On inflation and the multiverse

[Note: in the following, and in the title, I have used the word multiverse a lot. When I do I am exclusively referring to this type of multiverse, which has, for example, been used to try to explain why the cosmological constant it so small. If you have any questions then please do ask them.]

About a week ago, Peter Coles, another cosmology blogger (who also happens to be my boss' boss' boss - or something), wrote a post expressing confusion about the association of inflation with the multiverse. His post was a reaction to a copy of a set of lectures posted on the arXiv by Alan Guth, one of the inventors of inflation (and discoverer of the name). Guth's lectures claimed, in title and abstract, that there is a very obvious link between inflation and a multiverse. Peter had some strong comments to make about this, including the assertion that at some points he's inclined to believe that any association between inflation and a multiverse is no different to a thought pattern of: quantum physics ---> woo ---> a multiverse!

I have some sympathy for Peter's frustration when people over-sell their articles/papers, and I would agree that inflation does not require a multiverse to exist, nor does inflation itself necessarily make a multiverse seem particularly likely/obvious. However, it is also true that, in a certain context, inflation and a multiverse are related. Put simply, through "eternal inflation", inflation provides a mechanism to create many Big Bangs. To get the sort of multiverse this post is about, these different Big Bangs need to have different laws of physics, which is not generic. However it can occur if the laws of physics depend on how inflation ends, in a way which I will describe below.

As with Peter though, I am unaware of any complete inflationary model that will generate a multiverse. We could both have a blindspot on this, but my understanding is that the situation is that people expect (or hope?) that complete models of inflation derived from string theory are likely to generate a multiverse for reasons that I will describe below.

Before that, you're probably wondering what this inflation thing is...

Inflation

The inflationary epoch is a (proposed - although the evidence for it is reasonably convincing) period in the past where the energy density of the universe was almost exactly constant and homogeneous (i.e. the same everywhere) and the expansion of the universe was accelerating. After this inflationary epoch ended, the expansion was decelerating (which isn't surprising given that gravity is normally attractive) and the universe gradually became less and less homogeneous, until it looked like it does today. We like inflation for all sorts of reasons, but for the purpose of this post, the preceding two sentences are all you need to know.

This is the "potential energy density" stored by a hypothetical inflationary field, \(\phi\). The x-axis is the value of \(\phi\). The y-axis is the energy density. The hatched region is where the conditions for "eternal inflation" would be satisfied.

Cubism. Realism. Sciencism.

Post-impressionist carcinoma.

This week's post from me will be relatively brief as I am currently on honeymoon, and although Shaun somehow manages to find time on his travels to blog about his conference experiences I doubt my new wife would be too happy if I did likewise! So, in lieu of my intended Human Machine series post (which will be coming early in the new year), I wanted to bring your attention to something wonderful going on at the Cell Picture Show.

The Cell Picture Show has appeared in the Trenches before (here and here), but this recent instalment is to me even more original and interesting than anything they've had before. The image above has two halves, both of which are strikingly reminiscent of Van Gogh's famous and beautiful Starry Night. They look like the product of some brilliant mind with an extraordinary mastery of colour and texture. In fact, the image on the left is a cross section of mouse skin containing basal skin carcinoma, with various components stained different colours and imaged using a fluorescence microscope. The image on the right is an artist's rendering of the same image using different coloured fabrics stitched together. This is part of Cell's exhibition 'Art Under the Microscope', in which images of biological samples are recreated into works of art by professional artists. The image above is just one example, but there are many others of similar standard available in the exhibition. The technical prowess of the researchers who obtained the original images is impressive, as are the aesthetic abilities of the artists who recreated them.

A fire-like network of neural stem cells in the human brain (left) and their artistic equivalent (right).

What I find so exciting about this exhibition is that it is redefining what can be the subject of art, and what can be the source of artistic inspiration. Nature has been inspiring artists for thousands of years, why should that be restricted to what we can see with our own eyes? We are now at a level of technology that we can begin to unveil many of the secrets that nature had previously been hiding from art. This should be exciting to both scientists and artists. Artists can be excited by the wealth of new subject matter that is beginning to open up to them, and scientists can be excited by the prospect of art adding to the ever-growing popularity and appreciation of science. Perhaps one day there will be great debates in artistic circles about new avant-garde artists who paint their proteins in a controversial way, much like the debates between the surrealists and romanticists on how to depict more macroscopic areas of nature. 

