“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?”—Alan Watts, The State of Nothing
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!
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.
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.
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!
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.
Your discussion of the double-slit experiment appeared first on my dash today! Having discussed Young, could you now talk to your readers about Einstein and his Nobel-winning work with the photoelectric effect? (pretty please?)
So, we already know from Young’s double slit experiment that light can act like a wave, but when interacting with matter, light acts as a particle. In 1905, Einstein postulated that light is transmitted in bundles of energy called photons. These bundles, otherwise known as quanta, are made up of discrete amounts of energy as given by E=hf (Energy = frequency * Planck’s constant).
Einstein theorised their existence to explain the photoelectric effect: the emission of electrons by metals when irradiated by short wavelength, high frequency light. In other words, when light shines on metal, photons are absorbed and electrons are released. Einstein thought that if a photon has a frequency over a certain threshold, it would have sufficient energy to transfer to an electron and eject it from the metal.
Think of it this way: a piece of metal is made up of a sea of atoms, which are in turn made up of smaller particles including electrons. These are like tethered boys, bound to their atom. But this tether can be broken if a wave comes along strong enough to set the electrons adrift from the metal.
In the right conditions, photons can collide with the electrons and instantaneously transfer all of their energy to them. (It’s important to remember that photons can never just transfer part of their energy, it has to be all.) This gives the electrons enough energy to escape their bonds. The amount of energy needed varies from metal to metal—each one has a threshold frequency, which sets the minimum frequency of photon needed to free one its electrons (remember, its frequency is directly proportional to its energy). If a photon has an energy any lower than the frequency, it can’t transfer its energy and the electrons will not be emitted.
The electrons are emitted with a range of energies, because after spending the energy necessary to escape, some have energy left over. This depends on the frequency of the photon. (EK(max)=hf—W, where W=h * threshold frequency.)
If we think of it in terms of our ocean metaphor, we might assume that the more intense the light (i.e. the more number of photons hit the metal), the more energetic the emitted electrons would be—after all, monstrous swells would send buoys sweeping across the ocean. But the intensity has no effect on the electrons’ kinetic energy. In fact, electrons ejected using a bright source have the same energy as those ejected using a very dim source—if both sources of light had the same frequency. Kinetic energy increases as frequency increases, though it is also true that the more intense the light, the more electrons emitted, keeping with the law of conservation of energy.
Fun fact: the photoelectric effect releases visible light for alkali metals, near-ultraviolet light for other metals, and extreme-ultraviolet radiation for non-metals.
Hey! I really liked your post on the double slit experiment, but you didn't mention my favorite part: it also works with electrons, something we normally think of as particles! Even cooler, if you only shoot one electron at a time through the slits, you also get a diffraction pattern! But, if you have a detector to see which of the two slits the electron moves through, you only get the two lines you would get from a particle, showing that electrons behave differently if you're looking at them!
This is very true, and very cool! French physicist Louis de Broglie first suggested that not only do photons have wave-particle duality, but ALL particles do.
The Davisson-Germer experiment confirmed de Broglie’s claim: electrons were fired at a nickel crystal, and after hitting it, they scattered to form an electron diffraction pattern—the evenly-spaced atoms of the crystal acted like a diffraction grating. This pattern was compared to the diffraction patterns of x-rays on crystal, and electrons were thus shown to exhibit a wave behaviour.
de Broglie also devised a way to assign wavelengths to particles like electrons, protons and neutrons, using their momentum (λ=h/p).
“It is important for scientists to be aware of what our discoveries mean, socially and politically. It’s a noble goal that science should be apolitical, acultural, and asocial, but it can’t be, because it’s done by people who are all those things.”— Mae Jemison, the first black woman in space. (via coolchicksfromhistory)
are you a star because i'm getting pulled in by your gravity also it's really hot here like really really hot maybe you should stand a little farther away from me because you're literally killing me i can feel my flesh cooking i am in so much pain
Jellies! I went to an aquarium today and I am completely fascinated by them! So, what's the deal with jellies? What do their gelatinous bodies consist of, structure wise? Also, are they made up of jelly or jam? Strawberry...or grape?
No but really, weirdly enough, jellyfish are actually made up primarily of water—depending on the species, between 95% and 98% of a jellyfish’s body mass is water.
What we’d call the “jelly” of a jellyfish is actually a thick, elastic substance called mesoglea, which is sandwiched on either side by two layers: the outer epidermis, and the inner gastrodermis. The mesoglea is mostly water but also composed of fibrous proteins, and it essentially serves as a skeleton-substitute, keeping the jellyfish’s body together. It needs water to support its weight, though, which is why when you take a jellyfish out of water, suddenly it’s no longer a mysterious and elegant creature; it’s just a blob. If a jellyfish washes up on a beach, it will collapse and pretty much almost disappear as all the water inside of it evaporates.
So that’s the deal with their jelly, but jellyfish are actually incredibly cool so here are a few more tidbits:
They belong to the phylum Cnidaria, and like all members of that phylum, they’re radially symmetrical. This means that their body parts radiate out from a central axis, which runs the length of their body from the top to the end of their tentacles. If you cut a jellyfish in half at any place along that axis, you’d get two symmetrical halves. This is pretty useful, because it allows them to respond to food or danger from all directions.
