Dark Lightning

Artist’s conception of the Earth’s magnetic field (in pink)
funneling positrons (in yellow) and sending them to the Fermi
Gamma-ray Space Telescope where they were observed.

The Fermi Gamma-ray Space Telescope is an Earth-orbiting space observatory that is being used to perform high-energy gamma-ray astronomy. Launched in June of 2008, this telescope is probing the cosmos for gamma rays and high-energy events. And while it is finding many sources for these events, such as supernova explosions and distant, supermassive black holes from other galaxies, it has also found an unlikely source closer to home.
   In 2009, the telescope was hit by a stream of high-energy positrons—the antimatter version of electrons—coming from a thunderstorm on Earth. 100 trillion positrons had been funneled into a tight pulse by the Earth’s magnetic field and hurled straight to the observatory at nearly the speed of light. To put that number into perspective, it’s more than what hits the Earth’s atmosphere from all other cosmic sources combined. Somehow, antimatter had been produced in the clouds above Earth and the best theory we have to explain it is dark lightning.
   Earth-orbiting satellites have been observing terrestrial gamma ray flashes (TGFs) from thunderstorms as far back as 1994. And it is also known that gamma-rays at the right energy can produce electron-positron pairs.
   Normal lightning occurs when unbalanced electrostatic charges in the atmosphere trigger a massive discharge between a cloud and the ground or between two clouds. A light flash traces the path of the charged particles which heat the air to 30,000°C, nearly six times hotter than the surface of the Sun. 

Feynman diagram for a gamma ray photon
decaying into an electron-positron pair.

   Dark lighting may seem crazy, but there is mounting evidence that it’s real. Like ordinary lightning, dark lightning also tries to neutralize the unbalanced electric fields in a thunderstorm. Under the right conditions, the thunderstorm creates a powerful avalanche of electrons shooting away from Earth at nearly the speed of light. The electrons collide with air molecules in the atmosphere to produce gamma rays. Next, the gamma ray energy transforms into electron-positron particle pairs. Further collisions between these particles and other air molecules creates a repeating cycle—a self-generating, self-sustaining particle accelerator. Once the loop gets started, it can discharge the thundercloud as fast as lightning. And because the cascading electrons and positrons generate more gamma rays than visible light, the process is practically invisible to the human eye. 
   Researchers once thought the gamma ray flashes from thunderstorms were a weird by-product of ordinary lightning. Now many think it is dark lightning instead. The gamma ray burst monitor onboard the Fermi Gamma-ray Space Telescope is perfectly suited to record these flashes and new data processing techniques have improved the burst monitor’s performance. In mid-2010, a testing a mode was initiated which allows for the detection of faint gamma ray flashes that had previously gone undetected. Now Fermi should be able to catch nearly 1,000 flashes each year. With an abundance of new data, researches hope to gain new insights on the mysteries of dark lightning.

A Hundred Authors Against Einstein

The book “Hundert Autoren Gegen Einstein”
(A Hundred Authors Against Einstein) was
published in 1931.

The old adage “there is strength in numbers” is not always true, especially when it comes to science. Science is not advanced through polls or consensus. Observation and experimental evidence is what matters. Thankfully, being in the minority does not necessarily mean one is wrong.
   Case in point: The book Hundert Autoren Gegen Einstein (A Hundred Authors Against Einstein), a collection of various criticisms of Einstein’s theory of relativity. Published in 1931, it contains short essays from 28 authors, and published excerpts from 19 more. The balance was a list of 53 people who were also opposed to relativity for various reasons.
   The book was not a reaction against Einstein from the physics community—only one physicist had contributed. Nor was it supported by the younger generation—only two of the contributors were much younger than Einstein. It was a dying cry from the old guard of science that felt left behind by the new physics and incompetent because they didn’t know what to do with it. Before Einstein published his work, Newton’s theories were gospel among the scientific community. Einstein had the temerity to use space and time as a way to think of our Universe, not just an a priori condition in which we lived.

