The Ph-word                

                                            Particles, cosmology and everything

Hi <<First Name>>. Thanks for reading the eighth issue of my newsletter! Today we have things happening from the tiniest to the largest, mostly involving lots of gravity, all topped with our travel tips.

In mid-October I visited charming Larisa, central Greece, for speaking at the pre-fest of the local NASA Space Apps Challenge. The Apps Challenge is a worldwide hackathon for anyone wishing to think about space problems; this is the second hackathon-like astro-event I've been to in the last couple of months and based on the experience I really like it that the approach is spreading. Oh, and I spoke about the star closest to earth. (You know, the one found at eight light-minutes away.)
Also, my quest for finding, ehm, innovative ways to carry out research goes on but let's leave this for a future issue!
Now jump straight to the good stuff - and if you feel like saying hi do it with the line just below.
October '18: The latest in ph-word

Improved electron EDM limit

Elementary particles are not looked for at only giant smashing machines. Nature is very subtle at such small scales, but then so are we.

So, how else can the tiniest building blocks of the world be probed? By looking very closely at other particles. And why is it so? Because particles keep being generated and perishing from and back to vacuum the whole time, affecting other particles while they do so. (By the way this last sentence is totally true and no brain-altering substances were involved.)

Now, there are several theories about physics and particles beyond the ones we've found and some of them would have a very straightforward effect on the behaviour of good old electrons: they would give electrons an electric dipole moment, i.e. they'd change the distribution of electric charge across an electron.
You are justified if this sounds slightly fishy to you, since for everybody an electron is kind of a synonym for the electric charge itself! ...But this is exactly why looking for a possible asymmetry of its charge is a big deal.

To cut the story short, the ACME experiment has just put limits on the possible electron charge asymmetry by a lot, i.e. not seeing any, cropping out several theoretical models without using any particle collider. (What they used is a few molecules and measuring how their electrons spin and topple. Yes, of course it is harder than I make it sound.) ACME is on its theory-weeding mission for half a decade now and will probably do so for several more years to come.

Black holes for dark matter

For the purpose of this discussion, let's combine three things. First, dark matter. The unseen and unknown stuff filling up most of the galaxies, one of the biggest mysteries in physics today.
Second, primordial black holes. Many people have hypothesized that in the extreme conditions when the universe was young, black holes might have formed abundantly just because of the gravitational pressure at various points in the hydrogen clouds. And if they have indeed, then they might make up dark matter.
Third, gravitational lensing. The fact that light is attracted by heavy celestial bodies and changes its path. So, for instance, astronomers see multiplied idols of distant galaxies because they are actually hidden from us behind other galaxies that bend their light!

Now let's combine them, should we? A search looked at how often supernovae get gravitationally lensed, without any obvious object causing the lensing. If this happened, then primordial black holes would be the culprit, and we could tell how many of them float around in our galaxy more or less.
Unfortunately, no lensing of supernovae was seen; which limits the possible number and size of primordial holes below that needed to account for dark matter.

And I say "unfortunately" because primordial black holes have always been my favourite explanation for dark matter. Still, studies of such an ambitious scope usually need a second confirmation, so one can still hope a little bit...

Arcane galaxy clusters 

In other news, superclusters of galaxies bind together thousands of (duh) galaxies. Proto-superclusters did the same, only at a time much closer to the big bang than to today. And the most ancient known proto-supercluster was just announced and named Hyperion. It's found at a humbling 11.5 million years ago and its age is actually told by how fast it's moving away from us - as a result of the universe's expansion.

On the way to Mercury 

Finally, the Euro-Japanese craft BepiColombo got off for its date with Mercury in 2025.
Amazingly, nearby Mercury has so far been visited by only two crafts, legendary Mariner 10 in 1974 and Messenger in 2011. The main reason being that without tricky calculations they'd most probably fall into the sun instead of staying in orbit - and indeed BepiColombo will do several sophisticated slingshot flybys using the gravity of Earth, Venus and Mercury until captured into the latter's orbit.
The kickin' link
Master glassmaker Josh Simpson isn't only inspired by space to create otherworlds and megaplanets, but he also has ambitious terrestrial plans. In his Infinity Project he's been handing out mini glass planets to earthlings who promise to hide them in various corners on this planet, in an effort to baffle future archaeologists!
Earth travel tips... 

Sushant Raut is a theoretical physicist hailing from Bombay and now working in Daejeon, South Korea, where he researches the mysterious neutrino particles (and organizes the monthly event "Science on Tap").
- Sushant, what is your suggestion to tourists who are also science fans for things to do in Bombay?
I was born and raised in Bombay (now Mumbai), India, which has a lot of historical and cultural tourist attractions. For those who love science, I highly recommend the Nehru Planetarium and Nehru Science Centre. The planetarium has many installations on astronomy, and there are daily shows in the planetarium dome. Nehru Science Centre has multiple floors of interactive exhibits on physics, chemistry, biology, mathematics and computer science. It is a place for kids (and curious adults) to get a hands-on experience of the principles of science -- whether it is conservation of momentum, magnetic levitation, human sensory responses, probability distributions, binary numbers, etc. Another fun activity is to visit the Sanjay Gandhi National Park, a vast natural forest within the city limits with a lot of biodiversity in terms of mammals, birds, insects, reptiles and plants. Visiting these places during my childhood definitely played a big role in encouraging me to study science and take it up as a career.

- Will you share a few words about a cool project or discovery that you've worked on?

The India-based Neutrino Observatory (INO) is expected to be built in an underground cavern in southern India. Its main aim is to measure the oscillations of atmospheric neutrinos in order to determine which of the three neutrinos in nature is the lightest. The USP of the INO detector is that it will be made of magnetized iron, which will allow us to observe neutrinos and anti-neutrinos separately.
During my early post-doc days, I performed simulations to understand the capabilities of this experiment to not only measure the neutrino mass ordering, but also other parameters that affect neutrino oscillations. Our results found that INO data in conjunction with beam neutrino experiments could help to measure 'leptonic CP violation', which can explain the abundance of matter over antimatter in the Universe.

- Many thanks!
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...Till next month.

Parthenon and a modern church through an ancient gate; are today's religions tomorrow's tourist spots?
(from my photoblog Blossom City Hotel)
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