My subjective take on issues in and around science. Profiles of interesting scientists, etc. Also, juicy videos of nature, physics, and chemistry, etc.
“‘Jailer, I’ll tell you an interesting fact. Everything we study, we modify by our study of it. Hence truth eternally eludes us.’
“He did not look convinced, just held out his hands for the plates.
“‘Take crabs, for example, I said ‘We poke them with a stick to see how they behave, and they behave as if poked by a stick.’
He folded his arms, the plates dangling from his fingertips.
“This is, of course, a very simple example,’ I said. Take a subtler example, such as atoms of light. Light, as you know, is one of the four great elements-in common parlance, fire. We study it by bouncing it off polished stones, or bending it in water, or squeezing it through holes. And how does it behave? It behaves as if bounced or squeezed or bent. We learn nothing, we merely cause events.’ I bent closer to him, waving my finger to keep his attention. ‘Has it occurred to you that sundials do not measure time, but create it?’ It had not, I saw. Time,’ I said,’is actually a thing, like porridge.’ I folded my arms and beamed at him, triumphant. The left side of his mouth twitched very slightly. He withdrew.”
From The Wreckage of Agathon, John Gardner – 1970
Getting microscopic with some little green friends. Co-starring Tardigrades (water bears)
Ferrofluid is a liquid that becomes strongly magnetized in the presence of a magnetic field. A grinding process for ferrofluid was invented in 1963 by NASA’s Steve Papell as a liquid rocket fuel that could be drawn toward a pump inlet in a weightless environment by applying a magnetic field. Ferrofluids are colloidal liquids made of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid (usually an organic solvent or water). Each tiny particle is thoroughly coated with a surfactant to inhibit clumping.
When a paramagnetic fluid is subjected to a strong vertical magnetic field, the surface forms a regular pattern of peaks and valleys. This effect is known as the Rosensweig or normal-field instability. The instability is driven by the magnetic field; it can be explained by considering which shape of the fluid minimizes the total energy of the system.
From the point of view of magnetic energy, peaks and valleys are energetically favorable. In the corrugated configuration, the magnetic field is concentrated in the peaks; since the fluid is more easily magnetized than the air, this lowers the magnetic energy. In consequence, the spikes of fluid ride the field lines out into space until there is a balance of the forces involved.
At the same time, the formation of peaks and valleys is resisted by gravity and surface tension. It requires energy both to move fluid out of the valleys and up into the spikes and to increase the surface area of the fluid. In summary, the formation of the corrugations increases the surface free energy and the gravitational energy of the liquid but reduces the magnetic energy. The corrugations will only form above a critical magnetic field strength when the reduction in magnetic energy outweighs the increase in surface and gravitation energy terms.
Ferrofluids have an exceptionally high magnetic susceptibility and the critical magnetic field for the onset of the corrugations can be realized by a small bar magnet. – Wikipedia
A fascinating glimpse at the first Americans via genetics. They crossed the Bering Strait and shot off in all directions. A body from Nevada turns out to be very closely related to a body found in Brazil, across the equator…a few hundred years later. Close relationships were found between people who lived 10,000 years apart.
Crossing From Asia, the First Americans Rushed Into the Unknown
By CARL ZIMMER November 8, 2018
Three new genetic analyses lend detail, and mystery, to the migration of prehistoric humans throughout the Western Hemisphere.
Some early peoples came 20,000 years ago and died out, their DNA never found again. Some stayed in Alaska or doubled back to it later, apparently soured on the American dream. This article describes the adventure and sweep of this virtual gold-rush of a migration.
A ‘star drop’ refers to the patterns created when a drop, ﬂattened by some force, is excited into shape mode oscillations
Abstract: “These patterns are perhaps best understood as the two-dimensional analogs to the more common three-dimensional shape mode oscillations. In this ﬂuid dynamics video, an ultrasonic standing wave was used to levitate a liquid drop. The drop was then ﬂattened into a disk by increasing the ﬁeld strength. This ﬂattened drop was then excited to create star drop patterns by exciting the drop at its resonance frequency. Diﬀerent oscillatory modes were induced by y varying the drop radius, ﬂuid properties, and frequency at which the ﬁeld strength was modulated.”
“Shape oscillation of a levitated drop in an acoustic ﬁeld,” by W. Ran & S. Fredericks (Clemson University, Department of Mechanical Engineering)
These images were taken with a Scanning Electron microscope (SEM). The surface of a specimen is scanned by a beam of electrons that are reflected to form an image. Color is added later.
“Plenty of Room at the Bottom” is the title of an article written by the American genius, Richard Feynman in 1959. He worked on the Manhattan Project that delivered nuclear weapons to our military before the end of World War II. In the 1980s he was the scientist who figured out why the space shuttle Challenger exploded. In “Plenty of room at the bottom” he visualized the core ideas of Nanotechnology 2 or 3 decades before it became a widespread big idea.
“It is a staggeringly small world that is below. In the year 2000, when they look back at this age, they will wonder why it was not until the year 1960 that anybody began seriously to move in this direction.” Richard Feynman
We’re talking about a bustling industry where objects are measured in nanometers and micrometers.
- A nanometer =1 billionth of a meter and is represented by the symbol ‘nm.’. A sheet of paper is about 100,000 nanometers thick.
- A micrometer = 1/millionth of a meter (symbol: μm) A sheet of paper is 70 to 180 μm thick.
- One millimeter is equal to 1000 micrometers or 1000000 nanometers. A millimeter is equal to approximately 0.039370 of an inch. (mm)
In this video, we begin focused on a shrimp at a scale of 1 mm. We zoom down and in toward the top of the head where we see a microscopic sea plant, which eventually fills the screen. We close on a single bacteria, atop the seaweed zoomed from 1mm to 0.5um.
The remarkable chain drive below was built by the Department of Energy’s Sandia National Laboratories. The distance between chain link centers is 50 microns. The diameter of a human hair is approximately 70 microns. This is one example of thousands of separate projects and experiments laying the foundation of Nanotechnology.
A cuttlefish transmitting social information via pattern and color change. Apparently, this display means he’s really pissed off. Watch till the end and you’ll be in no doubt.
All cephalopods; cuttlefish, squid, and octopus use the same remarkable technique to communicate among their kind and camouflage themselves.
Close up of a squid’s color-changing cells called chromatophores. Amazingly these cells blend shades to create colors outside their individual range much as we can blend red, green and blue to create any color. Odder still, all cephalopods appear to be color blind.
Finally, here’s an octopus giving a practical demonstration of using chromatophores for camouflage.