Things We Can’t See

When you think about it, there is a great deal out there that we can’t see.

Our eyes only respond to a very narrow range of electromagnetic radiation.  The following diagram demonstrates just how narrow our range of vision compared to the overall electromagnetic spectrum.


So we can’t see anything that generates or reflects wavelengths equal to or longer than infrared, as the following image demonstrates.  Even the Hubble Space Telescope can’t see the distant infrared galaxy that the Spitzer Space Telescope can see with its infrared sensors.



And we can’t see anything that generates or reflects wavelengths equal to or shorter than ultraviolet, as the image from NASA demonstrates at left. Only instruments with special sensors that can detect ultraviolet or x-rays can see some of the objects in the sky.

Of course, we can’t see things that are smaller in size than about 40 microns, which includes germs and molecules.



We can’t see things that are camouflaged by technology, such as the Mercedes in the following picture.


Sometimes, it isn’t our eyes that can’t sense something that is right in front of us, but rather, our brain.  We actually stare at our noses all day long but don’t notice because our brains effectively subtract it out from our perception, given that we don’t really need it.  Our brains also fill in the imagery that is missing from the blind spot that we all have due to the optic nerve in our retinas.

In addition to these limitations of static perception, there are significant limitations to how we perceive motion.  It actually does not take much in terms of speed to render something invisible to our perception.

Clearly, we can’t see something zip by as fast as a bullet, which might typically move at speeds of 700 mph or more.  And yet, a plane moving at 700 mph is easy to see from a distance.  Our limitations of motion perception are a function of the speed of the object and the size of the image that it casts upon your retina; e.g. for a given speed, the further away something is, the larger it has to be to register in our conscious perception.  This is because our perception of reality refreshes no more than 13-15 times per second, or every 77 ms. So, if something is moving so fast that it passes by our frame of perception in less than 77 ms or so, or it is so small that it doesn’t make a significant impression in our conscious perception within that time period, we simply won’t be aware of its existence.

It makes one wonder what kinds of things may be in our presence, but moving too quickly to be observed.  Some researchers have captured objects on high-speed cameras, for which there appears to be no natural explanation.  For example, there is this strange object captured on official NBC video at an NFL football game in 2011:  Whether these objects have mundane explanations or might be hints of something a little more exotic, one thing is for certain: our eye cannot capture them.  They are effectively invisible to us, yet exist in our reality.

In my next blog we will dive down the rabbit hole and explore the real possibilities that things exist around us that we can’t even touch.

Yesterday’s Sci-Fi is Tomorrow’s Technology

It is the end of 2011 and it has been an exciting year for science and technology.  Announcements about artificial life, earthlike worlds, faster-than-light particles, clones, teleportation, memory implants, and tractor beams have captured our imagination.  Most of these things would have been unthinkable just 30 years ago.

So, what better way to close out the year than to take stock of yesterday’s science fiction in light of today’s reality and tomorrow’s technology.  Here is my take:


Wacky Ideas from my Past – #1 The Invisibility Cloak

When I was a geeky teenager, I remember dreaming up these wild inventions that I though could revolutionize the world in some way.  Since that was 30 years ago, I thought it might be kind of fun to take stock of the likelihood of these ideas it today’s time.  Please try not to laugh.  Here was idea #1 – The Invisible Cloaking Device…

My thought was this – how cool would it be to be somewhere and put on a jacket and just become invisible.  Of course, the back pages of Popular Mechanics always had see-through glasses but of course, they were a gaff.  But I wondered if the cloaking concept could really work.  I didn’t see why not.  The way I figured it, if they could make transistors that were pretty much microscopic, and LED’s that were based on transistors, why not little cameras that were just as small?  All you had to do is put zillions of these cameras all over your cloak as well as zillions of LEDs.  But the LEDs had to be able to generate any color of light.  And each point of the cloak would have many cameras pointing in each direction, the signals of which were collected at a central computer.  The computer would figure out what part of the cloak was at the exact opposite position for each camera and each direction of view.  And so, that signal would get routed to the LED so as to generate the image that was the same as if you were looking through the cloak.  An engineering nightmare to be sure, especially in determining the position of every point of the coat.

So imagine how excited I was in 2006 when I first heard of experiments being done with cloaking devices.  Unfortunately, however, the technology is still woefully weak.  As shown in the figure below, you have to put a camera directly behind the subject and a combiner device between the viewer and the subject and it only works in one direction.  So, nobody is going to get fooled any time soon.

invisibility cloak

But still, the resulting effect is kind of cool.  See below…

invisibility cloak

So when will we have true invisibility?  I have seen projections of 10-20 years for single color with a cloak of a well-defined shape.  “Sometime this century” for a Harry Potter type invisible cloak.  I think that nanotech will facilitate the process by enabling microscopic devices that can image in all directions and are self aware of their position.  So, I say…