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The Ph-word                

                                            Particles, cosmology and everything

Hi <<First Name>>. Thanks for reading the seventeenth issue of this newsletter, which brings you the latest and greatest in physics!

I hope you are somewhere pleasant and cool. I am not. But last month I had the pleasure of ... astrotourism! I've been at an astronomy night at the observatory of the village Asea, probably the only community-run observatory in Greece. I talked about dark matter to anyone willing to listen and then sat back and took in the starry sky, both with the team's telescope and with naked eyes. It'd been years since I last saw a sky full of stars, which makes me wonder how many children grow up without ever seeing it and whether this affects their outlook. At least this is different for people in the "developing" world. (Could it mean that countries aspire to develop only to lose view of the stars? :0 :p)

I also had the joy of writing (in greek) about three things that I like considerably: science (the IgNobel prizes), Tokyo (one particularly personable neighbourhood) and theatre (a workshop on music in theatre by a great artist).
And, if you know about my adventures in solar physics, you might remember that I've worked on a model for predicting the sun's activity over long timescales. I now uploaded an article with the actual predictions about the next solar cycle on arxiv, the "preprint server" where articles live online before they hopefully make it to journals.

After this shameless intro let's jump to last month's physics... Which one of the usual suspects do you think made it this time? particles, cosmology or astrophysics?


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

Cosmic expansion overdrive

An old tension resurfaced in the summer quiet. The "SH0ES-Planck tension" was first in the news a year ago, and this is about two cosmology experiments measuring how fast the universe is expanding and finding somewhat different results. Now they are joined in the controversy by three more experiments (and increasingly facepalm-worthy names).

In brief, the SH0ES experiment ("Supernovae H0 for  the  Equation  of  State") looks at stars whose brightness we can tell exactly and measures how fast they move apart as space grows larger. The rate that it finds is 10% faster than that by Planck, the high-profile satellite telescope which analyzes the cosmic microwave background - the first and oldest light, that shone when the universe was only 400,000 years old.

Now, a couple of months ago the Dark Energy Survey popped up and took sides. This telescope spent the last five years looking at hundreds of millions of galaxies, in an effort to find out more about dark energy (codename for said expansion of universe accelerating with time). It also announced its own measurement of the current expansion rate - and it is in the ballpark of Planck's results.
But then, in July the H0LiCOW experiment ("H0 Lenses in COSMOGRAIL’s Wellspring" - just don't ask, okay?) came with results of its own - and agreeing with the SH0ES' numbers.
Only days apart, a heavyweight in cosmological observations helpfully decided to settle the matter. That was none other than the legendary Hubble telescope itself. It turns out that all this time its people had been preparing their own measurement. And, obligingly, its result falls between the numbers of the other two teams...

Some physicists (and particularly some media outlets) see adventure in this "tension". The conservative view however is that the distances and times involved in such measurements are large enough to justify uncertainties and miscalculations, and that the numbers might easily converge a few more telescopes down the road.
Serendipity

How long since you last handwrote a letter on paper and sent it by post? Wanna get old school for a cause?
If you (or somebody you know) are a scientist (in any field, and including university students) you could write "Letters to a Pre-scientist". That's a project that turns scientists into pen pals of kids in USA areas with high poverty. The idea being that once you know someone in science, it's easier to imagine yourself working in it in the future.
Applications for the coming school year are open for a few days more and you could take a peek here.
• A list of the previous Ph-issues.
A kind reminder of the list of previous mini-interviews and that they are all small gems.
If you are reading this and don't remember why / don't want to, please press "unsubscribe" below.
On the other hand, this is where one subscribes:
...Till next month.
Eleni
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www.chapette.net

Glimpses of the IBM office building in Amsterdam.
(from Blossom City Hotel, my photoblog)
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