Although 'Art Under the Microscope' is a small exhibition, it nonetheless marks a growing trend in the use of science as inspiration for art. I sincerely hope that this continues as it will enrich both science and art, and help to blur the boundaries between them. Art has been very successful in entering many concious aspects of our daily lives, and we are the better for it. Science is still catching up in many regards, although to be fair it hasn't had all that long to make up the difference. If science were as exposed in the public conciousness and as everyday as art is, then I believe we would benefit similarly as we have from the ubiquity of art. The fusion of the two is a match made in heaven that is finally beginning to take hold. I look forward to the days when parks are adorned with pieces of science-based public art, and the spectrum of human endeavour is appreciated as single entity rather than as the separated, delineated pigeon holes of 'art' and 'science' as discrete subjects.

How does one measure the mass of a neutrino, using cosmology?

I'm going to tell you how, soon, humanity might measure the masses of neutrinos just by observing past events in the universe. I like this topic because it is one of the few situations in fundamental physics where a measurement of the greater universe might detect something about fundamental particles and/or their interactions, before we manage to measure it in a lab. Another example is the existence of dark matter; however the mass of dark matter will almost certainly be first measured in a lab. Perhaps with neutrinos it will go in the other direction?

What is a neutrino?

I guess that before telling you how to measure a neutrino's mass, it might be pertinent to tell you what a neutrino is and how we can know it has mass before we've measured that mass. Well...

When an atomic nucleus decays, the decay products we see are other nuclei, electrons and/or positrons. These visible products always carry less energy and momentum than the amount that the initial nucleus had. This suggests strongly that some unknown other particle is also being created in the decay and that we just can't see it. This hypothetical particle was dubbed the neutrino and when theories were developed for the force responsible for nuclear decays, the neutrino became an important part of them. And, eventually, neutrinos were detected directly. It took a while because neutrinos interact incredibly weakly, which means you need either a lot of neutrinos or a lot of transparent stuff for the neutrino to interact with (or both) before you will see them.

Initially, it was assumed that neutrinos are massless. They don't need to be massless, but for a long time there was no evidence that they did have mass, so the simplest assumption was that they didn't. There are three types of neutrinos: those emitted in interactions with electrons, those emitted in interactions with muons and those emitted in interactions with tau particles. If neutrinos were massless, then a neutrino emitted as an electron neutrino would always remain an electron neutrino. Similarly, a muon neutrino would always remain a muon neutrino. However, if neutrinos do have mass, then a neutrino emitted in an interaction with an electron will actually travel as a superposition of an electron neutrino, muon neutrino and tau neutrino. The net result being that this neutrino could be detected as a different type of neutrino. Therefore, a smoking gun thing to look for when determining whether neutrinos have mass is this characteristic signal whereby one type of neutrino appears to oscillate into another type of neutrino.

This effect was then seen and seen and seen again. Neutrinos appear to have mass. From the perspective of particle physics this is a bit weird. Neutrinos must have really small masses and it is unclear why these masses are so small. Unfortunately, this mechanism of neutrino oscillations doesn't directly give the masses of the neutrinos. Although, it can be used to measure the differences of the masses of the neutrinos, thus setting lower bounds on the possible masses of the neutrinos.

What has this got to do with cosmology?

The human machine: non-standard components

The previous post in this series can be found here.

In a previous post I alluded to the origins of mitochondria, the tiny chemical power plants found within all our cells. These hard-working machines are responsible for aerobic respiration, which is the way in which the vast, vast majority of the energy you use is released from the chemical energy in the food you eat. The way in which they do this is very cool, involving currents of electrons and protons in a manner very similar to standard battery. If you're interested in this then I direct you to my earlier post on this topic here, but in this post I will be discussing a rather odd thing about mitochondria: they're not in fact human...

What do I mean by this? Well, obviously they are, kind of, human since they're inside all of us, they're born with us and die with us, they don't wander off on their own to live an independent life elsewhere. Nonetheless, mitochondria are different to the rest of the machinery in our cells - they have their own genomes, they regulate their own replication, they make proteins their own unique way - in fact they closely resemble lifeforms that we might consider to be evolutionary polar opposites of ourselves: bacteria. That sounds pretty odd, right, that there might be bacteria living inside our cells that somehow want to help us by churning out energy for us to use? Seems pretty implausible, but there is a mountain of evidence supporting it.

