Entertaining and Educational
If you haven't heard them, I highly recommend six lectures by Richard Feynman called Six Easy Pieces. It's a series of introductory physics lectures he gave at Caltech to incoming freshmen. The problem was whether to teach physics in the classical sense (you know, Newton) and in later classes introduce the concepts of Einsteinian relativity and quantum mechanics that change the picture of how physics works or to introduce the currently accepted picture of physics from the get-go.
So they asked Professor Feynman if he would give a series of lectures and thankfully these were recorded on reel-to-reel tapes that languished in a basement until somebody discovered them and digitally cleaned them up and made them available to the general public. The 6 1-hour lectures are available on CD or antiquated cassette tapes (which I bought for $10 on eBay).*
He really has a way of explaining things with ordinary language and analogies. He said that if an orange were the size of the Earth, each of its atoms would be the size of an orange. I heard he once got irritated when someone used the phrase "acoustic reflection" and asked why not use the word "echo"?
There are a few dull spots, such as when he sets out to prove there can be no perpetual motion machine. I take it on faith that if there is friction, there is bound to be less than 100% efficiency in any machine.
But the high notes he hits will stimulate your imagination and leave you with a deeper understanding and appreciation for the wondrous subtle interconnections and interactions all the way from the gravity evident across unimaginable distances in a spiral galaxy down to subatomic forces.
Also available from Audible last time I checked. They offer extended free samples, though I don't know what part they offer as a sample.
Definitive answers to two unanswerable questions
I read that a space probe landed on Mars. It may find water or evidence of water from the past. It may turn out that those canals on Mars (which if I remember correctly are a mistranslation of the Italian cannali or channel) really once were flowing waters.
To the question "is there life outside of earth?" I will give you a definitive answer: Yes.
In astronomy class at Valley Junior College, I learned that by looking at the spectra (you know, spectrums) of light coming from a distant star run through some instruments, they can tell what elements are present in what proportion and even determine an approximate temperature for that star. And it turns out the same basic elements (you know, the periodic table) are present and form the stuff of the visible universe.
So if hydrogen and oxygen and nitrogen and carbon are present everywhere, and have the same characteristics and react the same way independently of whether on Earth or anywhere else, the way I figure it the simple combination of dihydrogen oxide is bound to be all over the place. And chains of carbon forming organic molecules are bound to occur under a variety of conditions.
So I contend that there is water and organic material (life) beyond our tiny sloshing planet.
Do I believe in extraterrestrial beings?
Let me put it this way -- the chances that a single molecule would eventually become a conglomeration of specialized cells that eventually would have two limbs for movement and 2 for grasping with five fingers (or 2, 3, or 4) with a bulbous head that includes 2 eyes and a mouth and that the same pattern would occur independently from a single cell in a galaxy far, far away would be an inconceivable coincidence. Sorry. I assume that those drawings or anecdotes of extraterrestrial visitors are merely projections that someone's mind has formulated. Even if they believe it.
So my definitive answers are: yes, there is life elsewhere in the universe and no, there are no reptilian-featured alien visitors. I may be wrong, but my answers are definitive.