Tag Archives: cosmology

Talk at Planetarium

Vigyan Prasar in association with Nehru Planetarium is organizing popular lecture at 10:00 AM tomorrow 23 August 2016 at Sky theater at planetarium. Interested people can join the programme.

The Speaker: Akshat Singhal,
Marie-Curie Fellow – Europe’s most competitive and prestigious awards, Early Stage Researcher (ESR) fellowship within the project Grawiton – European Marie Curie Action INT at Gran Sasso Science Institute in L’Aquila, Italy.

Title of Talk: “The sound of black holes”


Recently mankind has detected first gravitational waves as predicted by Albert Einstein 100 years with his theory of General Relativity. This discovery was considered as one of important discovery in the centuary. One of the most challenging experiment physicists ever undertook, measuring the change in length smaller than 1/1000th of a diameter of proton over 4km. We will discuss how many challenges are overcome and how did we achieve this endeavor.

The Big Bang’s Lithium Problem

Whoever said that with the discovery of the Higgs boson, the field of cosmology suddenly became dull and everything of significance is known known.
Enter Lithium, a particle physicist’s worst nemesis. The reason why this simple element is such a big problem is that we know how stellar hydrogen fuses to become Lithium
in Big bang like conditions. We’ve verified this experimentally. However the amount of Lithium found in stars and the observable universe is much much lesser.

Scientists at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) studied how much lithium forms under Big Bang conditions for the first time and determined that the theoretical calculations were indeed correct. The phenomena under which Lithium is created has a rather fancy name called “primordial nucleosynthesis”. The things scientists do for getting grant money 😛

The experiment was performed in an underground lab called the Laboratory for Underground Nuclear Astrophysics (LUNA), shielded by cosmic particles using a lead barrier.
These are the extreme setup conditions needed to get correct results.

The question is, if the theory works what’s happening out there. Why do stars contain much lesser quantity that what we should have seen.

For the advanced reader See

M. Anders et al. (2014), First Direct Measurement of the 2H(a,?)6Li Cross Section at Big Bang Energies and the Primordial Lithium Problem. Physical Review Letters 113, 042501. DOI 10.1103/PhysRevLett.113.042501

Physicists Look for Evidence of time travellers on the internet

Physicists R. Nemiroff (of APOD fame) and his student Teresa Wilson, recently published their results of a grand internet search to look for evidence of time travelers. In a nutshell they were looking for ‘time traveler activity’ over the internet, say a timer traveler used his time machine to move back in time and say…send an email, or put information online about world events that just happened way before it actually did. Time travel to the future is allowed by special relativity, however there is much debate if we can actually go back in time.

The search as you may have expected didn’t turn out much …. but made for a pretty good story.

To read more you can download their preprint paper here