Before relativity, space was thought
to be best represented by Euclidean
geometry (above). Relativity requires
the extra dimension of time be
considered when representing
space (below).

   Many had a philosophic objection to relativity, based on Immanuel Kant’s assertion that space was intuitive and could not be perceived by observation or experience. Newton’s view that space was absolute and existed independently of what it contained, as defined by Euclidean geometry, had ruled for over two centuries unchallenged. 
   When asked about the book, Einstein retorted by saying “Why 100 authors? If I were wrong, then one would have been enough!”
   Einstein’s fame from the success of his ground-breaking theories had created a backlash. Even thought the book contains no outright anti-Semitism, six of the authors were either anti-Semitic and/or Nazi sympathizers. The rising Nazi movement denounced Einstein, calling relativity “Jewish physics”. Einstein left Germany in 1932 out of fear for his safety and never returned. The Nazis had put a price on his head, publishing his photo on the cover of one of their magazines with the caption “Not Yet Hanged”. Einstein moved to the United States, settling at the Institute for Advanced Study at Princeton in New Jersey.
   Of all the contributors to the book, the one that I found the most distressing was Emanuel Lasker. Lasker was a German mathematician, philosopher and the World Chess Champion for an incredible 27 years. Einstein and Lasker had met through a mutual friend in Berlin in 1927, and over the course of many walks together they exchanged opinions about a variety of topics. According to Einstein it was a somewhat lopsided exchange, in that Einstein received more than he gave. Nonetheless, they developed a close friendship. Given that Lasker was also Jewish and had been forced to leave Germany after the Nazis took power, it’s disheartening that he had gone against his friend, but apparently it didn’t bother Einstein.
   To Lasker, the notion that no matter how fast you travelled the observed speed of that light was constant was ridiculous. Einstein claimed to have “never considered in detail, either in writing or in our conversations, Emanuel Lasker’s critical essay on the theory of relativity” and thought of Lasker as a Renaissance man and uniquely independent. Many years later, when asked to write the forward to a posthumous biography on Lasker, Einstein was forced to address this reproach to relativity, saying that “…chess playing of a master ties him to the game, fetters his mind and shapes it to a certain extent so that his internal freedom and ease, no matter how strong he is, must inevitably be affected”. In other words, Lasker—while brilliant—lacked the capacity to think outside the box.

A Fallacy, Naturally

Volcanic eruptions must be good, right?

If I could reverse one trend in the year ahead, it would be the use of the word "natural" in advertising. Our legal system spent too many resources in 2012 wrestling with whether products like Sobe® lifewater® or Dreyer's ice cream could legally claim to be "all natural" (the lifewater suite was dismissed, the Dreyer's suit was allowed to continue).
   Even if we could agree on what is natural, all-natural, unnatural or not-in-the-least-bit-natural, nothing can be ascertained from such information. British philosopher Julian Baggini says "There is no factual reason to suppose that what is natural is good (or at least better) and what is unnatural is bad (or at least worse)."
   The idea that chemicals are artificial and necessarily bad is absurd. Everything including our own bodies are made of the same basic building blocks. Living things, both plant and animal, require the same ~30 elements to live and be healthy. We would be much better served by reading the calorie and fat content of that ice cream instead of trying to figure out if the chocolate is natural.
   Most biologists denounce an appeal to nature (also known as a naturalistic fallacy) because they want to describe the natural world honestly, without extracting morals about how we ought to behave. Canadian psychologist Steven Pinker explains "If birds and beasts engage in adultery, infanticide, cannibalism, it must be OK. The moralistic fallacy is that what is good is found in nature. It lies behind the bad science in nature-documentary voiceovers: lions are mercy-killers of the weak and sick, mice feel no pain when cats eat them, dung beetles recycle dung to benefit the ecosystem and so on. It also lies behind the romantic belief that humans cannot harbor desires to kill, rape, lie, or steal because that would be too depressing or reactionary." I could not agree more.
   Maybe I'm just more sensitive to crass marketing than most—I don't know. It could be because I work in the industry, so bad marketing hits a nerve with me. Or maybe it just bothers me that these sort of tactics work so well—a sign of a generally uneducated public, at least as far as science is concerned. I borrow from the Irish comedian Dara O Briain: "Science knows it doesn't know everything; otherwise, it'd stop. But just because science doesn't know everything doesn't mean you can fill in the gaps with whatever fairy tale most appeals to you." 
   Don't even get me started on what marketers have done with the word "organic".

