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.