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Welcome back, favorite readers. Unfortunately (or fortunately, depending on how you’re looking at it), I returned from a wonderful, week-long tropical vacation very late last night, and today I’m back in my windowless office with only the comfort of duct noise to soothe me. While the plaster walls are certainly taking my mind off the rain and the cold that describes today’s weather forecast back in Portland, my mind is quite irretrievably still on a Hawaiian beach, a fact which my boss is not particularly pleased with given the notebook full of work he tossed on my desk this morning.
What this means is that my grand plans for this week’s topic have sputtered and failed. I was hoping to focus on the world’s favorite childhood question: “Why is the sky blue?” The answer has a direct relation to the photograph on the right (taken on the last night of my trip), which displays a scene of recurring natural beauty that has caught the breath of human beings throughout history. While it might seem like an excuse to show off pictures from my vacation -- which it is -- it happens to be one of my all-time favorite topics in physics, and it has contemporary relevance regarding the ramifications of a dramatic spike in airborne pollutants that follows technological advancement and societal growth. However, it requires a full week’s worth of dedicated time and effort to truly do justice to, and I hate short-changing pieces that I’m passionate about. For that reason, I have chosen to forego it, so look ahead to an exciting Thursday next week!
If that isn’t enough to draw you in, then I will also include a brief spoiler as a replacement for this week’s full post. Upcoming in my topic queue is a discussion on the speed of light, and what its constant value suggests about time-travel, relativity, and planetary physics. Having paid homage to the world of the small, it seems only right to introduce you to the opposite end of the spectrum. However, before I delve into it, I wanted to give you an appropriate respect for scale, since it is necessary in order to appreciate one of the greatest challenges of modern scientific understanding.
When professors introduce the scale of the universe to students, they do so with a logarithmic system. In other words, rather than counting by the same increment each time (ones, tens, or hundreds), they increase the size of their jumps by ten times the previous increase. We start with one, then move to ten (101), then one hundred (102), then one thousand (103), ten thousand (104), and so on. Scientists call each jump an order of magnitude, which is just fancy-speak for powers of ten. We can also go backwards by using negative powers of ten, starting with one, then one tenth (10 -1), one one-hundredth (10-2), etc. Each jump gets its own special prefix like mega-, tera-, milli-, or nano-.
In previous posts, I have talked about electromagnetic radiation (aka light) while mentioning terminology like wavelength, frequency, and energy. In the same breath, I have attempted to distinguish between visible light and all other forms of electromagnetic waves while still underlining their family similarities. Every day we experience the human eye’s power to recognize differences in color, which is another way of saying that we can read and resolve a certain range of light types. What we see as blue is simply our eye putting a definition to light that has a wavelength of 450 nanometers (0.00000045 meters); red has a wavelength of about 700 nanometers. But there is a vast range of wavelengths that our eye cannot ever see, from one trillionth of a meter long up to thousands of meters long. Visible light represents only a tiny sliver of what is available. We are blind to most of our world.
This is just one example of how our experiences in daily life are limited to senses that only function over a small range compared to what is available. We have developed tools that allow us to visualize things that are much smaller or much bigger than we can conceive, but their range may be decisively limited by the laws of the universe. We usually build models of the very large or the very small to bring these scales to us, because the reality is rather disconcerting. We are moving through a very narrow spectrum of existence, with numerous dimensions that we simply cannot breach . In the same way that the human eye can only see color, it also has very restrictive limitations on what sizes it can comfortably understand.
There have been a number of brilliant, beautiful, and masterfully edited representations of these powers of magnitude, just to give people a sense of how vast the range of our universe is, and to conclude today’s short post, I will link to one in particular that I enjoy. It’s interactive via the slide-bar at the bottom of the video, and I encourage everyone to play with it until they develop a thorough appreciation that will support future topics. Come back next week with this understanding, and we’ll move on from there.
I know, I never said there would be homework. I’m sorry for those of you out there who feel deceived.
See you back again next Thursday. Email suggestions or requests to firstname.lastname@example.org!