Archive for Planck ESA

Nature After Planck…

Posted in Maynooth, The Universe and Stuff with tags , , , , , , on July 24, 2018 by telescoper

After last week’s short update about the last tranche of papers from the European Space Agency’s Planck Mission it’s time for another short update about a piece in Nature (by David Castelvecchi) that explains how researchers are moving to smaller projects studying different aspects of the cosmic microwave background.

In the spirit of gratuitous self-promotion I should also mention that there’s a little quote from me in that piece. My comment was hardly profound, but at least it gets Maynooth University a name check…

Much of Davide’s piece echoes discussions that were going on at the meeting I attended in India  last October, but things have moved on quite a bit since then at least as far as space experiments are concerned. In particular, the proposed Japanese mission Litebird has been shortlisted for consideration, though we will have to wait until next year (2019) at the earliest to see if it will be selected. An Indian mission, CMB-Bharat, has also emerged as a contender.

While the end of Planck closes one chapter on CMB research, several others will open. These are likely to focus on polarization, gravitational lensing and on cosmic reionization rather than refining the basic cosmological parameters still further.

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Planck’s Last Papers

Posted in The Universe and Stuff with tags , , , , on July 17, 2018 by telescoper

Well, they’ve been a little while coming but just today I heard that the final set of a dozen papers from the European Space Agency’s Planck mission are now available. You can find the latest ones, along with the all the others, here.

This final `Legacy’ set of papers is sure to be a vital resource for many years to come and I can hear in my mind’s ear the sound of cosmologists all around the globe scurrying to download them!

I’m not sure when I’ll get time to read these papers, so if anyone finds any interesting nuggets therein please feel free to comment below!

The IKEA Universe

Posted in Biographical, The Universe and Stuff with tags , , , on January 29, 2018 by telescoper

I heard yesterday the sad news of Ingvar Kamprad, the founder of Swedish furniture chain IKEA.  People can be very snobbish about IKEA, but its emphasis on affordable design has been a boon for people on low incomes for many years. When I was an impoverished postdoc living in London I used it a lot, especially their Billy bookcases. I also have a very sturdy Omar in my bedroom…

I remember years ago  that while shopping in the IKEA at Neasden I discovered that they were running a competition, for which entrants had to complete the sentence:

I shop at IKEA because…

My entry completed it thus:

I shop at IKEA because it’s as cheap as fuck.

I didn’t win.

But I digress. Not many people are aware that IKEA also furnishes  important insights into modern cosmology, so I’ll try to explain here. I’ve blogged before about the current state of cosmology, but it’s probably a good idea to give a quick reminder before going any further. We have a standard cosmological model, known as the concordance cosmology, which accounts for most relevant observations in a pretty convincing way and is based on the idea that the Universe began with a Big Bang.  However, there are a few things about this model that are curious, to say the least.

First, there is the spatial geometry of the Universe. According to Einstein’s general theory of relativity, universes come in three basic shapes: closed, open and flat. These are illustrated to the right. The flat space has “normal” geometry in which the interior angles of a triangle add up to 180 degrees. In a closed space the sum of the angles is greater than 180 degrees, and  in an open space it is less. Of course the space we live in is three-dimensional but the pictures show two-dimensional surfaces.

But you get the idea.

The point is that the flat space is very special. The two curved spaces are much more general because they can be described by a parameter called their curvature which could in principle take any value (either positive for a closed space, or negative for an open space). In other words the sphere at the top could have any radius from very small (large curvature) to very large (small curvature). Likewise with the “saddle” representing an open space. The flat space must have exactly zero curvature. There are many ways to be curved, but only one way to be flat.

Yet, as near as dammit, our Universe appears to be flat. So why, with all the other options theoretically available to it, did the Universe decide to choose the most special one, which also happens in my opinion to be also the most boring?

Then there is the way the Universe is put together. In order to be flat there must be an exact balance between the energy contained in the expansion of the Universe (positive kinetic energy) and the energy involved in the gravitational interactions between everything in it (negative potential energy). In general relativity, you see, the curvature relates to the total amount of energy.

On the left you can see the breakdown of the various components involved in the standard model with the whole pie representing a flat Universe. You see there’s a vary strange mixture dominated by dark energy (which we don’t understand) and dark matter (which we don’t understand). The bit we understand a little bit better (because we can sometimes see it directly) is only 5% of the whole thing. The proportions do look very peculiar.

And then finally, there is the issue that I have ablogged about (here and there) previously, which is why the Universe appears to be a bit lop-sided and asymmetrical when we’d like it to be a bit more aesthetically pleasing.

All these curiosities are naturally accounted for in my New Theory of the Universe, which asserts that the Divine Creator actually bought  the entire Cosmos  in IKEA.

This hypothesis immediately explains why the Universe is flat. Absolutely everything in IKEA comes in flat packs. Curvature is not allowed.

But this is not the only success of my theory. When God got home He obviously opened the flat pack, found the instructions and read the dreaded words “EASY SELF-ASSEMBLY”. Even the omnipotent would struggle to follow the bizarre set of cartoons and diagrams that accompany even the simplest IKEA furniture. The result is therefore predictable: strange pieces that don’t seem to fit together, bits left over whose purpose is not at all clear, and an overall appearance that is not at all like one would have expected.

It’s clear  where the lop-sidedness comes in too. Probably some of the parts were left out so the whole thing isn’t  held together properly and is probably completely unstable. This sort of thing happens all the time with IKEA stuff. And why is it you can never find the right size Allen Key to sort it out?

So there you have it. My new Theory of the Universe. Some details need to be worked out, but it is as good an explanation of these issues as I have heard. I claim my Nobel Prize.

If anything will ever get me another trip to Sweden, this will…

Planck Time

Posted in The Universe and Stuff with tags , , , , , , on February 13, 2012 by telescoper

Only time for a quickie today, as I have a busy afternoon in store at a meeting in the Graduate College (zzz…). Today there has been a press conference in Bologna about latest results from the ESA experiment, Planck. Here’s a picture taken at the press conference by roving reporter astrophysicist Mike Peel.

I gave a talk in that room once, actually, although there weren’t any press people there on that occasion.

Although it will be some time still before the full cosmological results from Planck are released to the public (and researchers outside the Planck Consortium), the press conference covered a number of new and interesting discoveries, particularly about our own Galaxy. You can read about them at the  ESA Planck website here and on the UK Planck site (hosted at Cardiff University) here.

Among the results are beautiful maps of microwave emission from cold molecular gas (e.g.  carbon monoxide) from sources inside the Milky Way:

Planck wasn’t specifically designed to detect CO emission, but it’s part of the “foreground” radiation that must be understood and modelled on the way to extracting cosmological information from the results.

Another exciting item is the Galactic Haze that emanates from the central regions of the Milky Way, which you can see in this picture poking out from behind the “mask” that is used to blank out emission from the Galactic Plane (i.e. the disk of our Galaxy).

The origin of this haze, which appears to be consistent with synchrotron radiation but with quite a hard spectrum, is not known and is the topic of much discussion in the astrophysics community.

For more information, see the main Planck site or, with more technical details, here.