Science fiction, science fact: reports from the frontiers of physics

What is space?

Is space continuous or is there a smallest length scale we can't break down further? What would that mean for the way we do physics? What is geometry of space? To find out, vote for the space question and read these articles:

• On Plus: Quantum geometry — is space made up of tiny chunks?
• On FQXi: High fidelity — is space analogue or digital?

How did the Universe start?

What does modern physics say about the origin (or non-origin) of the Universe? And how can we test these theories? Vote for the start of the Universe or read these taster articles:

• On Plus: What happened before the Big Bang? — the answer will make your mind bubble.
• On FQXi: The holographic Universe — turning the Universe into a hologram to understand the birth of the cosmos.

Does infinity exist?

Are there things in the Universe that are actually infinite, or is infinity just a concept? How does mathematical infinity relate to transcendental and physical infinity? And can pure mathematics shed new light on these questions? Vote for infinity, or read these articles:

• On Plus: Cantor and Cohen: infinite investigators — why there's more than one infinity
• On FQXi: Taming infinity — a theory of everything is within reach if you know how to handle infinity.

How many dimensions are there?

Are there more than the three spatial and one time dimensions we can perceive? If yes, why can't we see them and can we detect them in experiments? Vote for dimensions or read these articles:

• On Plus: Hidden dimensions — exploring string theory's hidden dimensions.
• On FQXi: Testing times for natures constants — how clocks an open the door to extra dimensions.

What's the role of chance in the Universe?

Did chance have a hand in the early stages of the Universe? What does this mean for physics and how can we calculate the probabilities of different outcomes? To find out, vote for chance or read these articles:

• On Plus: Lambda marks the spot — is the biggest mystery of theoretical physics, the cosmological constant, a result of chance?
• On FQXi: Phantasms of infinity — can you define probabilities in the face of infinity?

Is the Universe complex or simple?

Is everything in the Universe "computable"? How does complexity emerge from simplicity? What are the limits of mathematical logic and how do they impact on physics? Vote for complexity vs simplicity, or read the following taster articles:

• On Plus: Omega and why maths has no TOEs — complexity and why there's no mathematical theory of everything.
• On FQXi: Baby steps — why did the Universe start simple?

What is information?

What does information really look like? Are there fundamental laws of information processing? And can they lead us to a physical theory of everything? Vote for information and read these articles:

• On Plus: The illusory Universe — what happens to information when it falls down a black hole?
• On FQXi: DoubleThink — storing information using quantum physics.

Will there be a theory of everything?

Finding a theory of everything is the biggest challenge for modern physics. Will we ever find it? And what will it look like? Vote for the theory of everything and read these articles:

• On Plus: String theory: from Newton to Einstein and beyond — on the currently hottest contender for a theory of everything.
• On FQXi: The quantum PlayStation — how the PS3 is helping physicists develop a theory of quantum gravity.

What is quantum cosmology?

We've all heard of quantum mechanics, the physical theory that describes the microscopic world so well. But what happens when you apply quantum mechanics to the whole Universe? If you'd like to find out, then vote for quantum cosmology or read our taster article:

• On FQXi: The holographic Universe — Take one universe, turn it into a hologram, find its quantum wavefunction and understand the birth of the cosmos.

Latest from FQXi

Mapping the ancestral history of spacetime in an effort to unite quantum mechanics and general relativity.