Why do we have fingerprints? How long can trees live? Why do cats purr? Artists illustrate humanity’s most burning scientific questions.
Why do we have fingerprints? Do immortal creatures exist? How do migrating animals navigate?
In a new book called The Where, The Why, And The How, 75 artists set out to illustrate some of the biggest, strangest, most curious scientific mysteries of our time.
Kelimutu is a volcanic peak in Indonesia that has three crater lakes, each displaying water with a different color! The Lake of Old People (Tiwu Ata Mbupu) is blue, the Lake of Young Men and Maidens (Tiwu Nuwa Muri Koo Fai) is green, and the Enchanted Lake (Tiwu Ata Polo) is a dark murky color that sometimes appears red. The exact color of all three lakes changes somewhat, and the tints are thought to be the result of gasses released from the earth underneath, interacting with the ecosystem in different ways for each crater. Each lake has its own spiritual meaning as well. read about them and see more pictures at Kuriositas.
It doesn’t take a genius to realize dry ice is awesome, and with Halloween right around the corner, you’re bound to be seeing a lot of it. But did you know dry ice bubbles can be used as a practical effect to make whirling, churning alien planets?
Like all good practical effects, the premise is simple; just create a soap film over a chunk of sublimating dry ice to capture the gaseous clouds in a fragile globe. Shoot it the right way, and you could swear you’re staring at some unknown gas giant, floating in the furthest reaches of space. You’d be hard-pressed to find an easier way to make planets in your kitchen.
Rob Kesseler est un photographe et professeur britannique qui s’intéresse aux détails microscopiques de la flore exotique. A le frontière entre art et science, ses représentations utilisent des photographies microscopiques modifiées et colorées pour donner des visuels d’une beauté saisissante. Plus dans la suite.
How many times have you heard people say “I can’t believe my eyes?” well, you’re about to join them.
Above with the beard is a chap called Vsauce
Now you might not have heard of him previously, (but the word is getting out) but he’s science boffin & curator of a popular YouTube channel where he uploads clips to dispel the myths and reasons behind some scientific facts and secrets.
It’s all very interesting (if you have time) but perhaps his most successful video (with 6M+ views) is one where he recently covered the topic of “Colour”, how it’s perceived differently by our brains to how our eye ultimately recalibrate it.
After watching, you’ll be scratching you head – can we really believe anything we see anymore?
Answer? Probably not.
Which each passing year, the world gets thirstier. As the human population continues to grow, and becomes more urbanized, our sources of drinkable water get pushed to their limits. The solution? Desalination — the process of removing salt from ocean water. But given the tremendous costs and energy requirements of doing so, large-scale desalination remains out of reach for the foreseeable future.
But that doesn’t mean it’s not coming. The solution could come from our sun — a prospect that will finally make desalination a viable global option in the coming decades. Here’s how it’s going to work.
Top image: Walt Stoneburner/Flickr.
What’s the problem?
Humanity’s need for water is steadily increasing. Escalating population rates are placing an incredible demand on available water sources — but there’s more to it than that. It’s estimated that upwards of 70% of all potable water goes into agriculture, which in turn is causing bodies of fresh water to be rapidly drained.
And it’s not so much that water is being depleted, as it’s being redistributed. Water that falls from the sky doesn’t get distributed equally around the globe, which is why the demand for water isn’t the same everywhere.
Moreover, we can’t move water. Well, actually we can — but it’s incredibly expensive. China, for example, is working on a $62 billion project to build a pipe-and-canal system to transport water over hundreds of kilometers from the Yangtze River to parched cities and farms in the north. In California, nearly 20% of all electricity is used to move water around. The impact on the environment, including associated carbon emissions, is not trivial.
As for today’s desalination plants, they can only really be used on a small scale, on account of their intense energy requirements. The practice of manually heating saltwater to remove salt with traditional power sources simply doesn’t make economic and environmental sense in an era that’s striving for sustainability. Additionally, some of the more water-poor areas of the world are located in developing countries, where these technologies are largely out of reach. And even if access isn’t a problem, cost certainly is.