If it barks like a bacterium...

Firstly, mitochondria do, kind of, look like bacteria. They are about the right size to be bacteria (0.5-1 micron in length) and have internal structures similar to many bacteria. The main difference is that mitochondria possess two membranes and no cell wall, whereas most bacteria for one membrane and a robust cell wall. The inner membrane of mitochondria is also far more ruffled than most bacteria, creating a much larger surface area - this is highly important for reasons that I'll come to!

Spot the difference: mitochondria on top, bacteria on the bottom. 

Being a foreigner in Finland (Intro)

The major goal of this blog has always been to try to make fundamental research accessible to interested non-specialists.

Another worthwhile thing to do, from the "Trenches of Discovery", is to describe what life is like in those trenches.

One of the most notable aspects of the postdoctoral research lifestyle is that you get to spend 2-3 years living in a series of places you might not otherwise have chosen to live. I've just finished three years living in Helsinki, the capital of Finland. I can say with pretty firm confidence that, prior to landing that job, I had never seriously considered the prospect that I might one day live in Finland. I had also never been there.

I've moved now. This is sad and exciting. I'm now employed by the University of Sussex. I've spent the six weeks between living in Finland and living in Britain, back in New Zealand on a kind of small time-frame sabbatical type thing, visiting Auckland University. I wish I could live in three places at once.

While it is still fresh, I want to write here what life is like (for a foreigner) in Finland.

Nature, culture, day-length, work-day-length, an individual's mental state, whether some of Jesus' achievements can be considered to be miraculous or not, just about everything about life in Finland, is dictated by the seasons. So, I've decided to serialise this thing into four pieces, about life in each season, starting, in the next post, with winter. The rest of this post will be a more general introduction.

What is Finland?

The Finnish coat of arms. The Nordic countries' coats of arms kind of satisfy their stereotypes. Here, the Finnish lion, drunk, and drooling, in a field of summer flowers, has unfortunately stabbed itself in the eye with a rather randomly human fourth limb.

Finland is a pretty remote place (though some others are more remote) and it doesn't try hard to be noticed on the world stage. Unless you approach Finland, it probably won't approach you. Therefore, for many people, the extent of their knowledge about Finland is that it is that cold, dark, place between Russia and Sweden. This is more or less what my knowledge of Finland was in 2009.

Finland is indeed the cold, dark place between Russia and Sweden. This is actually quite a good description of Finland in a historical context as well (on a couple of levels). It is only very recently (1917) that Finland became an independent nation, it previously having been a part of either Russia or Sweden, depending on the year. The national identity is, thus, very new compared to most of the rest of Europe. The Finnish language is, also, not a part of the Indo-European language family and as such has no close relative in all of Europe, except Estonian (a very close relative) and Hungarian (only recognisably related if you're a linguist). It's like a small pocket of something else, kind of European, but a little bit different, sitting up in the corner there on the map. Of course, people are people wherever they are, so the individual people of Finland are themselves no different to individual people in France, Fiji or the Falkland Islands, but the collective culture can differ.

Finland is very far North. Helsinki, the capital, despite being on the south coast of Finland, is still further north than the tip of mainland Britain. For those elsewhere than Europe, Finland has a similar latitude to Alaska, which is further north than all other U.S. states and most of the places that Canadian people live. For people from the better hemisphere, no permanent settlements exist as far south as Finland is north. Some bits of Finland are as far north as some bits of Antactica are south. This means that the longest nights in Helsinki are long (about 21 hours or so) and the longest day is even longer (about two months or so). I'll try to let that sink in later. The summer is nice and warm, without (normally) getting uncomfortably hot. And the winter is cold, though no colder in its extremes than a city in the U.S midwest. It's hard to express how much this significant difference in season affects everything in Finland, but hopefully I can get a bit of it across in the next few posts.

Finland is quite big (bigger than Britain and New Zealand, for example), but relatively unpopulated (just 5 million people in the whole country). This means there is a lot of space. Finland is also the nation that has the greatest proportion of its surface covered by water. This means that a huge chunk of Finland is lake, with most of the rest being forest. This sounds a bit like pointless trivia, but this large quantity of open space, and preponderance of lake and forest does have a strong influence on culture and frame of mind. There are no mountains, although I wouldn't quite compare Finland to Denmark or The Netherlands; there definitely are hills.

