science

Is Our Universe a Giant Simulation?

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The physics paper of the week is “Constraints on the Universe as a Numerical Simulation” by Silas Beane and company at University of Bonn in Germany. Their fundamental question: is the universe just a giant simulation, in which we are all puppets? From their abstract:

Observable consequences of the hypothesis that the observed universe is a numerical simulation performed on a cubic space-time lattice or grid are explored. The simulation scenario is first motivated by extrapolating current trends in computational resource requirements for lattice QCD into the future. Using the historical development of lattice gauge theory technology as a guide, we assume that our universe is an early numerical simulation with unimproved Wilson fermion discretization and investigate potentially-observable consequences. Among the observables that are considered are the muon g-2 and the current differences between determinations of alpha, but the most stringent bound on the inverse lattice spacing of the universe, b^(-1) >~ 10^(11) GeV, is derived from the high-energy cut off of the cosmic ray spectrum. The numerical simulation scenario could reveal itself in the distributions of the highest energy cosmic rays exhibiting a degree of rotational symmetry breaking that reflects the structure of the underlying lattice.

Could you fathom the possibility that our entire cosmos is running on a vastly powerful computer? I cannot.

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(via Technology Review)

Reddit’s Mind Blowing Sentences

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This is a great thread on Reddit: “What is the most mind-blowing sentence you can think of?”

To start things off:

No one is going to remember your memories.

This one is my favorite:

The difference between billion and trillion is equivalent to the difference between your lifetime and the entirety of human history.

This rings close to home:

“When you do things right, people won’t be sure you’ve done anything at all.”

On exploration:

We know more about the surface of the moon than we do about the ocean floor.

I like this explanation of pi:

Pi is an infinite, nonrepeating decimal – meaning that every possible number combination exists somewhere in pi. Converted into ASCII text, somewhere in that infinite string of digits is thename of every person you will ever love, the date, time, and manner of your death, and the answers to all the great questions of the universe.

What would be your mind-blowing sentence?

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(via SciencePopularis)

Fake Science 101: Confessions of a Fake Scientist

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Phil Edwards, the man behind the Fake Science blog and author of Fake Science 101, writes a confession:

The most difficult part about being a fake scientist is telling people what you do for a living. It’s hard enough with friends, family members, and Internal Revenue Service auditors, but small talk is even rockier terrain. One summer on a flight from Chicago to San Francisco, I found myself stammering in my airplane seat when the subject of occupations came up. Five-hour flights can create some awkward situations, but this one seemed particularly perilous. I had to admit I was a fake scientist. And I was sitting next to a real one.

Though actual science has remained opaque to me during my tenure as a fake scientist, I have learned a bit about real scientists. When I started encountering them, I took an anthropological pleasure in analyzing their quirks and humor. (I’m so nonscientific that even when I’m pretending to be a scientist, it’s a social scientist.) I should note that my data on this group isn’t statistically significant or peer reviewed—I am, after all, the type of scholar who spends most of his time Photoshopping babies drinking from beakers. Still, I’ve gleaned a bit about scientists from having conversations, responding to Facebook comments, and reading enthusiastic tweets.

I learned quickly that real scientists—the people I’d satirized with crisp lab coats and serious lab-goggle-covered faces—could be incredibly silly. I should have known that from my friends in scientific fields, but it remained shocking to see lauded pros act gleefully absurd. When I created a fake gossip magazine about scientists, I never anticipated that Mike Brown would tweet back. (He’s an astronomer whose Twitter name, @plutokiller, should give you an idea how he feels about his role in declassifying Pluto as a planet.) That silliness drew scientists to my site, and their intelligence only enhanced it.

The Amazon book reviews are particularly good:

“This book is so good, I almost don’t mind that I died penniless!”–Nikola Tesla

“For the last time, I am not the physicist Stephen Hawking. I’m Steve Hawking and I’m a business administrator in Ohio. I will not read your book.”–Stephen Hawking, Says He’s Not The Physicist, But Who Knows?

