I have used this photo because the football referee does feel grounded and hence offers an experience of gravity (Photo: MC)
I think I have reached a stage in life where there is no difference between comprehension and incomprehension. Most concepts in physics, which I thought I comprehended in my younger years, are now safely beyond my comprehension. Gravitation is one such idea. I have always been fascinated by it but with advancing years it makes progressively less sense to me. I think I just don’t get it any more.
To be sure, my not getting it is not at the level of a fourth grader not getting it but not getting it in all its philosophical dimensions. Albert Einstein’s idea of curvature in spacetime caused by massive objects is exquisitely picturesque to me but I can no longer comprehend it. As I have often said the words strung together as part of sentences to explain his theory do make sense to me both individually and collectively but then at the end of it the final conclusive meaning eludes me.
My incomprehension about gravitation as a scientific concept does not prevent me from occasionally interpreting its philosophical and physical manifestations. For instance, I wrote the following as recently as May this year:
Gravitation as a natural phenomenon has been on my mind for as long as I can remember. In particular, I keep revisiting how gravity is at the heart of everything we are and the universe is.
Strangely, it is for the third time in as many years that I am thinking of gravity roughly around this time of year. It was in March, 2011, after the Japanese earthquake and tsunami, and again in April, 2012 that I wrote about gravity. This time it was triggered yesterday while watching my daughter Hayaa’s weekly soccer game; especially when I saw this assistant referee against the backdrop of the overcast sky above and the fresh green grass below. I was sitting in my partially broken deck chair on the sideline.
The entire activity of children running and kicking the ball, the ball moving, rising and falling, self in somewhat wobbly chair and the assistant referee with his feet firmly planted on the ground, everything was one of the millions of manifestations of gravitation.
Everything on Earth has evolved in response to the particular intensity of her gravity. On Mars, for instance, we would have to evolve in response to a gravitational force 62 percent lower than here. Presuming for the sake of illustrating the point that life could have still evolved and thrived on Mars, it would be so very different. Martians might still have played football (as in European football played with feet) but it would have been 62 percent slower than on Earth. Of course, the Martians would not have felt the slowness of their football because for them that would be the natural speed and their only reference point. Our understanding and experience of things are necessarily situational.
A vast majority of us, who would never get to enjoy interplanetary travel, cannot possibly know how it would feel to be on a planet which has 38 percent of our gravity. Even the expression “The gravity of the situation…” would have meant something different. An earthling visiting Mars would perhaps say, “The 38 percent gravity of the situation…..” As always, I digress but then an earthling would digress on Mars because of its lower gravity.
Am I glad that gravitation exists? Mostly yes, but I am equally curious about what if there were a sudden, albeit a slight variation in our terrestrial gravity.What if gravity could leak like a liquid?
The National Space Biomedical Research Institute (NSBRI), established by NASA, makes some fascinating points about the effects on human body of varying gravity. It talks about the effects of changing gravity on bones, muscles, spine, cardiovascular systems, inner ear and balance and sleep.
One was taught a long time ago that it is our inner ear that is particularly sensitive to gravity and helps us keep our orientation. Here is how the NSBRI explains: “On Earth, a complex, integrated set of neural circuits allows humans to maintain balance, stabilize vision and understand body orientation in terms of location and direction. The brain receives and interprets information from numerous sense organs, particularly in the eyes, inner ear vestibular organs and the deep senses from muscles and joints. In space, this pattern of information is changed. The inner ear, which is sensitive to gravity, no longer functions as designed. Early in the mission, astronauts can experience disorientation, space motion sickness and a loss of sense of direction. Upon return to Earth, they must readjust to Earth’s gravity and can experience problems standing up, stabilizing their gaze, walking and turning. These disturbances are more profound as the length of microgravity exposure increases. The changes can impact operational activities including approach and landing, docking, remote manipulation, extravehicular activity and post-landing normal and emergency egress.”
So as I sat on the sideline yesterday, somewhat disinterestedly watching the game but thinking more about gravity, it was entirely unique to my being on this particular planet. My predilections, predispositions, perspectives and perceptions would have been radically different even on our nearest celestial body, the dusty desolation we call Moon. That’s because my brain would have formed differently in keeping with the gravity there. By the way, the lunar gravity is a mere 16.7 percent of Earth’s. My point again is our certitudes become invalid even on our nearest neighbor. So next time you clear your throat and adjust your collar to hand down what you believe to be a grand universal pronouncement, take a pause and preferably give up the idea.
I now struggle with even the difference between the Newtonian idea and Einsteinian idea about the direction of forces that act on us as we feel grounded to the Earth like the referee is in the picture above. The Newtonian idea was that just as we are being pulled toward the Earth, the Earth is also being pulled by us. The Einsteinian idea says we are being pushed up even as we are pushing back on the Earth.
While I am at it I might as well mention the fallacy of straight lines. Since we all lived in curved space there are no real straight lines except that given the massive scale of the spacetime curve we may treat relative short lines between any two points as straight for all practical purposes. (Just about now I can see you scratching your head and saying “What is this man talking about?”) That incomprehension is precisely my point.
In my case comprehension and incomprehension about everything constantly cancel each other out in the final result, although at specific points in time one may be greater than the other.