On 2012-09-17 13:48, Richard Brown wrote:
Another measure of the size of the IPv6 address space... Back on
World IPv6 Day in June 2011, Dartware had a barbecue. (Why? Because
the burgers had 128 (bacon) bits and we served IP(A) to drink :-) You
can see some photos at:
http://www.networkworld.com/community/blog/scenes-ipv6-day-barbecue
But we came up with another interesting measure for the vastness of
the IPv6 address space:
If an IPv4 hamburger patty has 2^32 (4.2 billion) unique addresses in
its 1/4 inch thickness, how thick would an IPv6 hamburger be (with
2^128 unique addresses)?
The answer is... 53 billion light-years.
Just got to playing with this today, trying to put it in some sort of
perspective. First off, lets bring that down to human-sized numbers,
using standard units used in astronomy:
2^94 inches = 16 gigaparsecs + 304 megaparsecs + 322 kiloparsecs + 752
parsecs + 2 lightyears + 57101 au + 23233 earthradius
(Gigaparsecs isn't very common, but that's because it's a bit big.)
So... How big is that? What can we compare it to? Well, let's start
at the top: does this thing actually fit in our universe?
The size of the observable universe is set by the Hubble Constant and
lightspeed: The Hubble Constant is the rate of growth of expansion in
the universe - the redshift phenomena. The further away you look, the
faster things are moving away from us. At a certain point, they are
moving away from us faster than light, meaning that light coming from
them would never reach us.
That's about 14 gigaparsecs away. (Adjusting for such things as how
much they will have moved since you measured them. There's a whole
rabbit hole to go down for this, on Wikipedia alone.) Which means the
observable universe is about 28 gigaprsecs across. (Now you can see why
gigaparsecs isn't a common unit.)
So our hamburger patty would fit inside it - but you wouldn't be able
to see one end from the other. Ever. In fact, while someone at the
center could reach either end, once they got there they'd never be able
to reach the other. They wouldn't even be able to get back to where
they started.
Which of course means that even if you ate at lightspeed, you'd never
be able to eat it.
(Oh, and if it still has a radius of 3 inches - standard 1/4 pound
burger at 1/4 inch thick - it's got a volume around that of 11,000
Earths, and a mass of about 1,400 Earths, about 4.6 times the mass of
Jupiter.)
It's straightforward unit conversions. There are 2^96 IPv4 Hamburgers
at a quarter-inch apiece. That's 2^96 inches/4 (2^94 inches).
Switching to decimal units, 1.98x10^32 inches; 1.65x10^27 feet;
3.13x10^23 miles; and then continuing to convert to light-years.
A good tool for this kind of wacky unit conversion is Frink
(http://futureboy.us/fsp/frink.fsp?fromVal=2%5E94+inches&toVal=lightyears),
which can do this in one shot. Simply enter:
I prefer the 'units' program, which is usually a standard utility on
Unix-like boxes. (If not in your distro of choice, finding the GNU or
BSD versions is left as an exercise for the reader. ;) )
Daniel T. Staal
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