Why solar power?
This is why experts believe it’s critical that we develop accessible, affordable, and industrial-scale solutions for desalination — and this is where solar power comes in. And indeed, the advent of concentrated solar power (CSP) may finally offer a viable and sustainable alternative to fossil fuels for what will eventually become large scale seawater desalination.
What’s both interesting and exciting about CSP is that the technology already exists. This issue right now is primarily one of cost. Solar panels, or more specifically photovoltaic cells, still cost as much (if not more) than the equivalent in fossil fuels like natural gas and coal.
But despite the current cost, the future of CSP as a means to power desalination plants looks particularly bright. When considering the potential power of a CSP plant, it quickly becomes obvious as to why this is the case.
It’s suspected, for example, that a CSP plant the size of Lake Nasser in Egypt would be capable of harvesting an amount of energy equal to present Middle East oil production. The total solar energy received on each square kilometre of desert land could desalinate an amount of 165,000 cubic meters per day, or 60 million cubic meters per year.
That’s a lot of water.
How does it work?
Interestingly, desalination is actually an afterthought to the development of a more efficient kind of solar power, what has been dubbed hot solar cells. A recent innovation allows for more efficient solar panels by pumping water through micro-channels on the surface of the panels. Concentrated photovoltaic (CPV) cells use lenses to focus large areas of solar energy onto a small patch of photovoltaic material.
The trouble is, temperatures can reach 120°C, making them quite inefficient — and reducing the amount of electricity they can produce. But it’s the process of cooling them down where it gets interesting. By using the same technology developed to cool computer chips, water-filled microchannels can be used to cool the cell — and the residual hot water is in turn used for desalination. This solves two problems at once: electricity and desalination.
Looking a bit deeper into the process, IBM has developed a microchannel that is etched onto the cell itself. This makes for better cooling because the water is closer to the heat source. Tests have shown that a one centimeter ultra-high CPV cell can still function between 70 to 90°C — even with 5,000 times the normal amount of solar radiation focused on it (which is five times as much as existing CPVs can handle).
This makes the CPV method far more economic and efficient when compared to the traditional method of desalination which uses hot water to distill seawater.
There is another idea called the Flat Mirror Solar Collector. By using flat mirrors instead of parabolic ones, panels can be made to follow the movement of the sun from east to west, allowing for the concentration of the sunrays from a large area to a fixed horizontal tube on top containing water under pressure. As a result, the concentrated sunrays raise the temperature to produce steam in the tube, which is then used to drive a conventional steam turbine. The waste heat at the end of the turbine can then be used to desalinate seawater.
Who’s doing it?
While these technologies are still prohibitively expensive, this hasn’t stopped some countries from getting an early start.
Cyprus recently completed a 16-month pilot project to test the feasibility of the concept. They combined a thermodynamical cycle for the production of water while simultaneously producing economically competitive green energy. The next phase will see the installation of a full-scale plant, with the third phase seeing the deployment of refined technology plants for heavy-load commercial operation. The Cypriot government is currently hoping to secure 18 million euros (USD$22.5 million) to keep the project going.
Egyptians are currently working on a four-year test project called Multi-Purpose Applications by Thermodynamic Solar, or MATS. It has received 22 million euros (USD$28 million) from the European Union under a special program. They’re planning to build a test site in Burj Al Arab, a desert area near Alexandria. Their units will be powered by both solar energy and renewable energy sources such as biomass and biogass. It’s expected that the test facility will generate one megawatt of electrical power and 250 cubic metres of desalinated water per day.
Australia’s Acquasol Infrastructure, a company that designs and develops affordable, environmentally-friendly power and water projects, is working on a project called “Acquasol 1” — a concentrating solar power plant that will also double as a desalination station. It will be built just outside Port Augusta, South Australia, and serve as a 200 Mw Solar thermal/gas hybrid facility. They’re also planning on using the excess brine derived from desalination to create commercial grade salt.
