Time Traveling?

One of the great paradoxes in physics is the “arrow of time”. The vast majority of mathematical expressions that describe the world we live in work equally well if time is going either forward or backward. Newton’s Laws give their solutions either way as do the simple and elegant field equations of electromagnetism and gravitation. (Entropy is the signal counter example.)

The odd thing about this is that even though classical physics says we should be able to go back and forth in time, we can’t. Or at least it doesn’t appear that we can and we certainly don’t observe many time travelers coming back from the future to observe historically interesting events (like the present election). The lack of time travelers is probably the most compelling proof (when seen in light of the Copernican Principle) that time travel is, for our intents and purposes, impossible.

The situation in quantum physics is similar but has an interesting twist. Early on in the exploration of the wave nature of matter it became clear that there was nothing to forbid matter from having a mirror image that we generally call “anti-matter”. Most subatomic particles have anti-particles. The proton has the anti-proton. The electron has the positron. The neutrinos have the anti-neutrinos. Some particles, like the photon, are their own anti-particle.

Mathematically we can describe an anti-matter particle as the time-reflection of the normal matter particle. A positron is the mathematical equivalent of an electron traveling backwards in time. This is rather interesting in of itself though we’re not sure if it means anything beyond simply being a neat math trick. Though it could help, if there is a preferred directionality to time (the arrow of time), to explain why we see so much matter and so little anti-matter. (There should be an exact balance between the two according to the simplest explanations of the Big Bang, but since we think things are more complicated than that people haven’t read too much into the imbalance and certainly no one has seriously suggested (as far as I know) that the imbalance is a result of the arrow of time.)


I’m reading NT Wright’s book “Surprised by Hope”. Early on in the book, Wright discusses our common tendency to put our hope for a better life into heaven rather than on insisting making into an earthly reality. He points out that the words in the Lord’s Prayer “Thy Kingdom come on Earth as it is in Heaven” are a powerful reminder that what Christians really believe is that in the future the heavenly “now” will become the earthly reality, with Heaven subsuming Earth into a transformed existence. It’s not that Earth passes away. It is that our Hope is founded on the belief that Earth is joined to the Heavenly reality, God’s reality, and that by so doing the Earth is remade.

Wright says “Easter was when Hope in person surprised whole world by coming forward from the future into the present.”

The idea is that the Jesus of our future has come back to be revealed to us in the Easter moment. In other words Jesus is a time traveler – in at least a poetic sense – though possibly in a theologically and maybe physically literally sense as well.


When matter and anti-matter collide the resulting explosion has the effect of converting the sum total of their rest mass into energy (E=mc^2) I tend to imagine this conversion into pure energy as an act of destruction because nothing of the previous state remains. Yet what it really represents is a liberation of the potential energy (energy being by definition the ability to change the state of system) that has been trapped in the mass of the particles.

So, thinking mostly allegorically and speculatively:

If Jesus coming back into our time were to do that, then his “collision” with our reality would be similar. Energy and light would be released. Most importantly there would be change simply due to the interaction between objects moving in different directions in time. The Easter event then could be seen as the hinge moment in our history when we received the necessary energy to begin to remake the Universe.

Not sure how far you can push this, but it’s certainly, to me, a neat thing to think about on a Friday afternoon that is the Eve of All Saints.

Author: Nick Knisely

Episcopal bishop, dad, astronomer, erstwhile dancer...

4 thoughts on “Time Traveling?”

  1. So what about the Transfiguration? This seems to me perhaps as a visual, aural, specific breakthrough moment that would be emblematic of what you were talking about.

  2. John – time reflection (mathematically) is changing the “t” in an equation (the time variable) to “-t”. It’s functionally the same as changing the “x” (spatial variable) to “-x”. Conceptually think of watching a physics experiment in a mirror. It works either way and that’s why we say that there’s a spatial reflection symmetry. Mathematically speaking the same should be true for time, but in actual experience it’s not. (You can’t un-stir coffee and no one really knows why.)

  3. Thanks Jamie. In short answer to your question ‘yes’. Actually it could explain the energy and light that surround angelic apparitions too. (At least if we want to extend the allegory as far we can…)

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