“Thank you for contacting the offices of Neil Armstrong. The office cannot respond to all letters, but thank you for your interest. Please enjoy the enclosed color photograph.”–Neil Armstrong, First Man On the Moon

Click to read the rest of the confession, in which Phil Edwards discovers something new about bears going on knife hunts.

A Brief History of Sleep

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From a very interesting Wall Street Journal piece on sleep, we learn some history about how humans used to get two sleeping chunks at night:

So why is sleep, which seems so simple, becoming so problematic? Much of the problem can be traced to the revolutionary device that’s probably hanging above your head right now: the light bulb. Before this electrically illuminated age, our ancestors slept in two distinct chunks each night. The so-called first sleep took place not long after the sun went down and lasted until a little after midnight. A person would then wake up for an hour or so before heading back to the so-called second sleep.

It was a fact of life that was once as common as breakfast—and one which might have remained forgotten had it not been for the research of a Virginia Tech history professor named A. Roger Ekirch, who spent nearly 20 years in the 1980s and ’90s investigating the history of the night. As Prof. Ekirch leafed through documents ranging from property records to primers on how to spot a ghost, he kept noticing strange references to sleep. In “The Canterbury Tales,” for instance, one of the characters in “The Squire’s Tale” wakes up in the early morning following her “first sleep” and then goes back to bed. A 15th-century medical book, meanwhile, advised readers to spend their “first sleep” on the right side and after that to lie on their left. A cleric in England wrote that the time between the first and second sleep was the best time for serious study.

The time between the two bouts of sleep was a natural and expected part of the night, and depending on your needs, was spent praying, reading, contemplating your dreams or having sex. The last one was perhaps the most popular. A noted 16th-century French physician named Laurent Joubert concluded that plowmen, artisans and others who worked with their hands were able to conceive more children because they waited until after their first sleep, when their energy was replenished, to make love.

The phrase is “segmented sleep” and it can be reproduced:

Studies show that this type of sleep is so ingrained in our nature that it will reappear if given a chance. Experimental subjects sequestered from artificial lights have tended to ease into this rhythm. What’s more, cultures without artificial light still sleep this way. In the 1960s, anthropologists studying the Tiv culture in central Nigeria found that group members not only practiced segmented sleep, but also used roughly the same terms to describe it.

Fascinating.

15-Year-Old Improves Pancreatic Cancer Test

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Maryland teenager Jack Andraka (featured in the video above) isn’t old enough to drive yet, but he’s just pioneered a new, improved test for diagnosing pancreatic cancer that is 90% accurate, 400 times more sensitive, and 26,000 times less expensive than existing methods.

When Andraka had solidified ideas for his novel paper sensor, he wrote out his procedure, timeline, and budget, and emailed 200 professors at research institutes. He got 199 rejections and one acceptance from Johns Hopkins: “If you send out enough emails, someone’s going to say yes.” Andraka was recently awarded the grand prize at the Intel International Science and Engineering Fair for his groundbreaking discoveries.

Persistence is the key.

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(via Make)

Riding the Plasma Wave

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A cloud forms as an F/A-18 Hornet aircraft speeds up to supersonic speed. Aircraft flying this fast push air up to the very limits of its speed, forming what’s called a bow shock in front of them.

Lynn Wilson who is a space plasma physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, writes the following:

Throughout the universe more than 99 percent of matter looks nothing like what’s on Earth. Instead of materials we can touch and see, instead of motions we intuitively expect like a ball rolling down a hill, or a cup that sits still on a table, most of the universe is governed by rules that react more obviously to such things as magnetic force or electrical charge. It would be as if your cup was magnetized, perhaps attracted to a metal ceiling above, and instead of resting, it floats up, hovering somewhere in the air, balanced between the upward force and the pull of gravity below.

