Quantum mechanics tells us that the atom’s wavefunction can be in a superposition of states – simultaneously decayed or not decayed. So is the cat’s wavefunction also in a superposition of both dead and alive.
Physicists have been struggling for some time to figure out why our universe is so comfy. Why, for example, are the fundamental constants – like the mass of the electron or the strength of the forces – just right for the emergence of life? Tweak them too much and life, stars, galaxies, the universe as we know it wouldn’t exist.
The universe is big, but it’s peanuts compared to the eternally inflating multiverse. But just how many universes are there? What are they like? And most importantly, what can they tell us about … aliens?
One of the most startling possibilities is that our 3+1 dimensional universe may better described as resulting from a spacetime one dimension lower – like a hologram projected from a surface infinitely far away.
Imagine a universe in which the most elementary components are stripped of all properties besides some binary notion of existence or non-existence. Like, if the tiniest chunks of spacetime, or chunks of quantum fields, or elements in the abstract space of quantum-mechanical states can either be full or empty. These elements interact with their neighbors by a simple set of rules, leading to oscillations, elementary particles, atoms, and ultimately to all of the emergent laws of physics, physical structure, and ultimately the universe.
But… is the universe actually made of stuff? An increasing number of physicists view the universe – view reality as informational at its most fundamental level. But how big a memory bank would you even need to compute a universe? Seriously, let’s figure it out.
On this Space Time Journal Club we look at how gravitational waves can be used to search for extra dimensions of space!
There’s this idea that beauty is a powerful guide to truth in the mathematics of physical theory. String theory is certainly beautiful in the eyes of many physicists. Beautiful enough to pursue even if it’s wrong?
Some see string theory as the one great hope for a theory of everything – that it will unite quantum mechanics and gravity and so unify all of physics into one glorious theory.