Finally, despite being somewhat remote geographically, and not a particularly boisterous nation, modern Finland is far from remote from the rest of the world, culturally. I didn't learn to speak Finnish. I found by far that the most difficult part about trying to learn Finnish was not the language itself, but the fact that almost every single Finn speaks English fluently. I used to joke that the second most spoken language in Finland is Finnish. It didn't really go down that well.

What's to come...

In Finland, when someone is awarded a doctorate, they customarily buy a top-hat and a sword. That is a real sword. Hopefully  Finnish PhD graduates do a little better than that lion.

Experiencing Finland needs to be done (at least) twice for each season. You can appreciate moments more when you know what has lead to that moment and what that moment is leading to. I've found this particularly true for autumn, typically the most bittersweet of seasons anywhere. A Finnish autumn, in the moment, is delightful. There is a charge in the air, that, if you arrive for the first time in autumn, you notice right away. I didn't understand its origin the first time, but I came to associate it with an atmosphere left over from the vibrancy of a Finnish summer. And, the true poignancy of a Finnish autumn can only be experienced when you fully understood what the beginning of winter is like in Finland.

The darkness brought by the beginning of winter in Finland is oppressive. There is no point in hiding that. The second half of winter in Finland is wonderful, and easily one of my favourite things I've experienced, anywhere. But the beginning of winter can only be described as profoundly oppressive. This isn't necessarily an entirely bad thing. Witnessing anything extreme adds a sense of thrill and perspective. A Finnish winter definitely aids in quiet reflection. But it is only thrilling because it is extreme. Once the darkness breaks, however, winter turns into an almost literal wonderland, at least for a kiwi. You can walk on the sea. You can commute to work on skis (and some colleagues did). In one Finnish winter you see snow take thousands of forms and... apologies for geeking out... through these forms mimic many different kinds of rock, be they sedimentary, volcanic, granite, sand, or otherwise.

"Spring", in Finland, doesn't exist. Or, at least, it does, but what the rest of the world calls spring, happens for about fifteen minutes, at around 4pm, sometime late in May. Instead of spring, there is a long, ordinary length season, that would be more appropriately labelled "the thaw". This season is bleak and barren. Whatever got buried, under the snow, at the beginning of winter, be it leaves, grass, dog poo, bikes, cars, or even people, will emerge five months later, in April. The sterility of the cold and the snow passes, but what it leaves behind is the dead husk of the previous summer. None of any part of nature (plant, animal or human) will believe winter is over until it can be absolutely sure, so the city sits and it waits, continuing to wait long after the last snow has melted, and the tension builds.

Until summer arrives explosively. I'm only a little bit joking; you can see the grass grow in Finland in June if you sit and watch it. I've never been anywhere that feels more vibrant and full of life than Finland in the summer. August, in Helsinki, is my favourite thing in the world. I spent a significant chunk of each of my three Finnish Augusts wishing I'd had the chance to experience a Finnish August as a barefoot, lakeside, tree-climbing, berry-picking, lake-swimming, night-time book reading, eight year old. As it stands, I just got to be a sandal-wearing, seaside, tree-appreciating, berry-eating, sea-swimming, night-time book reading, 28 year old, which is still pretty good.

And then autumnn comes again. Nature, and the rest of Finland, prepares for rest, and the intensity of the summer gradually dissipates into winter.

[More in later posts...]

Follow @just_shaun

Two doctorates, a wedding, a full-time job and a move overseas

Regular readers who knew we actually had a schedule here might have been wondering what's happened with the posts. If you're one of these people, then you might be happy to know that things will return to normal (well, 2013 normal) from next Monday.

Posts disappeared because all three of the contributors to the blog have had significant life events in August/September. James is now literally a couple of weeks away from submitting his doctoral thesis (see you on the other side, dude) after which he will be literally a couple of weeks away from getting married. Michelle has been balancing being a full-time PhD student with being a full-time museum curator all year. And I've just moved from Finland to the UK, via six weeks in New Zealand.

As my excuses are the weakest, I'll be the first back to blogging. This will be next Monday. Thanks for hanging around.

Working hard or hardly working?