Other countries are also looking to get in on the action, including Saudia Arabia.
When will everyone have access?
This is ultimately the big question.
Experts predict that the growing freshwater deficits could be increasingly covered starting in the 2020s, and possibly as late as the 2030s. The spread of CSP desalination plants will likely reduce non-sustainable water supply and inspire the development of most of potable water production by the year 2030 and afterwards.
All this is contingent, of course, on the price of photovoltaic cells dropping — which they probably will in time. Current state of the art CSP costs the equivalent of about $50/barrel of fuel oil, but it’s thought that there will be a 50% cost decrease in the current decade due to economies of scale, mass production, and technological progress. As a result, we could achieve a cost level of $25/barrel within 10 years, and $15 per barrel by the middle of the century — a rate of decline that simply cannot be matched by fossil fuels.
The result: Large scale CSP desalination plants in parts of the world who need it the most by the 2030s.
Nerve cells—dyed red in the above image—are responsible for squids’ shimmering displays of iridescence, new research shows.
A squid’s shifting metallic sheen comes from clusters of tiny platelike structures inside their skin cells. (See squid pictures.)
Known as iridophores, the microscopic ensemble interferes with the way certain wavelengths of light are reflected.
“It’s the same effect you get with shiny colors on a soap bubble or a thin layer of oil on the water surface in a harbor,” said study co-author Paloma Gonzalez-Bellido, a neuroethologist at the Marine Biological Laboratory in Woods Hole, Massachusetts.
Exactly how squid turn these iridophores on and off has, until now, remained a mystery.
A new technique allowed the team to hook up electrodes to individual nerves in squid skin. When they sent electrical impulses into the nerves, the iridophores changed color and brightness.
Longfin inshore squid (pictured) use nerves to control iridescence in their skin—and it’s likely that other squid species do the same thing, said study co-authorTrevor Wardill, also of the Marine Biological Laboratory.
However, it may take time to discover whether close relatives of squid—including cuttlefish and octopus—shimmer via the same process because of the complex neurons and muscles in their skin.
“We can stimulate the skin of cuttlefish, but they are very difficult to work with,” said Wardill, whose study appeared recently in the journal Proceedings of the Royal Society B. “Squid are a simple version.”
A close-up photograph of squid skin shows two varieties of colored spots—darkly pigmented chromatophores overlaying brightly shining iridophores.
Squid can control the color of their skin despite being color-blind. They see predominantly blue light using a single visual pigment in their eyes.
“In the ocean environment once you go down to 60 feet (20 meters), most colors are all washed out,” Wardill said. “So for squid, maybe color is not really important.”
A patch of iridescent squid skin, known as an iridophore, shines brightly after being stimulated by electric pulses.
The role that color-shifting iridescence plays in the lives of squid is still not fully understood.
“As far as we can tell the iridescence is used on a daily basis, potentially for aggression, and it may be involved in camouflage as well,” said Wardill.
“Certainly when the animals are very aggravated, you can see their iridescence gets quite bright, but what they’re actually telling their fellow squid is hard to know.”
Squid adjust their metalic gleam using iridophores in their skin (indicated with an arrow) that are formed from clusters of individual cells called iridocytes, as seen here under a microscope.
The large white objects in this image with pink centers are chromatophores, the pigmented bodies that give squid their darker, changeable colors.
“We not only saw the chromatophores expand, but also saw the iridophores change reflectance, so they change brightness and color,” explained study co-author Wardill.
“The amount of change varies a little bit from one iridophore to the next,” he added.
Scientists use a glass electrode to send pulses along a squid nerve cell, causing the skin to change color.
“The color change takes around 15 seconds, during which time it shifts through the rainbow of colors,” Wardill said.
“It starts at reds and goes through the yellows and then greens, and through to the blues,” he said.
To avoid damaging delicate tissues, the squid skin was dissected from the underside. The two black patches visible in the image are small holes cut through the skin to access nerve bundles.