Understanding the Big Bang

An artist’s concept illustrating the expansion of
the Universe after the Big Bang.

The term Big Bang was originally coined by the English astronomer Fred Hoyle in an attempt to help listeners to a radio program that he was a guest on understand the difference between it and the popular Steady State theory of which he was a proponent. The Steady State theory had been around since 1920 and proposes that matter in the Universe was being continually created, and had existed pretty much as it does today for all time. 
   In 1931, the Belgian physicist Georges Lemaître first suggested the evidence for the expansion of the Universe, if projected back in time, meant that all the mass of the Universe was at some point concentrated into a single “Primeval Atom”. Einstein initially refused to accept the concept, telling Lemaître that “Your math is correct, but your physics is abominable.” It would take Einstein another four years to embrace the theory.
   Simply put, The Big Bang theory states that because space is expanding, the Universe must have been much denser in the past. Einstein’s theory of gravity lets us run time backwards to calculate the density of the Universe billions of years ago. As a result we know that the observable Universe must have expanded from an extremely dense and hot state about 13.7 billion years ago.
   During the Big Bang, matter did not explode into space from a point. The Big Bang was an expansion of space itself that filled all of space with energy right from the beginning. 

Timeline of the Universe.

   Evidence indicates only that the early universe was extremely dense, but not necessarily extremely small. Even though the observable portion of the Universe was once packed into an incredibly small volume, it was not surrounded by empty space—it was surrounded by more matter and energy which is now beyond the observable Universe. This leads to an amazing little-known conclusion: if the whole Universe is infinitely large, then it was always infinitely large, even during the Big Bang.
   Current evidence also tells us that the Universe is either infinitely large, or else is so large that we cannot detect its curvature from what we can observe—similar to how we can not tell that the Earth is round by looking at our back yard.
   The observational evidence for the Big Bang is overwhelming and is known as the Four Pillars of Big Bang Cosmology: Hubble expansion as measured through the redshifts of distant galaxies, the discovery in 1965 of cosmic microwave background radiation, the abundance of hydrogen and helium in proportions predicted to have been produced during the Big Bang, and the formation of galaxies and large-scale structure such as galactic superclusters.
   But the Big Bang is not the whole story—its details are a subject of intense research. The Big Bang theory says nothing about how the universe came into being in the first place—it just assumes that energy, space and time already existed. And because current description of physical laws do not yet apply to such extremes of nature, we may never know what actually happened during the Big Bang. 

Space: The Misunderstood Frontier

According to Einstein’s theory of general relativity,
gravitational attraction between masses results from
their warping of space and time.

