C.Szybka:Backreaction for Einstein-Rosen waves...

[Maxim Khlopov]

VIA lecture by Prof. Sebastian Jan Szybka ''Backreaction for Einstein-Rosen waves coupled to a massless scalar field'' was given on 16.12.2016. It's presentation is attached.
The following questions were put:
Shantanu: Can effect of inhomogenieties mimic dark matter. (David Witshire said in his talk in this series that it could)
Steve Branchu: why we don't know g_U ?
Houri Ziaeepour: What is the physical meaning of parameter lambda ?
Shantanu: Just a comment for other particpiants. David Wiltshire also gave a a very interesting talk (although at a non-standard time) which is worth watching

Houri Ziaeepour: But somehow we must be able that relate it to other properties of the Universe, otherwise a cosmological constant can do very well the job of explaining observations.

Houri Ziaeepour: I meant relating lambda to other properties.

Shantanu: A question to Prof. Obukhov. Has anyone worked on backreaction problem in Einstein-Cartan gravity?

Yuri Obukhov: Not, not to my knowledge

Shantanu: (or a question to Sebastian if he knows)

Houri Ziaeepour: Yes. Bukert.

Shantanu: Let me ask an observational question

Houri Ziaeepour: But to explain accelerated expansion, one needs a large curvature which is against observations.

Shantanu: Is there any observation which will settle the controversy between Wald and others (you mentioned earlier)

Houri Ziaeepour: What is called the backreaction of anisotropies can explain apparent accelerating expansion only if there is a large curvature.(Bukert 2002).

Houri Ziaeepour: curvature of the Universe

Houri Ziaeepour: But these extreme objects has a very small contribution in the total energy density.

You are welcome to continue discussion of this exciting topic in replies to this post