A direct link to the above video is at http://www.youtube.com/watch?v=UuAvMhTtlFE
This new video accompanies my blog entry You are a Point at the Center of Spacetime, published last August. Now I'd like to tie the ideas in this video to a blog entry that came a month later, called Light Has No Speed.
Last time, in Time's Illusions, we looked at two definitions of the word "now":
- "Now" is what I see at this instant. This includes what I see when I look up at the stars: even though I know it took years for their light to reach me, their light is reaching me right "now".
- "Now" is what's entangled with this very instant, and that's how the quantum world's instantaneous "spooky action at a distance" effects occur. "Now" is not what I see when I look at a star that's ten light years away, because the time it takes light to travel means that I won't be seeing what that star looks like "now" until ten years in the future.
A point in 3D space can, by virtue of it being of indeterminate size, be infinitesimally small (like the point we're most familiar with from geometry), or infinitely large, encompassing all of 3D space. In my book, and blog entries like The Flipbook Universe and What's Around the Corner, I've been asking people to imagine that this infinitely large "point" would be a "frame" of space (with no time), and each 3D frame is one planck length away from the next to create 4D spacetime.
A point in 4D spacetime can also be infinitesimally small (like the tip of my nose at 3 p.m. tomorrow afternoon, a very specific location in space and in time), or it can be infinitely large. What does an infinitely large point in spacetime encompass? In other words, which of the two "now"s listed above should we be thinking about here?
If I were to say that the infinitely large version of that point is the entire universe at 3 p.m. tomorrow afternoon, I would only have enlarged the space aspect: but I also need to enlarge the duration, the 4D element.
In Light Has No Speed, we looked at a presentation by physicist Peter Russell which explains that for a photon, there is no space and no time. From a photon's point of view, it travels instantaneously from a star 100 light years away to an observer such as you or I. So is our 4D point of infinite size like a photon, potentially encompassing all of our universe's timeline from its beginning to its end in one single instant?
Here's an additional clue from Mr. Russell to throw into this: for a photon, there is no non-locality, and the photon is "outside" of spacetime. So from the sounds of it our photon is not in the fourth dimension. Where is it then?
We know that non-locality is part of our universe, as it and other "spooky" quantum processes have been proven to exist beyond a doubt (we've talked about this in such entries as Our Non-Local Universe and Local Realism Bites the Dust). So is our 4D point in its largest state encompassing the "now" of non-locality? We've talked many times about how it's so easy for us to forget that the star we see in the sky is really not part of our "now" because of the time it took for the light to arrive here - looking at a star is looking back in time. The "now" of non-locality and quantum superposition allows for instantaneous correlations to occur at great distances, because our "now" is not what we see when we look into the sky.
Is it better, then, to think of our infinitely large 4D point that way: as encompassing the quantum world of instantaneous entanglement and non-locality?
Here's how I prefer to think about it - both definitions of "now" apply, because you and I are actually a point in the fifth dimension rather than the fourth. And just as trying to relegate "up/down" or "forward/backward" to a specific dimension within a 3D space makes sense only from a particular reference frame, thinking about these two versions of "now" makes more sense when we realize that our current "observation point" is in a frame of the fifth dimension, not the fourth. This is what Einstein came to believe as well: that our reality is defined at the fifth dimension, where the field equations for gravity and light are resolved.
Believing that our "now" is only in the fourth dimension leaves us thinking that the two arrows we're looking at here are not compatible. My diagram shows us how Peter Russell can say that light is not part of 4D spacetime, and light is not part of non-locality - because light is at right angles to spacetime.
Enjoy the journey!
Next - Is Spacetime Flat or Curved?