Even weirder is how they even know there’s food or danger to respond to. Jellyfish have no brains, no blood, no heart, and no central nervous system—but they do have a very elementary network of nerves located in the epidermis. Called the “nerve net”, it can detect a variety of stimuli including the touch of other animals, to help with catching prey. Some jellyfish also have ocelli, which are rudimentary eyes—they’re light-sensitive organs that don’t form images, but they detect light and can help the jellyfish tell up from down, so they can orient themselves.
The box jellyfish in particular has 24 eyes, two of which can see colour, and it’s one of the very few creatures that has a 360 degree view of its environment. I was TERRIFIED of them as a child, and it looks like that was for good reason. (Also, box jellyfish are one of the most venomous creatures on the planet, so that might have had something to do with it.)
Their blobby bodies, weird eyes and terrifying tentacles must work pretty well for them, because jellyfish have roamed the oceans for at least 500 million years, possibly even longer—and they’re actually the oldest multi-organ animal!
In the bedroom with Giant Sea Bass: Investigating mating behavior of an endangered megacarnivore
If anyone has an extra few dollars and is looking for something science-y to support, you might want to listen up. A Masters student at California State University, Northridge, is trying to fund his thesis by using crowdfunding on the site Experiment.com, which is a relatively new and very cool endeavour to bring science funding back to grassroots! If you want to donate to help conserve the endangered Giant Sea Bass, head on over and check out the project.
Essentially, the double slit experiment shows that light exhibits dual wave/particle behaviour. It was first offered up by Thomas Young in the late nineteenth century, which is why it’s called the Young’s Double Slit Experiment.
Here’s how it goes down: A monochromatic (single colour/wavelength) light is shone towards a blank screen, and placed between them is a screen with two parallel slits cut into it. If light is just a particle, then it would simply shine through the slits and hit the blank screen in two lines, kind of how spray paint can follows the shape of a stencil. But it doesn’t. It shines on the screen as parallel bands, or fringes.
This is because in this instance, light is acting like a wave, so when it passes through the slits, it diffracts—i.e., it spreads out after passing through a narrow opening. This happens from both openings, so instead of two straight beams of particles, the light becomes two diffracting waves, like this:
As they both hit the screen, at some points the waves will meet crest-to-crest, which increases the intensity of the wave (constructive interference), and at other points they’ll meet crest-to-trough, which decreases the intensity of the wave because they cancel each other out (destructive interference). On the screen, the bright lines correspond to the maximum intensities, and the dark lines correspond to the minimum intensities. The combination of these is called an interference pattern.
This experiment is important because it shows that photons can also act as waves, since particles don’t diffract, thus demonstrating the principle of wave-particle duality!
I apologize if this has been asked, but why does the placebo effect work?
For those who don’t know, the placebo effect is when an inert medical treatment—like a sugar pill—actually has a positive effect on a patient’s condition. People essentially trick themselves into becoming better simply because they believe they will.
It’s not just about taking dummy pills; patients who are treated by a warm, caring practitioner seem to recover sooner from mild conditions strep throat and the common cold—which suggests they have a certain expectation that this person will make them better.
We’re not fully agreed on how, why, and when it works. It’s actually one of the strangest and least-understood phenomena in medicine. But studies have shown that when treated with placebos, our brains release pain-relieving opioids, which at least help along the healing process.
There are a few theories about why this happens:
It’s all in the patient’s head, and their expectation that a treatment will help actually activates a physiological response
It’s all in the patient’s body, which remembers how it felt after taking medication previously, so it automatically releases neurotransmitters that begin the healing process (sort of like conditioning: our body may be conditioned to react positively in medical situations)
Or a mixture of both: expectation and conditioning
The effect is highly variable, and seems to work better for “subjective” cases (like simply reducing the feeling of pain) rather than “objective” cases (like reducing blood pressure).
Some fun facts about the placebo effect:
It can still work even when you know it’s a placebo. Harvard researcher Dr. Ted Kaptchuk studied migraine-sufferers, and found that even the patients who knew they were taken a dummy pill still experienced pain relief
The opposite of the placebo effect is the nocebo effect—when the patient is expecting a negative outcome, then their injury or illness may be negatively affected. A study in Italy gave what they claimed was lactose to patients, some of whom were lactose-intolerant. Even though the lactose wasn’t really lactose, 44% of those with the intolerance and 26% without it showed symptoms of gastrointestinal discomfort.
The shape, size, colour and branding of the pills subconsciously affect how well they work—yellow pills are “best” at treating depression, green are best at easing anxiety, and pills with brand names on them are more effective than blank ones.
The effect seems to have become more “powerful” over the years. It was first documented in the late 1700s, but has become stronger and stronger up until the present day. This is likely due to social conditioning; humans are becoming more trusting of medicine.
So, to sum up: the placebo effect is weird, so I can’t give you a straight answer!
I did an REU last year, and I am applying to 10 more this year. The apps are due Feb 1-March 1st & you have to be a US citizen for most of the NSF REUs. If anyone has any questions about the process or REUs in general, I can help :)
Oh, that’s so cool. Here’s an experienced source of information for you all!
How does one find internships? Unfortunately, many of my peers are having trouble finding science-related internships, mainly ones relating to lab work, and I myself don't know where to start.
Google is your friend. Get intimate with it. There are a lot of databases/lists of internships floating around, but you usually have to dig a bit to find them.
Here’s an incomplete list of ones I’ve personally taken note of. Most are in the US or the UK, and they’re mostly available to international students. There are MANY more programs open to US and EU citizens; you guys have a lot more options.
LISTS of STEM internships/programs in all fields:
Berkeley (geared towards Medical/Health Sciences but with lots of general links too)