18th Apr 2014
"If you think of this idea of nothingness as mere blankness, and you hold onto this idea of blankness, you haven’t understood it. Nothingness is really like the nothingness of space, which contains the whole universe. All the sun, moon and stars, and the mountains and rivers, and the good men and bad men, and the animals and the insects, the whole bit—all are contained in the void. So out of this void comes everything and you are it. What else could you be?"
Source: Alan Watts, The State of Nothing
1st Apr 2014
Van der Waals helps geckoes scale walls
Face it, it would be totally cool if we could clamber up surfaces as easily as geckoes do. We could scale skyscrapers, never fear when climbing ladders, and could completely eliminate that tacky dramatic moment in movies where the hero dangles precariously over the street a hundred storeys below. Of course, their sweaty fingers would never slip if they had some kind of adhesion mechanism—they could just climb right back up.
So how do geckoes manage it?
Well, unlike humans, geckoes have millions of microscopic hairs on the bottom of their feet, called setae. The tips of each of these setae are split into 100-1000 spatulae, which are so small that they’re narrower than the wavelength of visible light—less than 300 nano metres.
Clearly, some kind of intermolecular force between the gecko’s feet and a surface is responsible for adhesion, but it wasn’t until research in 2002 that we fully understood what was going in—for a while, scientists were throwing around theories like suction and chemical bonding. 
Turns out, geckoes take advantage of the Van der Waals force.
Named after a nineteenth century Dutch physicist, Van der Waals forces are weak electrodynamic forces that act over tiny distances, yet bond almost any material. They’re created by fluctuations in charge distributions between molecules.
These weak forces can be strengthened as more and more of one surface touches the other—like, say if you had billions of spatulae coating your feet. These tiny hairs increase surface density, so on contact with the wall the gecko experiences a strong adhesive force
Essentially, this force means we can improve adhesion simply by increasing surface density, like subdividing a surface into countless small protrusions. It means that geometry—not chemistry—is the driving mechanism. A single setae can lift an ant; a million could lift a 20 kg child; and if geckoes used every setae simultaneously, they could support 130 kg.
These forces open up to a lot of applications in adhesives. Engineers at Berkeley and Stanford have developed biologically inspired synthetic adhesives that adhere like gecko pads, which have even been used on robotic climbers.

Van der Waals helps geckoes scale walls

Face it, it would be totally cool if we could clamber up surfaces as easily as geckoes do. We could scale skyscrapers, never fear when climbing ladders, and could completely eliminate that tacky dramatic moment in movies where the hero dangles precariously over the street a hundred storeys below. Of course, their sweaty fingers would never slip if they had some kind of adhesion mechanism—they could just climb right back up.

So how do geckoes manage it?

Well, unlike humans, geckoes have millions of microscopic hairs on the bottom of their feet, called setae. The tips of each of these setae are split into 100-1000 spatulae, which are so small that they’re narrower than the wavelength of visible light—less than 300 nano metres.

Clearly, some kind of intermolecular force between the gecko’s feet and a surface is responsible for adhesion, but it wasn’t until research in 2002 that we fully understood what was going in—for a while, scientists were throwing around theories like suction and chemical bonding.

Turns out, geckoes take advantage of the Van der Waals force.

Named after a nineteenth century Dutch physicist, Van der Waals forces are weak electrodynamic forces that act over tiny distances, yet bond almost any material. They’re created by fluctuations in charge distributions between molecules.

These weak forces can be strengthened as more and more of one surface touches the other—like, say if you had billions of spatulae coating your feet. These tiny hairs increase surface density, so on contact with the wall the gecko experiences a strong adhesive force

Essentially, this force means we can improve adhesion simply by increasing surface density, like subdividing a surface into countless small protrusions. It means that geometry—not chemistry—is the driving mechanism. A single setae can lift an ant; a million could lift a 20 kg child; and if geckoes used every setae simultaneously, they could support 130 kg.

These forces open up to a lot of applications in adhesives. Engineers at Berkeley and Stanford have developed biologically inspired synthetic adhesives that adhere like gecko pads, which have even been used on robotic climbers.

15th Mar 2014

So I started uni a couple of weeks ago, and along with work+personal projects+writing for the student magazine+social life, it’s been sucking up a whole lot of my time. When I am actually home, usually I’m so exhausted or so laden with homework that I don’t have time to write for you guys.

BUT, I’ve been learning a lot of cool things that I want to write about, so I’m going to try and manage my time better and post at least a couple of articles per week!

15th Mar 2014

me-myself-and-iron replied to your post “HOW EXCITED ARE YOU FOR COSMOS”

Are you not able to access the full episode they posted online?

Nope, but not for lack of trying! If you live in the US you have no idea how many videos on the web are only available in your country.

15th Mar 2014

Anonymous asked: HOW EXCITED ARE YOU FOR COSMOS

I’ll be a 100x more excited when I can legally watch it in my country.

25th Feb 2014

Anonymous asked: Hey in concurrence with the C14 question, could you then explain what type of dating is used for things older than 60000 yrs old (fossils for example)?

