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The Ph-word                

                                            Particles, cosmology and everything

Hi <<First Name>>. Thanks for reading the t h i r t e e n t h issue of this newsletter!

By a happy coincidence it's on this historic day for science that one year of Ph-issues is completed...
I started this "blog without the blog" as I thought that all the newsletters I get from designers, coaches, cryptoprogrammers and pole dancers are fun, and why should they be reserved for such hipsters.
My hope for the future is that these emails become more meaningful and less annoying with time! (And that if you like something in here you introduce your physics-curious entourage to them.)
Lastly, to celebrate my doing something consistently for a whole year I put together a page (because for some people celebrating is a euphemism for extra work) with all the interviews with science travel tips given to the Ph-word by a bunch of fab physicists. One of the things changed in this newsletter recently is not having them interviews anymore due to the sizeable chunk of time needed for their planning. But every single one that we've had is a small gem and can be enjoyed here.

eleni@chapette.net
March '19: The latest in ph-word

Last month we had two pieces of news, both connected to events of exactly one year ago and both involving the behaviour of physical components ... whatever that means!

Charm CP-violation

It was time for Les Rencontres de Moriond again, the particle physics conference-cum-excuse-for-skiing. (Seriously, that's where inspiration is supposed to hit).
The main takeaway from the conference was, once more, that the Standard Model of elementary particles keeps getting confirmed. But also like last year, the only new news came from the experiment which is turning out to be the sliest one in the Large Hadron Collider: the LHCb.
The LHCb crowd was done analyzing the data from all these years' proton smashing and announced that they observed for the first time CP-violating decays involving the charm quark. Now, hold on. It's bullet time:

- Take an object and make a copy of it, only with everything reversed like in a mirror; you'd expect it to work and play in the same way as the original. This sounds so intuitive (I guess) that even elementary particles comply.
- Now take a particle and its anti-particle, that is change its electric charge and a few other such numbers that we'd better not get into right now. It will still indulge us by behaving in the same way as the original except for the opposite charges.
- Given the above, what would one expect from an anti-particle that is also reversed? Why, to behave like the particle that we started with. (Where behaving usually refers to emitting away smaller particles after a while, i.e. its "decays".)
- All this symmetric behaviour is known as the CP-symmetry - for charge and parity.
- Now, since the swinging '60s it is known that some decays sometimes break this simple rule... These decays involve strange quarks and bottom quarks (these are their given names, okay?).
- This is as baffling as it might sound. Actually it's one of the most mysterious facts involving particles. And it's known as CP-violation.
- The LHCb experiment saw CP-violation now also involving the charm quarks.
- What they actually measured was the difference in decays of composite particles that are made up of charm quarks among others. And the small difference was clearly there.

The violation is not just a riddle but possibly also related to why the universe is made out of matter instead of antimatter. In any case any new piece in the CP-puzzle is always welcome.

Darkmatterless galaxies

A year ago a galaxy was found to not contain any dark matter ("DM" to friends) but, as we were writing, some re-checking would be good. The re-checking took place, by pointing more telescopes at it and still seeing it rotating in a way that suggests no presence of DM (which, incidentally, isn't the same as antimatter!).
The plot thickened as a second such galaxy seems to be found. They both have an uncharacteristically low number of stars, which might or might not be relevant.
Nobody's sure yet if DM is really matter or something exotic, like gravity misbehaving in ways we haven't foreseen. But these findings support the case for actual matter - otherwise every galaxy should show the same misbehaviour of gravity. (Also, they add to another recent such indication, namely DM appearing more pushed outwards in galaxies with more stars formed in their centres.)
The kickin' link
Check now if in two days' time one of the "world space parties" takes place somewhere near you. (12th April 1961 was when Yuri Gagarin became the first human to travel in space.)
Serendipity

Do you wonder if scientists ever place bets on their favourite theories? Of course they do. A lot. Actually two types of bets have been so frequent that each deserves its own “serendipity” column: bets about supersymmetry (see next month) and bets placed by Stephen Hawking.

It all started in 1975, with Hawking betting against the other celebrated black holes expert, Kip Thorne, that the curious object Cygnus X-1, strong source of X-rays, is not a black hole. In 1990 it was generally established that it is, with the depressing outcome that one of today’s top scientists won a subscription to Penthouse (to his credit Hawking would have got an obscure satirical magazine instead, the Private Eye). This was a bet for safety, a small source of joy in case black holes turned out to not really exist. [Last minute edit: Which we know very emphatically since a few hours ago to not be the case.]

In 1991 Hawking bet against Thorne and theorist John Preskill that “singularities”, the space-time anomalies that black holes are, cannot exist outside of the latter, aka be “naked”. In 1997 he agreed that “a technicality” permits this in special cases and the bet was rephrased to cover the general case.

In 1997 Hawking and Thorne now bet against Preskill that information is lost irretrievably in black holes, one of the main postulates that had made Hawking famous. In 2004 he accepted that a property of string theory would allow for the opposite and presented Preskill with a baseball encyclopedia. Thorne has not conceded the bet yet (buying himself some more integrity in this case, if you asked me, since string theory is only hypothetical so far).

It’s not known when the bet against the Higgs boson being discovered was made (but it wouldn’t be surprising if that was in 2005, seeing the pattern in the dates of the previous ones). In any case it was settled with its discovery in 2012, when Hawking lost an extra hundred dollars to theorist and low-hanging fruit harvester Gordon Kane.
Previous Ph-issues are found here.
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...Till next month.
Eleni
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www.chapette.net

Celebrating Jikji, the first-ever printed book; train station at Cheongju, S.Korea.
from my photoblog Blossom City Hotel)
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