Squid nerve cells responsible for switching on iridescence glow red in a microscope image.
Iridescence is seen in other animals, but is often fixed, as in butterflies.
“There are fish that have variable iridescence as well, they can have stripes or different patterns on their body surface,” Wardill said.
“But cephalopods [squid, cuttlefish, and octopus] are much better at it than fish,” he added.
Highlighted in green, a nerve divides into intricate filaments deep within a patch of iridescent squid skin.
The research team is now searching for synapses at the end of these nerve fibers, which release neurotransmitter chemicals that turn on the glittering display.
“We can see down to half a micron, but haven’t found the terminals,” Wardill said.
Instead, he thinks the squid could potentially release chemicals at specific sites along the length of the nerves.
“We’re now working on trying to figure out where are the specific sites that neurotransmitter is released,” he added.
Inside the Iridescence
The fine structure inside iridescent squid-skin cells is seen in blue at very high magnification.
In continuing research, the team has discovered that there are nerve cells dedicated exclusively to switching on the reflecting structures that give squid their changing shine.
“It seems that the brain does have the ability to individually control iridophores,” said study co-author Gonzalez-Bellido.
Added Wardill, the “next big question is how neurons individually control the color and brightness.”
This isn’t just from The Avengers movie, it is in the comics also. Here an image of the S.H.I.E.L.D.’s helicarrier.
Could something like this really fly? Let me see if I can use my approximation from the human powered helicopter to estimate the amount of power needed to fly this thing. First, some assumptions.
- I will use the helicarrier shown above from the recent The Avengers movie. There are other variations of this thing in the comics.
- The expressions for force and power from my previous post are mostly valid. I know that some people freak out over that estimation – but it isn’t terrible as far as estimations go.
- There are no special aerodynamic effects to help the helicarrier hover – like ground effects.
- The helicarrier in the movie is about the size and mass of a real aircraft carrier.
- The helicarrier stays in the air just from the rotors. It doesn’t float like a lighter than air aircraft. I think this assumption does along with the movie since they show it sitting in water floating like a normal aircraft carrier.
Just as a reminder, for a hovering craft I estimated it the force from pushing the air down (and thus the lift) would be:
As a reminder, the A is the area of the air that is pushed down – which would be the size of the rotors and v is the speed that the rotors push the air.
Helicarrier Mass and Length
This helicarrier clearly isn’t a Nimitz Class Carrier – but something else. However, it seems to be a good guess that they are the same size. Here is a comparison with a Nimitz class carrier.
The runways look about the same width, so I am going to say the length and the mass of the helicarrier is about the same. Wikipedia lists the length at 333 meters with a mass of about 108 kg.
Using the length of the helicarrier, I can get an estimate for the size of the rotors. With each rotor having a radius of about 17.8 meters, this would put the total rotor area at 4000 m2 (assuming all the rotors are the same size).
Thrust Speed and Power
When the helicarrier is hovering, the thrust force would have the same magnitude as the weight. From this, I can get an estimate of the speed the rotors would move the air down.
Just to make things easier, I will look at low level hovering. This means I can just use 1.2 kg/m3 for the density of air. Of course, at higher altitudes the density would be lower. Using the mass and rotor area from above, I get a thrust air speed of 642 m/s (1400 mph). Just to be clear, this is faster than the speed of sound. It is probably clear that I don’t know much about real helicopters or jet engines, but I would suspect that a thrust this high would add other calculation complications. I will (as usual) proceed anyway.
With the air speed, I can now calculate the power needed to hover. Again, I am not going to go over the (possibly bogus) derivation of this power for hovering, it was in my huma-copter post.
With my values from above, I get a power of 3.17 x 1011 Watts – quite a bit more than 1.21 giga watts. In horsepower, this would be 4.26 x 108 horsepower. That’s a lot of horses. Just for comparison, the Nimitz class carriers have a listed propulsion of 1.94 x 108 Watts. I assume this is the maximum power, so it wouldn’t be enough to lift the helicarrier. Obviously, the S.H.I.E.L.D. helicarrier has a better power source. I would guess it would have to be at least around 2 x 109 Watts in order to operate. You don’t want to use your maximum power just to sit still.