This week I am going to deal with some popular misconceptions about space and the Universe in general. Next week I will tackle the Big Bang theory.
   First off, we must realize that when we look out in space we are looking back in time. It takes a long time for the light from distant objects in the Universe to reach us. Light from the Sun takes eight minutes to reach us, and light from nearby stars takes years. Distant galaxies are seen as they looked millions or even billions of years ago. Galaxies extend out far beyond what we can see today, but how far no one knows. Because the Universe has been evolving and expanding over time, most of the light from the distant reaches of the Universe has not yet had time to reach us. 
   As far as we can tell, there is no edge to the Universe. Galaxies extend as far as we can detect in every direction with no sign of diminishing. Even though galaxies extend much further than we can see, we don’t know if the Universe is infinite. So when a galaxy is described as being near the edge of the Universe, what is really meant is that it is near the edge of the observable Universe.
   Until Einstein showed that space has structure, astronomers thought of space as just the emptiness that contains matter. But Einstein showed, through his general theory of relativity, that space is flexible and can be warped. Now when we talk about the expansion of the Universe, we are referring to the stretching of space itself—not just galaxies moving apart through space.
   The notion that space is expanding was predicted by Einstein’s theory of gravitation which describes a simple but universal relationship between matter, space and time. It was a prediction that Einstein initially couldn’t embrace. He modified his theory by adding a term to achieve a static Universe that he called a cosmological constant. Later, after observational evidence by Edwin Hubble indicated that the Universe was indeed expanding, Einstein abandoned his constant calling it his biggest blunder.
   Today, we know that not only is the Universe expanding, but that it is expanding at an ever-accelerating rate. Cosmologists use the term “dark energy” to explain this mysterious energy that Einstein had embraced, then discarded. The best explanation we have today for dark energy is that it is a vacuum energy associated with virtual particles—quantum fluctuations which produce particle pairs that blink into existence and then annihilate in a times pan too short to measure. This happens everywhere, throughout the Universe. But there is a big problem with this theory—vacuum energy is far too weak to account for the acceleration of the expansion of the Universe. One thing is clear—discovering the properties of space remains one of the core problems of modern science.

Ten Great Moments in Science

This week’s quiz will test your knowledge of science history. As you read these ten great moments in science, try to match them up with the year in which they occurred.
   I’m starting something new this week: a ladder competition. If you submit your name along with your answers I will keep a running tally of the top ten scores over time and update the results weekly. See if you have what it takes to make the top ten!

Here are the years to choose from for the ten items below. Each year is only used once.: 1543, 1665, 1687, 1775, 1859, 1905, 1909, 1919, 1923 and 1928.

1) Newton publishes Principia, describing the three fundamental laws of motion forming the basics of classical mechanics. ______

2) Hans Geiger and Ernest Marsden, under the direction of Ernest Rutherford, perform the gold foil experiment which probes the structure of the atom demonstrating the existence of the atomic nucleus. ______

Charles Darwin

3) Darwin’s On the Origin of Species is published and becomes the foundation for evolutionary biology. ______




4) Joseph Priestley discovers oxygen. ______

5) Albert Einstein’s Miracle Year, where he publishes four articles that contribute to the foundation of modern physics, covering the photoelectric effect, Brownian motion, special relativity and mass/energy equivalence. ______

Nicolaus Copernicus

6) Nicolaus Copernicus describes a heliocentric solar system with the Earth and other planets revolving around the Sun, challenging the common perception at the time that the Earth was the center of the universe—as had been the assumption since the time of the Greeks. ______

7) Alexander Fleming discovers penicillin, the world’s first antibiotic. ______

8) Arthur Eddington observes the bending of light during a total solar eclipse, confirming Einstein’s theory of general relativity. ______

9) Robert Hooke coins the term “cell” to describe the building blocks of life that he saw and described in his book Micrographia. ______

10) Edwin Hubble discovers that Andromeda is a galaxy, proving that the Milky Way is only one of hundreds of billions of galaxies in the visible universe. ______

Did Einstein Really Say That?

It is very popular, nowadays, to strengthen an argument by quoting Einstein. The problem is that many of the quotes attributed to Einstein were never actually his. Some were him repeating a quote of another individual, but many others seem to be completely made up. Einstein has become the source to a treasure trove of phony quotes, largely because the internet has enabled us to share so much without sourcing anything.
   Einstein did not humiliate an atheist professor as an undergraduate, but Google returns over 61,000 hits on the subject. Nor did he trade places with his chauffeur and let the driver give his lecture instead. Recently, Einstein has been resurrected to say that if all the bees disappeared mankind would be extinct in four years. A classic case of a quote being invented and attributed to someone famous to give it extra credence. Einstein has been used by both sides of the debate on religion.
   So, how well do YOU know what Einstein said? Take our quiz and find out—you might be surprised.