All posts by StenBlog

Making Sense of the World

Ask just about anyone how many senses a normal human has and the immediate answer will be five: sight, hearing, taste, smell and touch. By the way, I always manage to forget that last one for some reason!

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The oldest mention of this particular list goes all the way back to the Hindu Katha Upanashad written in the 6th century BCE. Even Shakespeare mentions them as the ‘five wits’ in King Lear! But a lot has happened since way back when. The entire idea of ‘scientific research’ came into its own, and now there are a whole lot of other human senses that have been added to the classical mix we learn in grade school.

Sense Number Six: You can detect heat and the temperature of any object you touch or are placed close to. Your skin has thousands of little ‘receptors’ that individually detect the attributes of cold and warm.

Sense Number Seven: You can detect whether you are standing upright or lying down through the balance receptors in your inner ear, which are hollow loops filled with liquid. The movement of this liquid in each loop is sensed by neurons and tells the brain your head’s position in 3-dimensions.

Sense Number Eight: Pain is a sense that is not just the overloading of touch or pressure receptors in the skin. In fact we have three different groups of pain receptors that signal internal organ damage, external skin damage, or damage to our bones and joints.

Sense Number Nine: Another overlooked sense is proprioception: the ability for you to sense the orientation of your body and limbs in 3-dimensional space. Without this very important sense, you would not be able to walk, jump, dance, type at your keyboard, or a thousand other activities that make up your life.

Sense Number Ten: Chemoreception is the ability of your body to detect changes in the foods you eat, and signal the body to reject that food if it fails to pass certain internal tests. This sense can cause your stomach to contract, cause you to vomit, and cause changes in your vascular system,: ‘OMG I just ate rotten fish!’

Sense Number Eleven: Although not a specific cellular feature of the nervous system, every normal human has a perception of their place in time. Part of this is our 24-hour circadian rhythm, but through brain activity, we have a timing sense that allows us to sing, dance and play a musical instrument correctly. It also helps us locate ourselves in the present moment within our accumulated memories.

Sense Number Twelve: Outside versus inside. We have a unique sense of where our body ends and where the outside world begins. Without this, we would identify every sensory stimulus as originating within our body, and that our body has grown to encompass the entire physical world ‘outside’. More on this later!

Sense Number Thirteen: Friend versus Foe. Our cells have proteins on their surfaces that identify to our immune systems whether a cell is part of our own body, or is a foreign interloper.

If you think this range of senses covers all of the biological possibilities, there are many more senses that some animals have, and perhaps we also do at some very, very low level.

Sharks and some other fish can detect electrical fields with specialized receptors in their skin. Many animals can detect earth’s magnetic field and use this to navigate. Bees can detect polarized light, which they also use for navigation. The vomeronasal sense allows animals to detect the pheromones of other members of their species and use this to identify a mate in estrus, or members of their own clan. Plants can directly sense gravity and use this to help them grow upwards. Both animals and plants can detect slight changes in air moisture to precisely identify where a source of water is located.

The earliest known senses were developed by single cells to detect changes in various chemical concentrations in water – a potential food source. But by far the oldest sense among complicated organisms is vision. This particular sensory skill has been re-invented literally hundreds of times by evolution across millions of different organisms.

So there you have it. Senses are a brain’s way of detecting an organism’s place and situation in the physical world. Amazingly enough, human brains do not take-in all of the information generated by our senses. If it did, we would be in a near-constant state of epilepsy! So what our brains do is to actively suppress most of the sensory information our receptors generate before it even reaches our consciousness. In fact, if you were to look at the neural activity of the brain, far more neurons are devoted to the brain talking to itself, than checking on what’s happening in the outside world!

So what does the brain do with all of this information?

That will be the topic of my next blog!

Check back here on Friday, November 25 for the next installment!

The Universe and Etc!

Hi there!

It’s exciting to start a fresh new blog project. It’s kind of like your first day in class with a new pencil and a binder with blank sheets of paper. Even as late as graduate school at Harvard I always found that first day of class exciting and filled with such promise.

You have probably GOOGLEd me by now and discovered I am a professional astronomer and educator. No I am obviously not one of those famous ones you may know by name. There are thousands of astronomers and physicists in this country, many of them far more famous than I am, but chances are you have never actually met one. Even fewer people have astronomers as members of their families!

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So here I am, one of those back-roads professional astronomers who has also spent a lifetime studying space and delving deeply into the nuances of the physical world. If you decide to make it a habit of reading my blogs, you may be pleasantly surprised how a slightly different perspective might help you see the world around you a bit more clearly. I hope you will at least appreciate the connections that I see, and why they have been such a source of joy and wonderment to me all my life. As they say, it is not the destination that matters but the journey!

I have always been interested in science: the exploration of the physical world. My mother used to tell me that when she would take me out into the fragrant spruce forests surrounding my hometown Karlskoga in Sweden, she would always have to empty out the rocks in my stroller that I collected along the way. This evolved into a progression of interests leading to a passion for astronomy by 5th Grade.

But as I was exploring the hard facts and theories of astronomy and physics, it was hard for me to give up my interests in ESP and UFOs. For you see, well into middle school I used to plot the positions of UFO sightings on a map of the USA on my bedroom wall, and marvel at the descriptions of the many sightings reported in newspapers and magazines. By high school,  I was reading Carl Sagan’s ‘Intelligent Life in the Universe’, but I was also reading von Daniken’s  ‘Chariots of the Gods’ and Frank Edwards ‘Stranger than Science’. As a Junior in college, I had my own experience of sighting a UFO in the twilight sky.    I also developed an interest in ESP because my Swedish mother beguiled me with many family stories of spirit sightings and telepathic incidents during my early childhood. In high school, my friends and I conducted séances…which [fortunately?] failed, and I had my own experiences with family ghosts and inexplicable events.

Then something peculiar happened around age 23 when I was beginning my Senior Year at UC Berkeley working on my degree in astronomy.  By then, these interests in ESP and UFOs had subsided and simply vanished from the palette of issues I wanted to keep up with.  What had happened?

As I became more steeped in science, its history, its many spectacular successes, and endless rounds of homework to learn  physics from the inside out, I spent less and less time with ideas that entertained, but had far less substance and productivity to them. At some point, the hard data and objective mathematical rigor of science became a far more compelling story than the endless presentations of subjective evidence from ESP and UFO enthusiasts. It seemed to me  that there was not one shred of hard evidence about ESP and UFOs that could not be dismissed as wishful thinking, unsubstantiated anecdotes, statistical variation, or out-right fakery.

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In science, advances are made when data is obtained under controlled, repeatable conditions by parties whose only goal is to collectively create an accurate model of how the world works. I decided in college that this was drastically different from ‘ghost chasers’ and UFO hoaxers, who often flooded these subjects for fame and personal gain. But there was one subject area that I immediately gravitated to, that replaced all of these entertaining ideas: Brain research.

I am going to try to explain advances in our understanding of both the physical world and our mental world in a series of blogs that my non-scientist mother would have enjoyed reading. If you want more extensive details, you are free to GOOGLE the words and topics and look to other professionals for explanations who are also popularizers. I will recommend their insights and explanations as my blogs develop.

So where do we start?

Well, for my next few blogs, let’s begin with the brain and how we perceive and make sense of the world around us. That, after all, seems to be the biggest ingredient in creating a rational picture of the world around us.

It is also the biggest impediment!

Return here on November 21 for my next blog in this series!