This material that pervades the universe, making up the stars and our sun, and also – far less densely, of course – the vast interstellar spaces in between, is called plasma. Plasmas are similar to gases, and indeed are made of familiar stuff such as hydrogen, helium, and even heavier elements like iron, but each particle carries electrical charge and the particles tend to move together as they do in a fluid. Understanding the way the plasma moves under the combined laws of motion we know on Earth and the less intuitive (to most Earthlings, at least) electromagnetic forces, lies at the heart of understanding the events that spur giant explosions on the sun as well as changes in Earth’s own magnetic environment – the magnetosphere.

Understanding this mysterious world of plasma, however, is not easy. With its complex rules of motion, the study of plasmas is rife with minute details to be teased out.

Which particles are moving, what is the source of energy for the motion, how does a moving wave interact with the particles themselves, do the wave fields rotate to the right or to the left – all of these get classified.

Wilson is the first author of a paper in Geophysical Research Letters that was published on April 25, 2012. Using data from the WAVES instrument on NASA’s Wind mission, he and his colleagues have discovered evidence for a type of plasma wave moving faster than theory predicted it could move. The research suggests that a different process than expected, electrical instabilities in the plasma, may be driving the waves. This offers scientists another tool to understand how heat and energy can be transported through plasma.

For the study, Wilson examined coronal mass ejections (CMEs) – clouds of solar material that burst off the sun and travel through space — that move so much faster than the background solar wind that they create shock waves. These shock waves are similar to those produced by a supersonic jet when it moves faster than the speed of sound in our atmosphere.

Read more here. Photo credit: NASA/Goddard.

Aerographite: The New Lightest Material in the World

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A team of German scientists from the Technical University of Hamburg and University of Kiel has developed a new carbon-nanotube-based material called Aerographite that’s the lightest material in the world. It’s density is only 0.2mg per cubic centimeter. To put that into perspective: styrofoam is 75 times denser.

Aerographite is made of mostly air–99.99 percent, to be exact–along with carbon nanotubes. The scientists created the material by growing an interlinking chain of carbon nanotubes onto a zinc oxide template:

To create the material, researchers started with a zinc oxide in powder form and heated it up to 900 degrees Celsius, which transformed it into a crystalline form. From this material the scientists made a kind of pill. In it, the zinc-oxide formed micro and nano structues, called tetrapods. These interweave and construct a stable entity of particles that form the porous pill. The tetrapods produced the network that is the basis for Aerographite. In a next step, the pill is positioned into the reactor for chemical vapour deposition at TUHH and heated up to 760 degrees Celsius. 

The lightest material I’ve ever held is aerogel, which I described in this post. By comparison, aerographite is at least ten times less dense than aerogel.

Why Supermarket Tomatoes Taste Like Cardboard

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It’s no secret that the mass-produced tomatoes we buy at a typical grocery store tend to taste like cardboard. Now researchers have discovered one reason why: a genetic mutation, common in store-bought tomatoes, that reduces the amount of sugar and other tasty compounds in the fruit.

Mass-produced tomato varieties carrying this genetic change are light green all over before they ripen. Tomatoes without the mutation — including heirloom and most small-farm tomatoes — have dark-green tops before they ripen. There is also a significant difference in flavor between the two types of tomatoes, but researchers had not previously known the two traits had the same root cause.

The study authors set out to pin down the genetic change that makes tomatoes lose their dark-green top. They focused their attention on two genes — GLK1 and GLK2 — both known to be crucial for harvesting energy from sunlight in plant leaves.

They found that GLK2 is active in fruit as well as leaves — but that in uniformly colored tomatoes, it is inactivated.

Adding back an active GLK2 gene to bland, commercial-style tomatoes through genetic engineering created tomatoes that had the heirloom-style dark-green hue. The darker green comes from greater numbers of structures called chloroplasts that harvest energy from sunlight.

The harvested energy is stored as starches, which are converted to sugars when the tomatoes ripen.

The vast majority — 70% to 80% — of the sugar in tomatoes travels to the fruit from the leaves of the plant. But the remaining amount of sugar is produced in the fruit. This contribution is largely wiped out in uniform, commercial-style tomatoes — and thus they won’t be as sweet.

