Stránky Jana Nováka

The climate was always changing on Earth, but it is interesting that the beginning of global warming period in last 100 years matched with the beginning of industrial revolution when we started to pollute air heavily. Is it by accident or is there some correlation? This is our reaction to talks of Greta Thunberg from the point of view of theoretical physics…

One of the most quickly developing mathematical disciplines is algebraic geometry.  People found a solution for such a hard problem as Fermat last theorem by this. It is also useful in physics. We present a part concerning plabic graph, which has connections with amplituhedron physics.

Quantum Gravity is so difficult subject, because we don’t have so far any experimental data from the Planck scale. We need to solve many different issues simultaneously as nonlocality, background independence, or dimensional reduction for solving this problem. We claim that it is possible to formulate a different approach from all known paradigms, which is based on ideas of causal set approach, loop quantum gravity and string theory. We present the basic idea.

My contribution at 38th Winter School of Geometry and Physics in Srní 2019. My talk was about construction of Quantum Gravity, which I called Ring paradigm. Mathematical apparatus of this theory should be hidden in parts of algebraic geometry and topology.

There are many approaches to Quantum Gravity. We have string theory (ST), loop quantum gravity (LQG), causal dynamical triangulations (CDT), causal set approach (CSA) and many others. There are some common features for all of these theories. We discussed them briefly. We claim that the mathematical apparatus for Quantum Gravity is hidden in foundations of ST, LQG and CSA. We formulate the RT-paradigm and we wrote a list of open issues.

We formulate one mathematical problem, which will be useful in Quantum Gravity problematics. We will call, that a circle with finite length and finite circumference, which could be deformed, is a ring: let’s have a finite collection of N rings, which could not touch. Derive a formula for number of non-homeomorphic structures, which could be constructed from this finite collection of rings; Every two rings could be linked only once, they could not be knotted or twisted. We don’t consider the Brunnian type of ring.

Discrete causal approach to Quantum Gravity is a quite new subject of studies in the quantum gravity community. We discretize spacetime to points and we put a binary relation on this set. This serves me as a motivation for formulating a mathematical problem, which could be useful in the discretization problematics.

Causal set approach is a promising theory of quantum gravity. It gave us already a striking discovery, which is the value of the cosmological constant.

Causal set approach to Quantum Gravity is a quite new theory developed at late 80’s and 90’s of last century. It is a discrete approach to Quantum Gravity, by contrast with string theory or loop quantum gravity. And it is the only theory so far, which gave us a plausible bound on the value of the cosmological constant! These are slides from my lecture in Nuclear Physics Institute in Řež in Czech republic.