When I stop and think about it, it never ceases to amaze me that radio waves, infrared light, which we experience as heat, x-rays and gamma-rays are all the same fundamental physical phenomenon – light, or electromagnetic radiation. The thing that distinguishes these different kinds of light is the wavelength. Think of waves on the ocean, and taking out a ruler and measuring the distance between crests – that is the wavelength, only for light we are measuring the distance between ripples in electric and magnetic fields. For radio waves the wavelength is the size of a building, for X-rays it is the size of an atom. Astronomers use light of all wavelengths to understand the nature of the universe.
X-ray astronomers use telescopes that collect the same kind of light that your dentist and doctor use to see through your skin to study some of the hottest, densest and most extreme environments in the universe. X-rays are emitted from regions where material is heated to 10 – 100 million degrees Celsius, from places where particles are accelerated very close to the speed of light, and from intense cosmic explosions that are the death cries of massive stars. Regions that glow in X-rays range from the largest objects in the Universe that are held together by gravity, called galaxy clusters, to the most compact objects, like black holes and neutron stars.
X-rays are electromagnetic radiation just like radio waves, optical and infrared light. X-rays have a wavelength the size of an atom, and must be observed from above Earth’s atmosphere by telescopes such as Chandra, XMM-Newton and NuSTAR. Credit: NASA.
We all know about silk and its smooth and uniquely beautiful apparels but know very little all processes that help transform tiny butterfly’s eggs into silk-based products. One of several important processes for obtaining long and high quality raw silk and sustaining high quality breeders is silkworm gender identification. It is accomplished by asking well-trained officers to visually inspect at the abdomen segment of the silkworm pupae. Although this non-destructive approach is cost effective for several developing countries, it is very time consuming and affects the eye sight of the officer.
Rather than investigating vulnerable parameters of the silkworm such as its mass and shape or utilizing expensive equipment such as optical spectrometers and magnetic resonance imaging systems, a very simple optical means via penetration of light through the silkworm pupa is exploited (1-3). Below figure shows that the image contrast of an important organ of the female silkworm pupa is clearly observed under the penetration of red light. This simple approach is actually similar to a familiar activity where we illuminate light from a light emitting diode on one side of our fingertip and see light coming out from the other side.
Image of a female silkworm pupa under (a) typical visual inspection and (b) penetration of red light. Credit: Sarun Sumriddetchkajorn.
There are currently more “international days” than days in the year (approximately 400).
Each of these days is trying to raise awareness on important problems (diseases, human
rights, environment, etc.), or on even more important issues (“Go barefoot day”,
“Raspberry cake day”, etc.). Only at the highest level, can a topic be considered
sufficiently important to deserve a full year of celebration. This is why United Nations
supports between one and five “international years” every year. Different than the
selection of international days, the UN selection process is so rigorous that we can
trust every chosen topic to be essentially pertinent for Mankind. Through this selection
process, this year has been proclaimed “International Year of Light and Light-based
Technologies” (IYL 2015), but it is noteworthy that it is also the “International Year of
I am fortunate to be an active participant of IYL 2015, and in particular, to represent the
African Physical Society (AfPS) in many IYL 2015-related events. One of the questions I am
asked very often is “Why would such a year be important for Africa? Why do you think we
should pay attention to IYL 2015 while we are still struggling with very fundamental problems
like education, healthcare, and basic infrastructures, etc? ”
My answer is always simple: the economy.
When the spectrum of electromagnetic radiation we recognize as light enters the eye, it encounters a set of cells known as photoreceptors, activating and causing them to fire, sending electrical signals down the optic nerve and into the brain. This raw information is then processed and interpreted by a number of complex processes, the exact workings of which remain unclear. Yet there is little doubt. It is literally how we see the world.
It is this role of light – that of genesis, discovery, unveiling the new – that informs the practice of New Zealand multimedia artist, Kristin O’Sullivan Peren. As Peren herself notes, “you cannot see light unless there is darkness.”
Drawing on her history as a print maker, Peren’s recent personal work combines sculpture and light in a mesmerizing example of literal metaphor. The cast resin form of her installation Free Beauties pulses with the shifting light of hundreds of LEDs, their activation based on an algorithm inspired by the naturalist Sir Joseph Banks’ gathering of flora and fauna when he first arrived in New Zealand in 1769. The weeds collected from this exploration were pressed between the pages of Spectator Magazine, a critique of John Milton’s Paradise Lost, with this providing the basis for the algorithm – inviting the audience to consider, in the artist’s own words, “the search for the Modern Sublime”.
Ice cream with Free Beauties 2015 Earnslaw Park Queenstown ,New Zealand. Credit: Kristin Peren.
Whether walking down a city street near a crowded nightclub opening or pulling up to the parking lot at the local county fair, it’s probably a safe bet that you’ve seen those bright, white searchlights flitting across the dark nighttime sky – the outline of the light beam clearly visible as it reaches up to touch the bottoms of the clouds overhead. As a signal that can be seen far and wide, searchlights have a way of drawing you in to the main event. Hollywood producers certainly know this to be true. For example, the next time you sit down with a bowl of popcorn to watch a 20th Century Fox movie, note the searchlights scanning the hazy skies in the opening credits. Part of the reason searchlights are so captivating is that when we shine them up into the heavens, the light doesn’t just travel up to be lost into space – much of it is reflected by particles, clouds, and gases in the Earth’s atmosphere back down to the ground where we can see it.
Two lidar beams look up into the sky from the roof of the optical remote sensing laboratory at Montana State University in Bozeman, Montana, USA. The visible green laser beam is measuring the atmospheric profile of aerosols and clouds, while the invisible infrared laser beam is measuring water vapor. The lidars are in a laboratory on the top floor of the engineering building and transmit to the atmosphere through a roof port hatch. Credit: NASA/A. Nehrir.