x^2/y. thanks.....

it did seem like a bizarre unit.

division by x is the same as multiplication by its inverse, so ...

(x/y)/x = x/y * 1/x = 1/y

On Tue, 22 Jun 2004 09:33:51 -0400, "John Zinni"
wrote:

"beavith" wrote in message
.. .

however, give me a quick
primer in fractions...

does x/yx = x/y/x ?

reducing, i get

1/y and x^2/y

you should not be getting x^2/y

If we take x/y/x and arrange it like this ...

(x/y)/x


ahhh!

so x/y/1/x would be x^2/y. thanks.....

it did seem like a bizarre unit.

division by x is the same as multiplication by its inverse, so ...

(x/y)/x = x/y * 1/x = 1/y

beavith wrote:

so x/y/1/x would be x^2/y.

As long as you parse it as (x/y)/(1/x). Reading left to right, as a
calculator program might, i.e. ((x/y)/1)/x, would give a different
result, 1/y again. Same for x/(y/(1/x)). I think your original
problem with "x/y/x" is that you were parsing it as x/(y/x) -- but
going back to the original km/s/Mpc, I think it clearly has to be
grouped as (km/s)/Mpc.

Moral: use parentheses to avoid ambiguity.

(For expressing units you can also use exponential notation, e.g.
km·s^-1·Mpc^-1 -- I think you'll find this practice adopted by many
physics texts and journals. But it's ugly as hell in ASCII.)

--
Odysseus

beavith wrote:

so x/y/1/x would be x^2/y.

As long as you parse it as (x/y)/(1/x). Reading left to right, as a
calculator program might, i.e. ((x/y)/1)/x, would give a different
result, 1/y again. Same for x/(y/(1/x)). I think your original
problem with "x/y/x" is that you were parsing it as x/(y/x) -- but
going back to the original km/s/Mpc, I think it clearly has to be
grouped as (km/s)/Mpc.

Moral: use parentheses to avoid ambiguity.

(For expressing units you can also use exponential notation, e.g.
km·s^-1·Mpc^-1 -- I think you'll find this practice adopted by many
physics texts and journals. But it's ugly as hell in ASCII.)

--
Odysseus

On Wed, 23 Jun 2004 02:28:00 GMT, Odysseus
wrote:

beavith wrote:

so x/y/1/x would be x^2/y.

As long as you parse it as (x/y)/(1/x). Reading left to right, as a
calculator program might, i.e. ((x/y)/1)/x, would give a different
result, 1/y again. Same for x/(y/(1/x)). I think your original
problem with "x/y/x" is that you were parsing it as x/(y/x) -- but
going back to the original km/s/Mpc, I think it clearly has to be
grouped as (km/s)/Mpc.


that's right.
time to dust off the old algebra book for some light evening reading.

Moral: use parentheses to avoid ambiguity.

(For expressing units you can also use exponential notation, e.g.
km·s^-1·Mpc^-1 -- I think you'll find this practice adopted by many
physics texts and journals. But it's ugly as hell in ASCII.)

thanks, O, JZ.
quandary resolved.

On Wed, 23 Jun 2004 02:28:00 GMT, Odysseus
wrote:

beavith wrote:

so x/y/1/x would be x^2/y.

As long as you parse it as (x/y)/(1/x). Reading left to right, as a
calculator program might, i.e. ((x/y)/1)/x, would give a different
result, 1/y again. Same for x/(y/(1/x)). I think your original
problem with "x/y/x" is that you were parsing it as x/(y/x) -- but
going back to the original km/s/Mpc, I think it clearly has to be
grouped as (km/s)/Mpc.


that's right.
time to dust off the old algebra book for some light evening reading.

Moral: use parentheses to avoid ambiguity.

(For expressing units you can also use exponential notation, e.g.
km·s^-1·Mpc^-1 -- I think you'll find this practice adopted by many
physics texts and journals. But it's ugly as hell in ASCII.)

thanks, O, JZ.
quandary resolved.