Each person exists as an unchanging 4D worldtube in the block universe. At each slice of the worldtube there is a present, past and future.

However, there is a black box* which appears to exist in only one slice of the block universe at a time. How could this be explained?

I am not trying to attack the block universe concept, I am not trying to get into metaphysics and I am not trying to come up with my own crack-pot theory.

I would just like to know how a world tube can contain something, a black box, that exists throughout the whole worldtube, and yet creates the illusion of only existing in one slice of the universe at a time.

Is it an imaginary force like the centrifugal force? Or an emergent phenomena such as temperature? Something else?

*The black box is consciousness, but I don't want to use that word as it seems to make physicists run away screaming.

  • $\begingroup$ The key word is "appears". Consciousness is a subjective biological process, and has no bearing on the validity or invalidity of physical theories. The fact that an schizophrenic person can hallucinate the existence of a pink slug that can travel faster than light is not a physical phenomenon that disproves special relativity. Trying to attribute consciousness to a fictitious force or other base-level physics concept is bound to fail because we simply don't have enough information yet to rigorously determine how consciousness works, other than that it's probably a biochemical illusion. $\endgroup$ May 10, 2014 at 12:49
  • $\begingroup$ What you are talking about is indeed the hard problem of consciousness. If you believe it's not you probably don't understand what philosophers mean by consciousness. The currently known laws of physics don't offer any answers whatsoever to your questions. In fact in the framework of modern physics your questions don't even make sense because they don't fit into that framework. I do agree that the issues you are raising are very important and hope we will find an answer one day but right now you can't expect to find an answer in physics. $\endgroup$
    – Tesseract
    May 10, 2014 at 12:58

2 Answers 2


What you're asking about is philosophy not physics, and this is why it's philosophy.

Your question is just another varient on Zeno's arrow paradox. This boils down to if velocity is $dx/dt$ then at any instant in time $dt = 0$ and therefore $dx = 0$ and nothing can move$^1$.

The answer is that there is no flow of time in physics. Spacetime is a 4D manifold and time is just one of the labels we use to identify points within this manifold. For a flow of time to exist there would have to be some extra physical parameter $\lambda$ that would allow us to define $dt/d\lambda$ and no such physical parameter exists$^2$.

It's certainly true that we conscious beings have the perception that time is flowing, and you could use Zeno's argument to suggest that $d$(consciousness) has to be zero at every instant, but this is a question about the way consciousness works, not a question about physics.

$^1$ Apologies to any philosophers who may be reading this for my butchery - that's physicists for you

$^2$ Actually general relativists use exactly this type of parameterisation all the time, but $\lambda$ is just an affine parameter and has no physical significance


Given a 1D universe containing a point that moves along a line, you can draw a 2D graph of position vs time. The graphs shows a fixed image of all time. But the ball is not fixed. It exists as a slice.

The situation is similar in space-time. Yes, it is 4D. Yes our past, present, and future fill a block. But we only exist as a slice at the present.

Space and time do make a 4D construct, but that does not mean time is the same thing as space.


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