25th Oct 2009
What if we unassume?
My last (and the final) lecture at Q2C: Fotini Markopoulou’s “Creating Spacetime“. (And yes, I wonder how many times she’s heard a Marco Polo joke…).
Maropoulou is a founding member of PI, and a theoretical physicist whose current interest in quantum gravity, and more particularly, how can we get out from under the dilemma that we have with General Relativity and Quantum Particle Theory. Namely this: while both of these have been proven over and over again, and hold true in the right scale, we can essentially push either theory to arrive at a value of infinity (for General Relativity, it’s at the big bang, and for Quantum Particle Theory, it’s in the distribution of particles that can generate additional positrons and electrons after being already split).
So if we have the two biggies breaking down, then what that indicates is that we don’t really have the full/right answer yet.
Additionally, while we know a great deal about the stuff we can see (and as we’ve heard over and over again), there’s a whole lotta stuff in our universe that we know nothing about – i.e. dark matter and dark energy, and so on (though Markopoulou pegs the unknown at 95% instead of 70%). Leaving physicists with a lot of questions, but no definitive answers …yet.
Markopoulou set out to explain to us civilians what she thinks needs to happen. She started by challenging out notions of time – for if we think about it in physical terms, “time”–the idea that something happened to us before–is tied to our ability to perceive the photons and sound waves that come at us in a certain arrangement. So let’s say she’s giving the same lecture to the same audience, but there’s a black hole hiding behind the lectern that be stealin’ all her photons and voice. In this case, in “theory”, though the lecture does indeed take place, it does not take place for the audience. It’s not in our “time”.
This little intellectual fissure opens up what Maropoulou really wants to go after, and that’s the notion of spacetime (it’s a biggie!). For, if we are to resolve the issues in the way of understanding quantum gravity, then something fundamental needs to change. Like maybe space is NOT a fundamental; rather, it’s emergent. In the sense of “A property of a collection of simple subunits that comes about through the interactions of the subunits and is not a property of any single subunit.” She used the example a river – where we can identify and understand the properties of a river, but can also understand underneath that, that the “riverness” of river is emergent, since the river itself is composed of atoms, which are the “building blocks” of the that riverness.
To follow the analogy then, space is not in and of itself, but emergent from matter. Okay. Boggle that one for a minute.
In terms of theoretical models, what this does is remove an essential problem in the assumptions of General Relativity (that space was always there), and curtails the “random dropping in of Einsteinian equations” to make things work, which is the way things are done now.
Markopoulou went on to show some comprehensible math as to how and why this might be possible via triangle diagrams that lead to our view (the cube) versus what we can call the network view (where all things are simultaneously everywhere). It’s also a nice way to answer for the fact that the universe is a homogeneous temperature even though we know that there are certain parts that have never touched.
She was very clear that we are far out into theoretical models in this. We can’t yet measure it or prove it. But, it’s tantalizing to think on it.