David Albert - What Exists?

What exists

• David Albert is trying to understand what exists in reality beyond the obvious objects

• This question has been a major concern for Physics for a long time

"I'd like to ask my friends is what exists"

Developments in Physics

• Physics underwent a major evolution regarding what exists

• It was once hoped that we could account for everything based on the motions of material particles until it became clear that this wasn't the case.

• At least one more fundamental structure, known as fields, was needed to explain the architecture of the world

• There is an ongoing debate about what the appropriate ontology of quantum mechanics is

"I think quantum mechanics paints a picture for us where the fundamental objects are Fields but Fields not of the kind we're used to"

Limitations in Describing Fundamental Categories

• Everything in the world falls under one of the two categories: objects that are reducible to other objects and objects that are fundamental

• The challenge is describing the fundamental category because its nature is elusive

• The ontology of particles and fields is currently the most promising avenue of research

"seeing the extent to exploring the extent to which we can get along with just recognizable physical recognizable fundamentally entities like particles and fields, but exactly what it is to be a fundamental physical entity is itself an open question"

Debates on Ontology and Quantum Mechanics

• There is an ongoing debate about what exists in the world according to quantum mechanics

• One question is what the appropriate ontology is and what exactly the theory is telling us

• No one agrees on the right way to answer these questions yet

The nature of reality

• David Albert suggests the best bet is that the world is as it appears to be.

• This doesn't lead him to the many-worlds interpretation.

• Instead, it leads him to a strange picture of the dimensionality of space, which is much higher than previously thought.

Interpretations of quantum mechanics

• There are various ways to make sense of quantum mechanics on the market now.

• None of them have settled yet and do not have a serious alternative and none try to go deeper.

String theory and quantum mechanics

• String theory is just a variation of quantum mechanics.

• There are basic principles of quantum mechanics, such as linearity of equations of motion and representation by states in Hilbert space.

• These principles are common to string theory and all other theories.

Nominalism and physics

• Nominalism is a philosophical approach that tries to avoid any entities that do not play a causal or explanatory role.

• There are serious attempts by Hartree Field to see how to reconstruct physics without having to commit to the existence of abstract objects, such as numbers.

• Whether these projects will succeed and the degree to which they'll succeed remains an open question.

• David Albert suggests trying to produce as concrete and mechanical a picture as possible because physics is hard and philosophy is hard.