Quantized Spacetime

star field


2 Why Quantize?

A spacetime quantum would be rigid to forces other than gravity. This provides the basis for special relativity, which explains why objects speeding by appear to shrink in length and time, slowing their aging, and making it possible to think of visiting the stars. Gravity would compress a spacetime quantum in the direction of the gravitational field. This would accelerate objects towards a planet’s surface, shrink time and length, and ultimately cause stars to collapse into black spheres.

Which brings up an important question. Why think of spacetime being quantized when we have always thought of it as being continuous? We’ve done pretty well in discovering amazing objects like quarks and black holes, and envisioning trips to the stars. Why change? Are we actually living in a different universe to the one we thought we were in?

Well, it looks like we are. We have recently been shocked to find that the universe, as we know it, is only five per cent of the total universe. The other 95 per cent is made up of two unknown entities, provisionally called dark matter and dark energy. We have spent hundreds of millions of dollars searching for particles of dark matter and not found one. And we know even less about dark energy. We are already living in a different universe to the one we thought we are in, and we are struggling to understand it. Thinking about spacetime the wrong way may be our problem.

normal, dark,matter, energy

The universe we have discovered amounts to only 5 percent of the entire spacetime universe. The other 95 percent is made up of two mysteries: dark matter and dark energy (Picture credit: NASA). 


And there are a number of problems with continuous spacetime. As its name suggests, continuous spacetime is not split up into little pieces: it is continuous and infinitely divisible. Points in it can be infinitely close together. That can leave you with a piece of spacetime that has no size at all. Which, in turn, makes strings of infinities appear in your theory.

So, you conjure up opposite infinites to balance them out to find out what is behind them. Richard Feynman, one of the inventors of this trick remarked, “It is what I would call a dippy process!  . . . hocus pocus . . . perhaps the idea that two points can be infinitely close together is wrong.” And one has other concerns. Like unease about an entity with two totally contradictory properties, being both a particle and a wave. Or in assuming that a black hole can be stabilized by an object that does not obey the laws of physics.

It is difficult to believe that nature supports these paradoxical phenomena. The contradictions may perhaps arise because a continuous spacetime does not match the structure of the contents of spacetime. Matter and energy exist in discrete bits, or quanta: indivisible particles of matter, indivisible quanta of energy. One would expect them to be embraced by a quantized spacetime. Trying to fit them in continuous spacetime may be like trying to fly an airplane that defies the laws of flight. 8/14/2020 5:36 2

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