So I get that a Planck length is the smallest length measurement that we have. But why?
I know it has something to do with gravity and speed of light in a vacuum. But why? Is it the size of the universe as early as we can calculate prior to the Big Bang? What is significant about it?
All the videos I see just say it’s a combination of these three numbers, they cancel out, and you get Planck length – and it’s really really small. Thanks in advance!
In: Physics
Nothing. It’s not important at all. It’s way smaller than anything we can measure. Absurdly, radically smaller than anything we could dream of measuring.
Now, it is approximately the smallest length that our known physics applies. Very approximately. This is just because it’s around the distance that gravity’s influence should become significant, and we don’t know how gravity works at such small scales.
The length itself is a cool idea. The length of a meter, or a second, is arbitrary. Why is light speed 299,792,458 metres per second? What if we said the speed of light is “1”. Let’s repeat this for several different numbers, like the gravitational and planck constants. Now every other unit, like distance and time, can be derived from one of these. By combining these constants, we can derive other units. For instance, in this system, a unit of time will be sqrt(hG/c^5 )
Now in our regular units h and G are very small, while c^5 is *insanely big* so the resulting time unit is ludicrously small.
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