(sixth dimension stuff)
That video doesn't really explain string theory very well. That's not really how the dimensions work... as someone in another forum said:
However, this is more an interesting piece of fiction than a meaningful representation of string theory. Also, the odd claim that you can only have 10 dimensions is flat wrong.
In string theory, the "extra" dimensions are really, really, tightly wound space dimensions that are unobservable by beings in our universe. I don't really know why they matter, except for gravity leakage or something, just that they are necessary to prove string theory (I'm not a physicist, just friends with a lot of them). Anyway, I would just take the video as more philosophical than scientific. In string theory, dimensions have nothing to do with "alternate realities" or anything like that (at least not in the highly convenient way described in the video).
See
Antonfire's post about halfway down the page. Or just read up on string theory. You don't have to read very far to realize the guy in that video is full of it.
But anyway:
the only thing that can change anything is you
Under CD, yes. But, CD also implies that you must change EVERYTHING. Think of it like this:
Suppose we lump the entire existence of the universe together prior to the lotto and call it even A. We call the state of the universe during the picking of those precise lotto numbers event B. Then, we know that:
If A
then B
BUT, by going back in time, we create event A' =/= A. It doesn't matter what we do in A'. It can never be A.
Then, the statement
If A implies B
Then A' implies B
Is FALSE. We cannot use any information from A to determine what A' implies. A' In fact, under CD, A'
cannot imply B; it can only imply B'. B' might contain the event of picking the same lotto numbers, but it must differ in some aspect from B.
This is because CD is bijective: each event implies exactly one event, and each event can only be implied by exactly one event.
In other words:
If C implies E
and D implies E
Then C=D
And if F implies H
And if G implies not H
Then F does not imply G, and G does not imply F
Therefore, if we were to extrapolate the entire timeline of A, it would never again intersect the time line of A'.
(Of course, this logically violates CD, since they must have had some common point in the past.)
In short: under CD, you can't travel back in time.