Really, I am surprised with my rough calculations that it is even partially close to the power output of a real carrier.
Why didn’t I think to look at some real helicopters before? There are two things I can look up for different helicopters: the rotor size and the mass. Of course, I don’t know the thrust air speed, but I can find that. Let me get the power needed to hover as a function of mass and rotor size. Starting with the force needed to hover, I know an expression for the thrust air speed. If I substitute this into the expression for the power, I get:
Now for some data. Here are some values I found on Wikipedia.
What if I look at the actual power for these aircraft compared to my “minimum power to hover”? Since my (possibly bogus) calculation just depends on the mass and the area of the rotors, there is nothing to stop me.
Honestly, I didn’t expect this to turn out so nice and linear. The slope for this linear regression line is 0.41 and the intercept is 14.4 kW. So, what does this mean? For the slope, this means that my calculated power (based on the rotor area) is 41% of the actual maximum power available for these aircraft. Now, this doesn’t exactly mean that a hovering helicopter would be running the engines at 41%. It could mean that there is also some other factor that should be in my calculation.
What about the 14.4 kW intercept? First, this is essentially zero in comparison to these engine powers. The smallest engine is 310 kilo watts. Second, I was going to say something about engine power just need to run the other stuff (overhead power) but the way I plotted that it would have to have a negative intercept. Let me just stick with “this is almost zero”.
How about some other plots? Here is something interesting. This is a plot of thrust air speed vs. mass of the helicopter.
The cool part is that there doesn’t seem to be a real pattern. The bigger helicopters push the air down (in my model) such that the air leaves with a speed around 28 m/s. This is much slower than than the calculated air speed for the helicarrier at 642 m/s. You know what comes next, right? Now I will calculate the size the rotors on the helicarrier would need to be to let it hover with a thrust air speed of 28 m/s. Let me go ahead and increase this to 50 m/s thrust speed – because it’s S.H.I.E.L.D..
I don’t need to power to find the area, I will just use the expression I used to find the velocity of the air and solve for the area of the rotors instead.
Now I just need to plug in my values for the mass of the helicarrier, the thrust air speed and the density of air (I am using the value at sea level). This gives a rotor area of 6.5 x 105 m2. This is quite a bit larger than my measured values from the image. I guess I will have to fix the image.
Yes, that looks crazy. But remember, I even used a higher than expected thrust speed. If I used 30 m/s, it would be even crazier big. Crazy.
Remember the rule with all assigned homework problems: if you wait too long to figure this out, I might do it instead.
1. This question is about the size of the helicarrier. Suppose the size is NOT the same as a Nimitz class carrier. Suppose it is smaller such that the rotor area is the correct size for a thrust air speed of 50 m/s. How big is the helicarrier in this case? (hint: assume a carrier density of about 500 kg/m3 since about half of it floats above the water line).
2. (SPOILER ALERT) When Iron Man tries to restart one of the rotors, he pushes it to get it going. Suppose the rotor pushes the air to a speed of 642 m/s – and this is the linear speed of the middle of the rotor. How fast was Iron Man flying around in a circle to get the thing started? You might want to assume the rotors at this point were only at half speed. What would be the g-force Iron Man would experience moving this fast in a circle? Would that kill him?
3. What about at operating speed for the rotors – would would the acceleration of the tip of the rotor blade be? Estimate the tension in the rotor blades (where would the tension be a maximum)? Is this too high of a tension for known materials?
Images courtesy Walt Disney Pictures
Minute Physics creator Henry Reich doesn’t shrink from tackling the big bangand other big deals in science, so it makes sense that he’s now making sense of the Higgs boson. His timing is excellent, considering that the subatomic particle appears to have been discovered at Europe’s $10 billion Large Hadron Collider. In today’s three-minute video, Minute Physics explains how the Higgs boson subatomic particle fits into the bigger puzzle of the universe’s structure at the lowest level … and why physicists hope this isn’t the end of the story.
