Physical Constants........i'm confused!!

[Inka]

Hi can anyone help me??
I don't understand why we have physical constants like Plank's constant etc.
Why can we measure them but not derive them and how do we know that their not changing ( also what would happen if they did?)?????????????????

thanx Ink x

[thed]

You and the rest of us. For some reason these values are set in the Big Bang and appear to be highly sensitive to making the Universe 'just so'. It leads some, on the fringe, to suggest it is evidence of a 'designer'.

They may change with time but if they do observations of distant Galaxies are somehow consistent with them being the same as they are now.

[DarkDAVE]

Plank length is the minimum length before the general laws of physics no longer apply and you have to use quantum physics.

Plank time is the time it takes for light to travel the plank length. Measuring anything lesser than plank time is meaningless.

In quantum physics particles with radius that are smaller than plank's length can exist in many places at the same time. This is refered to as quantum weirdness.

The first big bang was thought to begin in the first unit of plank time.

read here for more details:

http://www.physlink.com/Education/AskExperts/ae281.cfm


Sincerely, David

[Joeblow93132]

Inka,

Let me give you a simpler explanation than the ones that Darkdave and thed gave:

Constants, are generally, variables scientists use in their formulas so that they would balance. For example, you may use pound or meter to measure weight, but the universe uses something different. In the formulas for pound and meter, each would have to have a DIFFERENT constant , which would convert the human measurements to universal measurements.

Another example is temperature: We use Celsius and Fahrenheit, while the universe uses Kelvin. If you wanted to use Celsius in your in a scientific formula, you would have to use a constant to convert it.

Of course not all constants are man made, there actually are physical constants the were not created for humans. But the only truely physical constants I know of, are PI and the speed of light.

Tom