For the science nerds, here is the paper’s abstract:

Modern tomato (Solanum lycopersicum) varieties are bred for uniform ripening (u) light green fruit phenotypes to facilitate harvests of evenly ripened fruit. U encodes a Golden 2-like (GLK) transcription factor,SlGLK2, which determines chlorophyll accumulation and distribution in developing fruit. In tomato, two GLKs—SlGLK1 and SlGLK2—are expressed in leaves, but only SlGLK2 is expressed in fruit. Expressing GLKsincreased the chlorophyll content of fruit, whereas SlGLK2 suppression recapitulated the u mutant phenotype. GLK overexpression enhanced fruit photosynthesis gene expression and chloroplast development, leading to elevated carbohydrates and carotenoids in ripe fruit. SlGLK2 influences photosynthesis in developing fruit, contributing to mature fruit characteristics and suggesting that selection of u inadvertently compromised ripe fruit quality in exchange for desirable production traits.

It’s no wonder that tomatoes you can grow in your backyard taste that much better.

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(via Los Angeles Times)

The End of Moore’s Law

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Theoretical physicist Michio Kaku argues that the end of Moore’s Law is coming sooner than later:

Years ago, we physicists predicted the end of Moore’s Law that says a computer power doubles every 18 months.  But we also, on the other hand, proposed a positive program.  Perhaps molecular computers, quantum computers can takeover when silicon power is exhausted.  But then the question is, what’s the timeframe?  What is a realistic scenario for the next coming years?  

Well, first of all, in about ten years or so, we will see the collapse of Moore’s Law.  In fact, already, already we see a slowing down of Moore’s Law.  Computer power simply cannot maintain its rapid exponential rise using standard silicon technology.  Intel Corporation has admitted this.  In fact, Intel Corporation is now going to three-dimensional chips, chips that compute not just flatly in two dimensions but in the third dimension.  But there are problems with that.  The two basic problems are heat and leakage.  That’s the reason why the age of silicon will eventually come to a close.  No one knows when, but as I mentioned we already now can see the slowing down of Moore’s Law, and in ten years it could flatten out completely.  So what is the problem?  The problem is that a Pentium chip today has a layer almost down to 20 atoms across, 20 atoms across.  When that layer gets down to about 5 atoms across, it’s all over.  You have two effects.  Heat–the heat generated will be so intense that the chip will melt.  You can literally fry an egg on top of the chip, and the chip itself begins to disintegrate  And second of all, leakage–you don’t know where the electron is anymore.  The quantum theory takes over.  The Heisenberg Uncertainty Principle says you don’t know where that electron is anymore, meaning it could be outside the wire, outside the Pentium chip, or inside the Pentium chip.  So there is an ultimate limit set by the laws of thermal dynamics and set by the laws of quantum mechanics as to how much computing power you can do with silicon.  

You can watch the video here.

The Science of the Ponytail

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In more bizarre scientific research, physicists have come up with an equation that explains and predicts the shape of a ponytail.

Professor Raymond Goldstein worked on the equation with Professor Robin Ball from the University of Warwick and Patrick Warren, from Unilever’s Research and Development Centre. According to them, this equation aims to “solve a problem that has puzzled scientists and artists ever since Leonardo da Vinci remarked on the fluid-like streamlines of hair in his notebooks 500 years ago”.

The abstract of the paper, which will appear in Physical Review Letters Journal, follows:

A general continuum theory for the distribution of hairs in a bundle is developed, treating individual fibers as elastic filaments with random intrinsic curvatures. Applying this formalism to the iconic problem of the ponytail, the combined effects of bending elasticity, gravity, and orientational disorder are recast as a differential equation for the envelope of the bundle, in which the compressibility enters through an “equation of state.” From this, we identify the balance of forces in various regions of the ponytail, extract a remarkably simple equation of state from laboratory measurements of human ponytails, and relate the pressure to the measured random curvatures of individual hairs.

The best part? The scientists have come up with a new mathematical quantity known as the Rapunzel Number. Very clever.

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(via BBC News)