Outstanding Problems in Cosmology Conclusions Outstanding Problems in Cosmology for the Next 20 Years ICGC 2015, IISER Mohali December 14-18, 2015

We do not know the physical nature of ~ 95% of the stuff that makes Dark Matter & Dark Energy We do not know the physical nature of ~ 95% of the stuff that makes our Universe

We do not know the physical nature of ~ 95% of the stuff that makes Dark Matter & Dark Energy We do not know the physical nature of ~ 95% of the stuff that makes our Universe Is there new type of energy (WIMP, Quintessence) or is it modified gravity (MOND, DGP)?

We do not know the physical nature of ~ 95% of the stuff that makes Dark Matter & Dark Energy We do not know the physical nature of ~ 95% of the stuff that makes our Universe Is there new type of energy (WIMP, Quintessence) or is it modified gravity (MOND, DGP)? A fundamental problem in Physics: the CC problem or what are the gravitational properties of the vacuum??

1) Are we sure it is inflation? Inflation & Early Universe 1) Are we sure it is inflation?

1) Are we sure it is inflation? Inflation & Early Universe 1) Are we sure it is inflation? No, but it looks very likely. A smoking gun would be to verify the consistency checks

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? Can we consistently embed inflation in high energy physics? HEP seems complicated so why vanilla inflation seems to emerge from the data (so far …)? UV sensitivity of inflation: problem or window of opportunity?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? How did inflation come to an end and can it be probed observationally?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? How did inflation come to an end and can it be probed observationally? How did inflation start? Is it eternal?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? How did inflation come to an end and can it be probed observationally? How did inflation start? Is it eternal? If we see non-minimal features, can we prove that they come to more complicated models of inflation?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? How did inflation come to an end and can it be probed observationally? How did inflation start? Is it eternal? If we see non-minimal features, can we proove that they come to more complicated models of inflation? K-inflation Multiple field inflation

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Who is the inflaton field? How did inflation come to an end and can it be probed observationally? How did inflation start? Is it eternal? If we see non-minimal features, can we proove that they come to more complicated models of inflation? 6) Can we learn something about Quantum Mechanics?

Are we sure it is inflation? Inflation & Early Universe Are we sure it is inflation? Which is the inflaton field? How did inflation come to an end and can it be probed observationally? How did inflation start? Is it eternal? If we see non-minimal features, can we proove that they come to more complicated models of inflation? 6) Can we learn something about Quantum Mechanics? Inflation is the only situation in Physics where you need GR, QM and you have high accuracy measurements (the closest situation would be the Colella-Overhauser-Werner –COW- experiment).

How to proceed? 1) B-modes

If r>0.01, we should know it in the coming 5 years How to proceed? 1) B-modes - We do not know where the signal is (~ SUSY in HEP) but feasible if r>0.001 If r>0.01, we should know it in the coming 5 years - Knowing r is very efficient for model selection Given that r<0.07, verifying the consistency check seems already hopeless … Maybe r<0.001 …

How to proceed? B-modes Non-Gaussianities

or feasible? If we do not find NG at this level, it is a revolution! How to proceed? B-modes Non-Gaussianities A priori, we know where the signal is (~ Higgs boson) but is it realistic or feasible? If we do not find NG at this level, it is a revolution! Maybe the NG is of order one … it would then point to more complicated models of inflation (multi field, features etc …)

Direct detection of inflationary gravitational waves How to proceed? B-modes Non-Gaussianities Direct detection of inflationary gravitational waves

Direct detection of inflationary gravitational waves How to proceed? B-modes Non-Gaussianities Direct detection of inflationary gravitational waves - Is it realistic …?? - Also important for reheating!

Direct detection of inflationary graviatational waves How to proceed? B-modes Non-Gaussianities Direct detection of inflationary graviatational waves Somehting else …??? To be discussed …