"Life grants nothing to us mortals without hard work." So said Horace, the Roman lyric poet, over two millennia ago and little has changed since. I am currently one to attest to that sentiment as I am in the middle of writing up my PhD thesis and have accordingly developed the peculiar mania that grips many students at this stage in their degree where non-thesis pursuits become shamefully wasteful or even patently corrosive of your time! So, I'm afraid that this week's post from me is just a brief one, and the long-promised 'human machine' edition on stem cells is being pushed back yet again, apologies.

In light of this sudden idiopathic workaholism that overtaken me, it seems appropriate that my post this week be on the subject of how hard scientists work. Coming into science I knew that the pay is generally crap, and it's not particularly glamorous, and you have to look for a new job every three years until you settle down with your own cosy lab somewhere - but at least it's a fairly nice lifestyle, right? Well yes and no. I love the academic lifestyle - it's the right mix of individual freedom and motivating challenges, by which I mean that it isn't too stressful but isn't boring either. That has been my experience (present situation excluded), but a recent report from the University of Nottingham suggests that I may have been one of the lucky ones, or perhaps that things are going to worsen for me! 

The report (available here) looked at the working hours of conservation scientists in several countries by analysing the time and day of 25,000 publication submissions to the journal Biological Conservation. It's true that this is not, perhaps, the most reliable indicator of general working patterns since people tend to put in extra hours in the run-up to publication, but the results are still intriguing nonetheless. The long and the short of their findings are that scientists, basically, work pretty damn hard (well, conservation biologists at least). They observed that 16% of manuscripts were submitted late at night, and 12% were submitted at weekends, and that the proportion of work submitted outside of normal hours has been increasing ~5% each year. This paints a fairly bleak picture for the future if working hours are going to stretch further and further into personal time.

Perhaps unsurprisingly, the study also found significant differences in working habits between different countries. The countries whose scientists seem to work the most unsociable hours are Japan and Mexico, who seem to work late (~30% manuscripts submitted out of hours on weekdays), as well as China and India, who work weekends a lot (up to 40% submitted at weekends). The most relaxed scientists were found in Belgium and Norway, who like their weekends off (~5% submitted on weekends), as well as South Africa and Finland, who go home at 5 (less than 10% submitted after hours on weekdays) - thus explaining Shaun's abrupt move to Helsinki three years ago! British and American scientists were about average in their working habits.

So what makes many scientists so busy, and why do they stick at it for often quite poor salaries? Well the combined research, teaching, reviewing, and administrative duties of senior scientists puts a big strain on their time. The authors of this investigation warn that this can may be having a negative impact on the quality of the science produced, as well as the happiness of the researchers themselves.  Dr Ahimsa Campos-Arceiz, who led the study, reflects:

 "We call for academic institutions to remember that good science requires time to read and think and over-stressed scientists are likely to be less productive overall. We also recommend that peer-review activities are included as part of the academic job description and considered in staff performance evaluations. At the end of the day, working on this paper has been an opportunity to reflect about our own behaviour and priorities. Next time I go to Bali, I will spend more time swimming and talking with my wife and less working on manuscripts."

Why so many scientists are willing to put up with the current situation is perhaps the more informative question. People become scientists often because of a burning curiosity that they must fulfil, and the realisation of that goal is its own reward. In many ways, academic science is an indulgence that most other professions wouldn't tolerate. Researchers are, by and large, able to investigate whatever they're interested in, in whatever way they see fit. Clearly, dead-end research is eventually weeded out by funding bodies (*all hail the funding bodies*) but generally it's fairly flexible and if you're interested in something and stick in science then there's a good chance you'll end up working on it. As well as this, there is the feeling that you are contributing to something bigger than yourself. Research never disappears, it will outlive you and become your legacy once you're just a memory. This is the same sensation that artists must get when creating their masterpiece, or writers have as they pen their latest novel. Moreover, if your research is useful then it can have ramifications far beyond anything you could achieve in most other jobs, but even if it's not then you're still helping to take one more step along the path of human progress. This is why people chose to be scientists and work unreasonable hours for a lot less money than an investment banker, and it's why I would always encourage anyone who is interesting in entering science as a career.

So, Horace was right, life gives you nothing without hard work, but then if that work is intoxicating enough then life begins to mean nothing without it either.