# Bizarre coincidence with Huble Shift and Planck seconds?

1. Mar 6, 2009

### caasi

Edit: Save yourself the read, I blundered, any admin or moderator who reads this, please feel free to lock the thread and delete it. Classic case of making an equation big enough that you don't realize everything cancels out.

This is my first time posting here, and just for the record my physics and math have rather decayed in the six years since I left school, so I could easily be making a stupid mistake. I was mucking about with trying to come up with some vaguely scientific sounding FTL or wormhole idea for a sci-fi writing excursion and decided, 'hey, let's check what the distance would be if some wormhole-thingy was allowed to be only as long as the extra distance that might result from a hubble shift if that shift had to be less then the distance light would cover in a planck second'

Obviously there's no science there, but I ran the numbers, hoping I'd get some less than a light-year distance, which might let me center plots around something that wasn't always inside planetary orbits.

So I worked out the distance light travels in a planck second (3x10^8 m/s)(5.39x10^-44 s) = (1.62x10^-35 m)... call it X

then converted the hubble shift to SI (70.8x10^4 m/s)/Mpc = 2.29x10^-18 s-1

I eyeballed the numbers and they looked appropriatly astronomical, so I used...

D = X/(hubble in SI x planck sec) = (1.62x10^-35 m)/((2.29x10^-18 s-1)(5.39x10^-44 s) = 1.31x10^26 m

Good number I thought, let's divide it by light years (1 Ly = 9.46x10^15 m)

Then D becomes 1.38x10^10 Ly... 'crap', I thought, that's no good, that's as big as the whole universe.

Then it hit me, that really is as big as the whole universe. 13.8 GLy, or 13.8 billion years, especially including the 4.0 km/s/Mpc margin of error on hubble's constant.

My first thought is that this is just a weird coincidence of numbers, my second thought was maybe not, and my third was even if not, then someone has likely done this before. Actually my second thought was to rerun the numbers and units from different angles and see if I got the same number, and I did.

Does this mean anything? I assume not, but I'd rather be formally told by someone with more knowledge in the field that I'm tilting at windmills then just throw my notebook out.

Last edited: Mar 6, 2009
2. Mar 6, 2009

### caasi

Okay, I caught my error

All I really did was divide the speed of light by hubbles constant, I used the planck second twice and it divides out. Big surprise, the speed of light divided by the hubble constant gives you the rough age/distance of the universe.

If the sight has a moderator who can lock and delete threads, please feel free to do both. Sad to see how rusty I've gotten, glad to see I could at least catch the mistake ;)