What was Skynet Thinking?

A lot of people have a wonky understanding of time travel, based mostly on Back to the Future.  There probably isn't any such thing as time travel, so in that sense I guess anything you believe about time travel is true.  But the common view, that someone going back to the past from the future is able to alter events in the past from how they already happened, doesn't even make sense.

When we think of traveling to the past, we always think of this in terms of us, now, going to the past, and not in terms of someone else from the future coming to the present, so we we tend to think that we can change it.  Really, any "change" you make was already made, by you, before you left, and could have been recorded by historians if they had bothered to write about it.

It's an almost understandable mistake, due to our perspective.

But what the heck was Skynet thinking?

The Cosmic Order

Sometimes, it's comforting to know that, at the end of the day, there are a few basic principles which govern all interactions in the universe, and that they are always the same principles; the ones you've known your whole life.

No, I'm not talking about physics.  Nor about math.  I'm talking about principles much, much deeper, much more cosmically valid that those silly math and physics.  I'm talking about Murphy's Laws.

Today, I had these foundational constraints of existence verified in a particularly potent manner.

The Uncertainty Principle and Energy Non-Conservation and Why Your Textbook is Wrong

I read this all the time, in physics books and articles and on the internet: Apparent violation of conservation of energy is possible at the quantum scale for very short periods of time due to the Heisenberg uncertainty relation:
∆E∆t ≥h/2π
In that equation, ∆E is the "uncertainty" in the energy and ∆t the "uncertainty" in the time, meaning the accuracy to which we are able to measure these values.  The h in the equation is Planck's constant (which I didn't write as h-bar because I didn't want to encode LaTeX for one equation).  The two are inversely proportional, so as one goes up, the other must go down, so for short times, you can get enough "free" energy to send a particle through an energy barrier.

This is wrong.  Wrong, wrong, wrong.

Why Travel to Hyperspace Would Instantly Kill You

So, I've wondered a lot about a way to construct a "system of magic" (as often appear in modern fantasy works) from a collection of physical laws.  And until I got carried up in classes last semester, that was one of my main focuses of attention.

I was thinking that, in an alternative universe, there's no reason why they should have the same number of spatial dimensions as us.  So why not four, or five, or ten?

Because if you traveled to four-dimensional space, then you would find your skin insufficient to contain all of the air, blood, half-digested food, and maybe even internal organs that now find an extra degree of freedom within which to diffuse.

Five and higher dimensions makes it worse; the many things inside of you that keep you alive would disperse and splatter even faster.

So far I have discovered that to have any sort of meaningful adventure in a parallel universe, it must have the same number of spatial dimensions as we do (namely 3), it must have at least one time-like dimension, the electromagnetic interaction must exist and must recognize and interact with your electrons and protons.  Gravity would be nice, and I don't know enough about weak and strong interactions to know if they would be necessary.

http://abstrusegoose.com/457

There are most likely other limitations and dangers in such fantastic travel that have not yet come to mind.

In short, the inter-universe questing of children from our universe can never be to any world truly alien from our own.  Which is very sad.

Update: spam bots kept specially favoring this multi-year-old post in particular with travel blog advertisements disguised as comments, so I have disabled comments on this post.