This is a weekly post by Nidhal Guessoum (see his earlier posts here). Nidhal is an astrophysicist and Professor of Physics at American University of Sharjah
2010 is almost over, and this will be my last post of the year, so let me take part in that tradition of “Top 10 stories” which most publications, print or online, carry at the end of each year.
The following list, though ranked from 10 to 1 is very subjective and personal. Indeed, I don’t claim any substantial knowledge in many fields of science to appreciate and compare developments from various disciplines, and I am obviously partial (by training and by inclination) toward Astronomy and Physics, so my list is automatically biased. Still, as you will see below, there are a few non-Astro/Physics topics I have found important, and – a little spoiler – my “Number One” story of the year is from Biology…
One more caveat before we start the tour: some of the following developments have yet to be confirmed, so they come with a “TBC” label. They may potentially be of great importance, and they drew my (and others’) attention when they were announced, but they may turn out to be erroneous after additional scrutiny. That’s the nature of Science. Hence the list below reflects my immediate impression of developments in 2010 rather than their long-term importance or impact.
So here goes.
10. Our Sun has stolen many comets from other stars
Do you know how many comets there are in our solar system? Billions and billions, as Carl Sagan would say (I know – he never used that expression, but it was such a neat characterization of his style). No seriously, and reality is often more striking than fiction, the number of comets in our solar system is estimated at almost a trillion! Do you know how much volume they occupy? They extend about half-way to the nearest star, that is about 100,000 times farther than we are from the Sun, so they occupy a volume about 10 billion times larger than the 8 planets occupy! And so, as my students invariably do at this point, one wonders how they are still kept in by the Sun’s gravity.
It turns out, from work published this year, that a substantial fraction of those comets, at least the outer ones (in the Oort Cloud) came from matter which originally belonged to other stars that used to be in the same cluster as our Sun; our bright and strong guy just pulled them in… The conclusion was reached by a simulation of the dynamics of such a star cluster and the formation of its objects (planets, comets, etc.). Fascinating…
9. Biggest and coolest stars of all
You may not have known that stars cannot be smaller than a certain size (about one tenth of the Sun’s mass) or larger than a maximum limit (until now thought to be about 150 solar masses). The lower limit is simply because you need a minimum amount of pressure to raise the temperature in the core to above some 10 million degrees in order for fusion reactions to take place between hydrogen nuclei (otherwise you don’t have a star). The higher limit is due to the instability that too much mass will produce, thus preventing the formation of a star. Well, it turns out that bigger stars exist: one was found with a mass of 265 solar masses, which forces astrophysicists to review their models.
Also, when a blob of mass is too small to form a star, it may become a “brown dwarf”, the color being produced by the heat generated from the gravitational energy. The smallest bona fide stars (with masses larger than one tenth of a solar mass) have surface temperatures of about 2,000 degrees (compared to 6,000 for the Sun). Brown dwarfs are much cooler (little energy radiated), and a record breaker was found this year with a surface temperature of barely 200 degrees C!
The universe will not cease to amaze us, even with objects we thought we knew so well. Speaking of such…
8. O Moon, we hardly knew ye…
The Moon is at least a hundred times closer to us than any other object in the heavens. So close, we’ve reached out and touched it, several times, and brought back hundreds of kilograms of rocks from it. And yet, we keep discovering new, important things about it…
For one, water was found in much greater quantities than previously believed. How much? As much as can be found in all of North America’s Great Lakes! Of course, there are no lakes of that sort; the water is all spread out in minuscule amounts through the rocks.
Secondly, the Moon is now believed to be shrinking! This was concluded from images showing cliffy scarps all across the lunar surface, which are thought to be the result of contractions from when the Moon’s core lost heat and contracted. How much contraction, you ask? A few hundred meters… Over the past 4.5 billion years? Yes, I know, not very impressive. Still, interesting, no?
7. Early Life on Earth: a Moroccan makes a historic discovery
Regular readers of Irtiqa may remember that I wrote at some length about this TBC discovery last July. It made the cover of Nature, but it didn’t produce the kind of blogosphere hurricane that the Arsenic-loving bacteria story had a few weeks ago (widely criticized since). Still, in France at least, where the main team of scientists, led by the Moroccan Abderrazak El-Albani, works. As I reported then, Le Monde then wrote: "a new history of life -- biology textbooks would have to be rewritten..." Why? Because the hundreds of multi-cellular life fossils that had been found (in Gabon) were dated to 2.1 billion years ago, while the earliest such complex life form had previously been only 670 million years old.
This is a potentially “historic” discovery for its obvious implications, but as always we shall await further work, by this team and others, both on these samples and other ones elsewhere.
6. Baby picture of the universe
A new map of the universe, from almost 13.7 billion years ago, was produced and released by the European Space Agency this past July. It shows the universe at its baby age of 300,000 years (0.002 per cent of its present age, or the first day in the life of a human being). In the image (below), which was produced by the Planck space telescope (launched just a year before), one can see some tiny lumps of gas, those which would many millions of years later produce galaxies and clusters of galaxies.
The present picture is still not “clean” enough to be used for cosmological purposes, being tainted by local clouds of gas and dust from our own galaxy. Once those are removed, one should be able to get a deeper understanding of the state of the universe at those earliest times. Such a perfect picture is not expected to be released before another year or two, so for now we’ll content ourselves with this pretty one.
5. Super-Earths (looking for smaller and smaller planets)
The search for an Earth-like and habitable planet continues. So far, much progress has been made, but the goal, though perhaps near, has not been reached yet. Smaller and smaller planets are now found, and with Kepler (the NASA space telescope launched last year and dedicated to this task) now fully operational, more and more impressive discoveries are being made.
