While I was in France recently I decided to make one of my parallel self a millionaire. It's very easy and you too can do it if you want.
How to do it? First you have to check how the national lottery of the country where you are works. In France, a lotto ticket costs 2 euro, you have to pick five different numbers from 1 to 49 (included), and one 'lucky' number from 1 to 10 (included). To win the big price, all your numbers must match the winning numbers. If you do, you can earn up to a few millions.
We are going to play this -otherwise pretty stupid- game in such a way that we are sure that we are going to win in at least one parallel universe.
To pick your numbers, go on one of the numerous websites that offer live stream of quantum random numbers, for example the ANU Quantum Random Number Server (http://qrng.anu.edu.au). From there pick a long enough random number. In my case I got this one (in hexadecimal):
You should start to see where this is going. If the multi worlds interpretation of quantum physics is correct, and assuming the number really was computed using a pure quantum process, then there exists one parallel universe for each possible values of this random number.
Now that the universe has been separated into multiple equi-probable versions, only differentiated by this number, we can start to pick our lottery numbers. I used a simple python script that would generate the 5 + 1 numbers from the initial random number I got. The algorithm is not very important, the only difficulty is to make sure that we don't get two times the same number, and to ensure that each possible set of values has an equal chance to appears.
In my case the numbers I played are:
[28, 31, 20, 12, 1] 8
And I know for sure that all the other possible numbers have been picked in different universes. Think about it: there are universes where you are right now reading the same web page, with the only difference being that those numbers (and the initial random number) are different.
Now, assuming that there is no cross correlation between the ANU Quantum Random Number Server and the French lottery, I can be sure that in at least one universe I got the numbers:
[09, 20, 26, 27, 47] 07
Which happens to be the winning numbers of the day I bought the ticket.
I can know rest assured that somewhere in the multiverse, one of my parallel self did actually win the lottery.