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.
Galileon cosmologies are used for modelling of the late time cosmic acceleration. These are the slides from the seminar, which I held in CEICO in Czech Academy of Sciences 3.5.2018.
Galileon gravities is one approach to modified gravities. I use it in the context of cosmology in the proof of viability of these models.
I reccorded yesterday my intepretation of two Scriabin’s composition’s op.11, no.1 and op.11, no.5.
There were produced gravitational waves during the cosmological inflation epoch in the evolution of the Universe. First step for obtaining the spectrum is to do the perturbation of action, which composes from Einstein-Hilbert action and the action for scalar field.