On 30 May 2012, at 18:16, meekerdb wrote:
On 5/30/2012 1:38 AM, Bruno Marchal wrote:
On 29 May 2012, at 22:41, meekerdb wrote:
On 5/29/2012 1:26 PM, Jason Resch wrote:
On Tue, May 29, 2012 at 12:55 PM, Bruno Marchal
To see this the following thought experience can help. Some guy
won a price consisting in visiting Mars by teleportation. But his
state law forbid annihilation of human. So he made a
teleportation to Mars without annihilation. The version of Mars
is very happy, and the version of earth complained, and so try
again and again, and again ... You are the observer, and from
your point of view, you can of course only see the guy who got
the feeling to be infinitely unlucky, as if P = 1/2, staying on
earth for n experience has probability 1/2^n (that the Harry
Potter experience). Assuming the infinite iteration, the guy as a
probability near one to go quickly on Mars.
Thanks for your very detailed reply in the other thread, I intend
to get back to it later, but I had a strange thought while
reading about the above experiment that I wanted to clear up.
You mentioned that the probability of remaining on Earth is
(1/2)^n, where n is the number of teleportations. I can see
clearly that the probability of remaining on earth after the
first teleportation is 50%, but as the teleportations continue,
does it remain 50%? Let's say that N = 5, therefore there are 5
copies on Mars, and 1 copy on earth. Wouldn't the probability of
remaining on Earth be equal to 1/6th?
While I can see it this way, I can also shift my perspective so
that I see the probability as 1/32 (since each time the teleport
button is pressed, I split in two). It is easier for me to see
how this works in quantum mechanics under the following experiment:
I choose 5 different electrons and measure the spin on the y-
axis, the probability that I measure all 5 to be in the up state
is 1 in 32 (as I have caused 5 splittings), but what if the
experiment is: measure the spin states of up to 5 electrons, but
stop once you find one in the up state. In this case it seems
there are 6 copies of me, with the following records:
However, not all of these copies should have the same measure.
The way I see it is they have the following probabilities:
1. D (1/2)
2. DU (1/4)
3. DDU (1/8)
4. DDDU (1/16)
5. DDDDU (1/32)
6. DDDDD (1/32)
I suppose what is bothering me is that in the Mars transporter
experiment, it seems the end result (having 1 copy on earth, and
5 copies on mars) is no different from the case where the
transporter creates all 5 copies on Mars at once. In that case,
it is clear that the chance of remaining on Earth should be
(1/6th) but if the beginning and end states of the experiment are
the same, why should it matter if the replication is done
iteratively or all at once? Do RSSA and ASSA make different
predictions in this case?
I think you are right, Jason. For the probability to be (1/2^n)
implies that there is some single "soul" that is "you" and it's
not really duplicated so that if it went to Mars on the first try
there would be zero probability of it going on the second. Then
the probability of your "soul" being on Mars is
Under the alternative, that "you" really are duplicated the
probability that some "you" chosen at random is on Mars is (n-1/
n). But in this case there is really no "you", there are n+1
people who have some common history.
The probability bears on the first experiences, which are indeed
never duplicated from their 1-pov, and we ask for the probability
of "staying" on earth. It is equivalent with the probability of
always getting head in a throw of a coin. So, from the perspective
of the guy who stays on Earth, he is living an Harry-Potter like
No more than the guys who went to Mars. If they compare experiences
they will find that although they only had probability 1/2 of it
happening, they all went to Mars.
They almost all went to Mars ... eventually, with one exception.
Besides this was just used in a protocol where the observer is the one
looking his friend, that is the exception. It is his 3-view on the 1-
view of the guy who never succeed to go on Mars. I have a collection
of strategies that he can try, like introducing delays, or using
random coin between "original" and "copy", unfortunately for the guy
remaining on earth, by "definition", he cannot succeed, and he will
have hard time to believe things are not conspiring against his will
to go on Mars, and this proportionally to the ingenuity developed to
assure to be the one going on Mars.
If you make that experience, the chance to go on mars is always rather
great, but of course, we, the spectators, will have to live with the
unlucky (from its first person view) who remains on earth.
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