In January, an exoplanet with a mass four times that of Earth was found by the 10-meter Keck I telescope atop Hawaii’s Mauna Kea. It was then the second smallest exoplanet to ever be found (among some 400); it orbits its star in only four days, and lies some 80 light-years from here.
Then, in June, Kepler started to produce more impressive discoveries: researchers revealed that 700 candidate exoplanets were extracted from their preliminary data, including some that could be Earth-size. But no confirmation yet.
In August, however, HARPS, the High Accuracy Radial-Velocity Planet Searcher at the La Silla Observatory in Chile, announced the discovery of a planetary system with at least 5, and possibly 7, planets around a star some 125 light-years from here (the present record is 5).
And finally, also in August, the Kepler team announced the discovery of a super Earth of 1.5 times the diameter of Earth, which would make its mass about 3.5 times that of Earth; it orbits its star every 1.6 Earth days, and so its temperature would be around 1000 degrees, if not more (depending on its rotation rate and atmosphere).
Clearly, we do not have anything resembling Earth at this stage, but we are fast approaching the discovery of Earth-size planets. Whether any of those will be habitable is another (complicated) story.
4. Early diagnosis for Alzheimer’s
My grandmother died of Alzheimer’s disease earlier this year. Her mind had slowly deteriorated over the past several years, until the last stage where she could not recognize almost anyone… It’s a very taxing illness, for the patient and everyone around him/her. And that is why I, and many people, pray for a treatment, or at least an early diagnosis technique, to come soon.
An important development occurred this year when researchers reported that two tools had been developed, with – so far – a 100 % success rate of early detection. In the first technique, the patient is injected with a radioactive dye, which will color a plaque in the brain (seen by radio-imaging), thus indicating an early development of Alzheimer’s. The second technique takes cerebral fluid from the patient’s spine and analyzed for the presence of “markers” (some specific proteins) related to the disease.
These tools will now allow researchers to try new drugs on early patients and study their effectiveness over longer time periods, thus largely increasing the chances of the discovery of the best treatment.
3. New ancestors and relatives
The story of human evolution has not been fully uncovered, far from that. This year, new important pieces of the puzzle were discovered. And I’m not even counting Ardi, which was presented to the world in 2009…
First there was that discovery in South Africa of an “ancestor” of ours that seemed to have “jumbled” parts: a head the size of an Australopithecus africanus, the pelvis of a Homo erectus, and the arms of a Miocene ape. Those all came from a 12-year-old boy (named Karabo) who lived 1.9 million years ago, and who may represent an important bridge between the Australopithecus and the Homo species (walking upright the same way humans do, etc.).
Then, new cousins of ours, called the Denisovans, actually closer to the Neanderthals, were introduced to us (“nice to meet you!”). They lived in Asia from roughly 400,000 to 50,000 years ago. All we have found (so far) of the Denisovans (in a Siberian cave) are a broken finger bone and a tooth. That was enough for researchers to construct the entire genome of the Denisovans, the analysis of which (published last week in Nature) showed the following amazing story: half a million years ago, the parent tribe of both the Neanderthals and the Denisovans emerged from Africa and split, the first ones heading west toward Europe, the others going East to Asia; then some 50,000 years ago, the Denisovans encountered humans coming out of Africa along the southern coast of Asia and interbred with them, so that the DNA of people in New Guinea today contains about 5 % of the Denisovans’…
I am sure the human evolution saga will be further refined in the future with more stunning discoveries…
2. How matter defeated antimatter
This is another story I had commented on, or at least on some aspects of it, back in May.
I had then explained that matter (or particles) was (were) actually created in the early universe from “pure” energy, which can be converted to particles and antiparticles. The problem is that first, the matter and the antimatter must come out in equal amounts, and secondly they all will sooner or later meet their nemeses and “annihilate” each other back to “pure energy”. So how come there is matter today, and so little antimatter?
The physicists answer that at some point in the process of formation of matter (the above pair creation, followed by some decays of one particle or another), the symmetry gets “broken” and some extra matter (1 particle for every 30 million pairs) is produced and left over. And particle physicists have proposed various models of this symmetry-breaking process, but none have had their predictions confirmed by experiment. Until now – maybe!
Researchers at Fermilab’s Tevatron accelerator have looked at 8 years of data (high-energy collisions between particles) and say they have found a previously unobserved symmetry violation that could be just enough to explain “our existence” (that of all matter). Obviously, this will need to be confirmed, so this is another TBC case, and indeed new experiments are being planned both at Fermilab and at the Large Hadron Collider in Switzerland to see if the effect can be confirmed. Stay tuned.
1. Bacterium with a synthetic DNA
This scientific breakthrough was overhyped and often mis-presented as “artificial life”, yet I still think it was the most important development of the year. In May, Craig Venter, the human genome pioneer, announced that a pre-existing bacterium functioned perfectly when its DNA was replaced by a new, synthetic, though closely related one; it replicated according to its new genome and lived normally after the “operation”. Venter referred to it as “the first self-replicating species… whose parent [its designer] is a computer.” The achievement took 15 years of work and $40 million of resources.
Reactions ranged from wild enthusiasm (at the prospects of an entirely artificial cell that may be made “soon” and its implications with respect to ethics and human worldviews, and also in regard to its probable benefits) to strong criticism (over potential dangers from mistakes that could escape into our environment and the ethics of newly acquired god powers). President Obama referred the matter to the Presidential Commission for the Study of Bioethical Issues, asking for a report on the implications of this work.
Venter is already pursuing the commercial benefits of his line of work. In October he started a company that will collaborate with Novartis (the pharmaceutical giant) to create new synthetic flu vaccines. Also, Synthetic Genomics, the company he created in 2005, is working on synthetic fuel-producing microbes in a $300 million project with ExxonMobil…