Using the google calculator we can take a kind of almost experimental approach to planck units, explore, build up our concepts, try them out. It is easy---a few posts will show what I mean. So here's a brief tutorial.
1. get to know hbar (Planck's constant)
Think of hbar as being the product of amounts of energy and time. Check that by typing things like this into google
hbar/minute
hbar/year
It will give you answers in energy terms----small amounts of energy.
If you like BTU or calories or foot pounds you can always ask for the answer in those terms
hbar/hour in foot pounds
Personally I am most comfortable with ordinary metric units like second meter joule newton, but I want to emphasize that the google calculator works with a wide range of units and will give you answers in pretty much any units you happen to like. It knows how to convert and it does what you tell it.
2. Think of hbar as the product of (typically small) amounts of force x distance x time.
Try pulling hbar apart using the calculator. Take hbar, pull out some length, then pull out some time
(hbar/inch)/day
It will always turn out to be a force. Let's have the answer come out in pounds of force:
(hbar/inch)/day in pounds
(hbar/foot)/hour in pounds
Try putting the blue thing into google and see.
More later
Merged post follows:
This is the second post of this tutorial. The title of the post is
Your first planck unit--the Force :-D
1. Try putting this into google
c^4/G
Again, to emphasize that there's no metric bias, put this in
c^4/G in pounds
c^4/G is a natural amount of force. It's the Planck force. Remember it.
2. Besides the Planck force we don't have very much we have to remember. You already pulled apart hbar and you know it is made up of
force x length x time
Well what other natural constant do you know that involves length and time?
c
c is length/time
So what happens if you multiply
force x length x time together with length/time? You get force x area.
So let's try that. Multiply hbar*c and check to see if it is the product of some force with some area. The way we check is we put this in google:
hbar*c/square inch
That is, we multiply hbar and c together and then divide out any amount of area we please, square foot, square meter, square inch, square mile whatever. If hbar*c is the hidden product of some force with some area, then if we divide out some area we should get a force.
Just to show we're not biased let's get it in pounds
hbar*c/square inch in pounds
Merged post follows:
This is the third post in this short tutorial. The title of the post is
Your second planck unit---the Area
OK we picked apart hbar a little and we know it acts like it's made of a bit of force multiplied by other stuff.
And we teased apart hbar*c some and we know it acts like it is a force x area quantity... made of a small amount of force multiplied by some area.
And we know c^4/G is a force. It is a natural amount of force that doesn't involve any man-made units like inch or hour or foot etc.
So let's divide hbar*c by that natural force and see what we get.
Put this into google
hbar*c/(c^4/G)
or even better put this in
hbar*c/(c^4/G) in square inches
That is a natural amoung of area that doesn't depend on man-made stuff like joules kilograms etc. It's expressed in square inches, OK, but that doesn't matter, you could choose any unit of area to express it in---square yards, square millimeters... The quantity of area itself is natural.
And if you took highschool algebra you probably noticed that something could be simplified by canceling a c.
hbar/(c^3/G) in square foot
And we can make it look nicer by flipping the G up
hbar*G/c^3 in square miles
Your third Planck unit---the Length.
Try this in google
sqrt (hbar*G/c^3 ) in miles
This post has been edited by Martin: 10 January 2009 - 07:23 PM
Reason for edit: Consecutive post/s merged.

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for the electron. Note that it contains spin and not charge. The Reissner-Nordstrom metric becomes significant down around E-23 meters, IIRC. OK Martin the thing I need to ask you here is what of electron Schwarzschild radii of E-57? Is this beyond the pale of what may be described??? Normally I wouldn't care to be honest! Now, though, this ring singularity at E-13 meters is supposedly that thin and I suspend judgements...
. The reason I say normally I would not Kerr <> about the Schwarzschild radius is that I figure things really do fall apart into quantum foam in the Planck regime. I trust that the essence that I portray in my inhomogeneous electron study is indeed fulfilled at that level at least.
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