But be forewarned: This is the first part of what’s expected to be a three-part video series. And although Reich is well-versed in film as well as physics, this isn’t a one-man operation. Reich relies on experts at Canada’s Perimeter Institute for support and scientific back-stopping. So stay tuned for future installments of Minute Physics’ Higgs boson saga.
The Godless Particle
Notice that the video makes no mention of the Higgs boson as the “God particle.” That’s a label that Nobel-winning physicist gave to the god-danged particle decades ago, but since then, scientists have come to loathe the term. In fact, the boson is better described as the “Godless Particle,” says Lawrence Krauss, a theoretical physicist at Arizona State University. Here’s his perspective, distilled into an email:
“The Higgs boson actually should probably be called the Godless particle. The background ‘Higgs’ field permeates all of space and is largely responsible for the existence of stars, planets and humans. The confirmation of the existence of this field strongly supports what modern physics has said for years: The many features of our universe can be largely accidental consequences of the conditions associated with the universe’s ‘birth,’ consistent with the laws of physics.
“Far from suggesting any higher power, the discovery at CERN takes particle physics one step further toward answering the question: ‘Why is there something rather than nothing?’ … by demonstrating the plausibility of the idea that everything we see could arise naturally from an initial state of no particles, and maybe no space, and maybe even no fixed laws — without supernatural shenanigans.”
You’ll be hearing a lot more about the Godless Particle from Krauss in the days ahead: He’s writing an article on that theme for Newsweek, as well as an essay explaining the significance and physics of the discovery for The New York Times’ Science Times section. To get the full cosmic story, you’ll want to check out Krauss’ latest book, “A Universe From Nothing.”
The possible discovery of the Higgs boson at CERN is obviously of tremendous importance to our understanding of the universe, but how does one explain the Higgs boson to a layperson, a child, an idiot? A lot depends on who you’re talking to, and what they want to hear. Just use this handy guide to selective explanation:
For people you’re trying to impress: “The Higgs boson is an elementary scalar particle first posited in 1962, as a potential byproduct of the mechanism by which a hypothetical, ubiquitous quantum field – the so-called Higgs field – gives mass to elementary particles. More specifically, in the standard model of particle physics, the existence of the Higgs boson explains how spontaneous breaking of electroweak symmetry takes place in nature.”
For harassed, sleep-deprived parents: “If the constituent parts of matter were sticky-faced toddlers, then the Higgs field would be like one of those ball pits they have in the children’s play area at IKEA. Each coloured plastic ball represents a Higgs boson: collectively they provide the essential drag that stops your toddler/electron falling to the bottom of the universe, where all the snakes and hypodermic needles are.”
For English undergraduates: “The Higgs boson (pronounced “boatswain”) is a type of subatomic punctuation with a weight somewhere between a tiny semicolon and an invisible comma. Without it the universe would be a meaningless cloud of gibberish – a bit like The Da Vinci Code, if you read that.”
For teenagers studying A-level physics: “No, I know it’s not an atom. I didn’t say it was. Well, I meant a particle. Yes, I do know what electromagnetism is, thank you very much – unified forces, Einstein, blah blah blah, mass unaccounted for, yadda yadda, quarks, Higgs boson, the end. It was a long time ago, and I’m tired. Change the channel – we’re missing Come Dine With Me.”
For a member of the Taxpayers’ Alliance: “Its discovery is a colossal, unprecedented, almost infinite waste of money.”
For a child in the back seat of a car: “It’s a particle that some scientists have been looking for. Because they knew that without it the universe would be impossible. Because without it, the other particles in the universe wouldn’t have mass. Because they would all continue to travel at the speed of light, just like photons do. Because I just said they would, and if you ask ‘Why?’ one more time we’re not stopping at Burger King.”
For religious fundamentalists: “There is no Higgs boson.”