Carbon-14 isn’t the only radioactive element found naturally in living beings—there are a whole host of other useful radioisotopes with longer half-lives so we can date much older biological and geological samples with accuracy. For example, Potassium-40 is found naturally in living bodies and has a half-life of 1.26 billion years; Uranium-235 has a half-life of 704 million years; Uranium-238 has a half-life of 4.5 billion years; Thorium-232 has a half-life of 14 billion years; Rubidium-87 has a half-life of 49 billion years, etc…

One of the most well-known is Potassium-40, which forms argon gas as it decays. Argon doesn’t normally combine with other elements, so when minerals form they are originally argon free. But if the mineral contains Potassium-40, then the decay will create fresh argon gas that will be trapped inside. If a geologist simply measures the argon gas inside the mineral, they can calculate how much the Potassium-40 has decayed and therefore when the mineral was formed.

24th Feb 2014

j-mcshane asked: So I understand the concept of carbon dating, but since all matter is as old as the universe, how does it really give an "age?" Love your blog and look forward to your posts btw! :D

Okay, cool question! I’ll give a quick rundown of the concept of carbon dating first, for those who are a bit hazy on the matter.

Carbon dating is a way of determining how old certain biological artifacts are by measuring the amount of Carbon-14 in them. Carbon is a basic building block of life so it’s in all living things, but the normal molar mass is 12. Carbon-14 is an isotope (atoms with the same proton count but different number of neutrons) and is rarer, and it’s manufactured in the upper atmosphere by the collision of cosmic rays in the upper atmosphere, turning ordinary nitrogen atoms into Carbon-14. These atoms combine with oxygen to form carbon dioxide, which is absorbed naturally by plants, and eventually makes its way into all living organisms.

But Carbon-14 isn’t a stable element—like many isotopes, it’s radioactive. It decays, with a half-life of approximately 5,730 years, meaning that every 5,730 years, the amount of Carbon-14 has reduced by half. While the organism is alive, its Carbon-14 atoms are decaying but it’s also taking in new carbon all the time, so the percentage of Carbon-14 in its body is always constant. All living organisms have the same percentage—but as soon as they die, they stop taking in new carbon.

Essentially, in carbon dating we measure the amount of Carbon-14 in a body and use its half-life to calculate how long it’s been since the organism died. For example, if the percentage of carbon-14 is half of what it should be in living organism, then the organism has been dead for 5,730 years. We can measure all kinds of objects that once had living material in them—not just fossils or bones that were once living organisms, but also wood, cloth, plant fibres…anything with organic origin.

This measurement is only accurate for organisms that lived up to around 60,000 years ago, because then the amount of carbon gets so small it’s insignificant.

So, to answer your question more clearly: carbon dating measures the levels of Carbon-14 to determine how long since the living organism died and stopped taking in new Carbon-14.

23rd Feb 2014

A Deadly Night Light

It’s not hard to spot a scorpion—if you’re in the desert in the middle of the night, just switch on a UV lights. Scorpions will light up like Christmas trees, glowing a vibrant blue-green. The ultraviolet light make pigments in their exoskeletons emit visible photons, a property which is called fluorescence. 430-million-year-old fossils suggest that the scorpion family has had this trait for a long time, but no one knows what it’s for.

Some scientists have suggested it’s used as a mating signal, or to lure their prey, or warn off predators, or that it’s an evolutionary leftover from when scorpions weren’t nocturnal and needed natural “sunscreen.” But another explanation is a bit more intriguing: biologist Douglas Gaffin of the University of Oklahoma suggests that scorpions turn UV light from the stars and moon into blue-green light because that’s the colour their eyes are optimised to detect. Essentially, their whole body from tail to pincers is a light collector, which relays sensory information throughout the nervous system.

This make a lot of sense. Glowing brightly, scorpions are a target for predators like rodents and owls, so they need to find shelter, and Gaffin thinks they could do this by using their whole-body as a giant eye—they would easily notice when a shadow fell across their skin, because it would reduce their glow.

“It might be a sort of alarm that’s always going off until the scorpion finds shelter,” he says. “Shade might turn down the alarm on that part of their body, so they preferentially move in that direction.”

In 2010, Carl Kloock tested this: he overexposed one group of scorpions to UV light so that the chemicals in their skin were exhausted, and while a control group that could still glow found shelter easily, the first group spent more time out in the open. Gaffin is trying to retest this in other ways, as overexposing scorpions is actually thought to harm them and thus could affect their behaviour. He has experimented with covering their eyes with foil, which didn’t seem to have any affect, and is now moving on to other materials.

(Image Credit: Matt Reinbold / Wired)

23rd Feb 2014

So I am now in possession of a frankly adorable ipad mini, courtesy of my uni, and I intend to use the gift in good faith. Tell me, science enthusiasts and purveyors of good taste: what are the best science and educational apps?

I’ll compile them into a list for everyone to see once I’ve checked them out!

hit me nerds

?

21st Feb 2014

Anonymous asked: So I've always wondered this when I watch an airplane pass in the day: why do they leave a trail of water vapour in their wake? Does it have to be very humid air? Or cold air?

Those trails are actually called contrails, which is short for “condensation trails.” They’re formed when the hot humid air thrust out of jet exhaust collides with the wet, cold air of the upper atmosphere, condensing into little water droplets that quickly freeze into ice crystals.

Essentially, contrails are a type of cirrus cloud!

The air definitely has to be damp and cold—that’s why sometimes planes don’t leave contrails, or leave contrails that break off and restart again, because in dry air they don’t form, and the sky is a layered mix of air of different moisture levels.