This edition will bring us to the end of letter ‘E’, so, let us get on with the day’s business before our attention is diverted elsewhere.

Element: A substance composed of atoms having an identical number of protons around each nucleus. Carbon, hydrogen, and oxygen cannot be broken down into more fundamental substances. There are more than 100 known chemical elements, a few of them man-made.

Chemical compounds are formed when atoms of different elements are bound together into molecules. Everything, including you and me, are made of atoms. Those with flesh and bones are simultaneously made up from muscles, bone and tissues, which in turn are made from various atoms and molecules.

A chart of chemical elements that displays them in horizontal rows according to atomic number and in vertical rows according to similarity of the structure of their atoms, is called a Periodic Table.

Elementary particle: A subatomic particle, often regarded as irreducible constituent of matter, is often called a fundamental particle. Both of the above details are essential to the physics and chemistry of the universe. The higher you go into astronomy, or astrophysics (or physics at school), you will need to know more about them. Elementary particles are also called fundamental particles.

Elliptical: It refers to a shape like that of an ellipse, or a squashed or an elongated circle. Well, sort of. In other words, a shape that is not a perfect circle but rather squashed, or, a stretched sort of circle. The orbits of all the nine planets that revolve around the Sun, or most comets and many of the 100 or so moons are in an elliptical shape.

Energy: The potential for work. It can be represented in different ways: energy by its motion is called kinetic energy; position: potential energy; or by its mass. Einstein proved (1925) that mass and energy are equivalent (E = mc2), and a small amount of mass can contain an enormous amount of energy. Energy, again is a long and complex matter, but not difficult to understand. More about it later.

Equinox: A result of the Earth, diurnal (daily) motion about the Sun. Two times during the year (March 21 and September 22)when the length of day and night are equal. On these dates the relative position of the Earth to the Sun is such that the tilt of the Earth is nullified, and the same amount of sunlight falls on both Northern and Southern Hemispheres, i.e. when the Sun crosses the celestial equator. They are called the vernal equinox ( March), and the autumnal equinox (September).

Escape velocity: As you know already, it is the speed that must be attained by a moving body to break free of another body to escape (let us say) the pull of that body/planet. Rockets and spacecraft, or whatever else, must achieve high speeds to break free of that body’s gravity in order to be launched into space.

For instance, at a high speed of 20,000 miles per hour, it will only go into the Earth’s orbit but not into space. To do that, it will have to go faster, i.e. 25,000 mph, or 40,000 kph. Earth’s escape velocity is 11.3 km per second. Escape velocity on planet Jupiter is a whopping 134,548 mph. Compare that to the speed of a .22 rifle: 886mph!

Expanding universe: Edwin Hubble (1889-1953) is the one who postulated in 1929, this unique concept that galaxies were receding from Earth, and from each other, at a constant (but tremendous) speed. And that there were more galaxies besides our own. The great American astronomer is highly respected for his back-breaking work and the great observatory is named in his honour.

His discovery evidently proved that the universe is not limited or confined in any way, but is expanding ever since the event of Big Bang many billion years ago. In fact, it has been moving non-stop, first at nearly the speed of light, but has slowed down considerably in these rowdy years. The galaxies are still moving at a tremendous speed of many thousand miles per second, carrying all their stars and whatever else with them, albeit at considerably slower speeds.

When Hubble came to this conclusion, it naturally transpired that if the galaxies were moving away from each other uniformly, and irrevocably, then there must have been a time and space (place) when they would culminate or converge at a single spot, or the beginning. Hence the Big Bang. More about it when it is time to do so.

Extraterrestrial intelligence: Are we alone in the universe?

From a close study of life, and then intelligent life, the answer appears to be “No”. Many scientists have tried to prove this and some of them have even worked out the number of galaxies that may harbour life of one kind or another. Carl Sagan is one.

But in their enthusiasm, and despite their extraordinary knowledge, they have overlooked one vital aspect or another. I will present this view at the end of this discourse.

Some think that there are many, countless in fact, planets that are located at a suitable distance to their parent star and have lived long enough to nurture life of some kind, that there should be millions of them in the universe. Although it has been established beyond doubt that there could be many factors for their origin and proliferation which may be conducive to life of one kind or another, but none has been found as yet. Also, they agree that a civilisation that attempts to get in touch with us is, in all likelihood, far more advanced than us. And they believe that any place rich in oxygen, nitrogen and the like is a strong candidate for profusion of life.

Now my promise to you. There can be no life for trillions of miles around and next to the nucleus of a galaxy (and all have them) owing to a temperature exceeding millions of degrees. Far too hot for any life to emerge. Thus is gone about 25-30 per cent of the galaxy. That leaves us with 70 per cent. In this region are many different kinds of stars, either double or even triple, then those surrounded by the dark matter, and many other variables. Thus we are left with a small (yet a significant number, I admit) of stars that still qualify for our debate. We mustn’t forget that many planets are either too close or too far from the Sun to harbour any life, as in the case of our own planetary system.

Published in Dawn, Young World, April 16th, 2015