There’s a great segment in Douglas Adams’s Mostly Harmless, the 5th book in the ever-increasingly misnamed Hitchhiker’s Guide to the Galaxy Trilogy, about the limitations of human perception.  In it, the latest version of the eponymous Guide is an intelligent cyborg-type creature resembling a bird, and it tries to explain the nature of reality by shining lights into a driving rainstorm on a dark, dark night.


Heart and Soul Nebulae, visual/infrared mosaic (NASA)

A beam of light shining through rain and fog appears to be a solid shaft.  A beam moved rapidly back and forth becomes a plane, shaped like a fan.  Moved in a circle, the beam creates a solid cone.  And so on.

Using this analogy, Adams makes the point that the reality of the rain is constant in all three examples.  Just because we can’t see it doesn’t mean it’s not there.  On the other hand, the shaft, fan, cone and other shapes are tricks of our perception.  Seeing them doesn’t make them real – they’re literally tricks of the light.  An infrared beam creates a shape just as real, but of course that’s completely invisible to our limited human sensors.

This discussion has always resonated with me, on both a literal and figurative sense.  The simple truth of it – that our perception and understanding of the world is only as good as our very limited sensors – is important to remember.

PIA21474-CrabNebula-5Observatories-TextFor example, we can only see a tiny piece of the electromagnetic spectrum.  Astronomy is a much broader, richer pursuit when explored beyond the limitations of our own eyeballs.  My sons recently got the chance to take a field trip to the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, where they got to use one of the telescopes to take measurements of hydrogen emissions in the main disk of the Milky Way.  My best guess, based on the coordinates, is that the boys were looking at the Heart and Soul Nebulae, in Cassiopeia, which is a large hydrogen emission nebula that glows red in the visible spectrum – and per their demonstration, has clear hydrogen emission


Green Bank Radio Telescope, National Radio Astronomy Observatory, Green Bank, WV

lines in the radio spectrum as well.  Studies with X-rays, infrared, ultraviolet, and microwaves have given us amazing insight into the nature of the universe – though I still appreciate the beauty of the visual spectrum to false-color images or lines on a graph.

This richness extends to the natural world closer to home as well:  Bees, birds, and fish often see in ultraviolet.  There are patterns on flowers that reflect the UV spectrum, producing markings like landing aids for bumblebees, but that are totally invisible to us.  Elephants communicate, in part, using infrasound – extremely low-frequency sound waves that travel through the ground for miles, and can be “heard” through the animals’ feet.  Whales and bats use a wide variety of acoustic signals, many of which are well above our range of hearing.  Trees communicate with each other using chemical warnings that we are oblivious to (though, we CAN sometimes detect them through our sense of smell, and just don’t interpret them the same way).  And speaking of smell, many animals perceive the world as a palette of chemical signals that paint a rich picture that we simply are not equipped to know.

Arizona_bark_scorpion_glowing_under_ultraviolet_lightSome of these things, we’re just learning – for example, a recent study indicates it is very likely that birds can literally see magnetic fields (this is cool enough I’m going to devote a post to it in the near future).  Others we’ve known about, but not understood how other organisms use the information, if at all – we still don’t know, for example, why scorpions glow in UV light.

Some things we’ve used to advance science and ultimately, help ourselves – there’s a nice trick whereby reflections of certain combinations of red and near-infrared light off of green plants gives a strong indication of active photosynthesis, giving us the ability to “see” the difference between healthy and struggling plants that is normally invisible to us.  This has become a powerful, almost standard tool in agriculture, and in management of forests, wetlands, and other wild places, but it requires sensors that can register near-infrared, and computers to process the data and present it in the spectrum we CAN perceive. One wonders, are there animals that can see this directly?

The same is true figuratively and philosophically as well – the old adage to never judge someone until you’ve walked a mile in their shoes is really just a way of suggesting that we be aware of our own limitations in being able to perceive and interpret a situation, and being empathetic to other points of view.

Hemerocallis_fulva_2016_G1Ultimately, as smart as we are, we are all very limited by what we can see, feel, taste, touch, and smell.  Those of us who recognize how limited we are can readily embrace data from other sources, or be willing to listen to other points of view.  We are all stumbling through this world, oblivious to a lot of what’s actually going on.  That’s OK to a point, as we are certainly to be excused for not noticing things we physically can’t detect.  However, it’s hard to forgive ourselves for continuing to believe that we know all we need to, or that our limited perception of reality is the only one that matters.  We’ve done a lot of damage to the planet, our wild cousins who share it with us, and to each other, by being blissfully (or willfully) ignorant of just how complicated the interactions between pieces of our ecosystem truly are.

We can get by in this world without removing all of the filters that we’re born with.  But with 7+ billion people trying to share this little orb, it is increasingly important that we recognize those filters exist, and that all is not necessarily as it seems.  Just as in Douglas Adams’s example, the rain is there, even if we can’t see it, and sometimes the things we swear are real are just a trick of the light.  It’s critical that we ask questions, apply skeptical scientific rigor, and think hard about what we think we know.

Get Out There

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