The Davey Dialogues - An Exploration of the Scientific Foundations of Human Culture. John C. Madden
In the circumstances, I would bet money that while the outer boundaries of our powers of observation and comprehension seem to be the boundaries of the universe we inhabit, it is likely that there are now, have been and will be other universes. But let’s be clear that this is not a scientific observation. In my case, it is based in part at least, on my unprovable, but for me very stimulating and real, conversations with Davey.
– In spite of Arthur Eddington’s unease, there was at least one very significant member of the cheering section for Hubble and his findings. Albert Einstein had discovered that his General Theory of Relativity predicted that the universe was not in a stable state but was either expanding or contracting. This was directly counter to the generally held belief in a stable universe prior to Hubble, a fact that had persuaded Einstein that his theory must be wrong. He therefore introduced a cosmological constant whose magnitude was calculated to ensure stability of the universe. Six years later when he first heard of Hubble’s discoveries, he revised his equations to remove the constant and referred to his earlier introduction of the constant as the biggest blunder of his life. He even made a special trip up Mount Wilson to thank Hubble for his work. By that time he had already taken pains to give special recognition and thanks to Friedmann and Lemaître.[17]
It is perhaps ironic that the discovery in 1998 that there is a small but continuous acceleration in the rate at which the universe is expanding has caused a revival of Einstein’s cosmological constant. The leading explanation for this surprising discovery is that the universe is suffused with a constant (but so far undetected) energy filling all space homogeneously. This energy has been labelled “dark energy”, and can be conveniently thought of as a cosmological constant. If you find this confusing, don’t be discouraged. There will likely be more changes coming soon. These are exciting times in the field of cosmology.
Apparently Davey, too, had noticed the anomaly. Finally, a response!
– I find it very interesting that even very distinguished scientists such as Einstein seem to incorporate new variables into their theories just to make them fit the facts, without, it seems, any real notion of what in the physical world that particular variable represents. There seems to be a lot your physicists don’t know about your surroundings.
– On the contrary, I think you should be amazed at how much they do know. It has taken us centuries to accumulate the knowledge we have of our environment, but in most cases we are now able to understand and to forecast what is going on in our universe to an astounding degree of accuracy. For instance, the Standard Model theory of particle physics was able to forecast not just the existence of new particles as yet undiscovered, but also predicted their mass correctly to better than four decimal places, as measured after experimental physicists had searched for and found the particles. When a theory is able to make predictions such as these, one has real confidence that the theory is on the right track.
– I suppose you may be right. But what exactly is the Standard Model of which you speak so highly. I don’t recall that you have mentioned it before.
– It is an intellectual triumph – a masterpiece of co-operative scientific endeavour stretching over sixty years or so. The model encompasses a theory of almost everything in that it describes all known forces except the force of gravity, and successfully predicts the properties of all known sub-atomic particles.
– What you seem to be telling me is that this great model of yours describes and predicts a lot of things, but it is of little, if any, help if we want to understand your universe, where the force of gravity reigns supreme.
– There is an element of truth to what you say, I conceded, but you should know that the nuclear reactions taking place in the billions and billions of stars in the universe are very accurately predicted and described by the Standard Model. That said, the Standard Model, while useful in providing an understanding of the life and death of stars, is currently of little help when it comes to understanding the overall structure and history of our universe.
Davey seemed ambivalent. It was somewhat annoying to realize that he might know far more than I was giving him credit for. Perhaps he knew the solutions already to some of the tough questions the cosmologists were tackling. I planned to talk a bit about these questions in a future dialogue, and I wondered if I could trick him into showing his hand at that time. In the meantime, I returned to the subject at hand.
– As you can see, the numbers associated with the study of astronomy are, well, astronomical! It takes our sun 250 million years to complete an orbit about the centre of our galaxy (by comparison, dinosaurs are thought to have appeared on Earth only about 230 million years ago). As previously mentioned, the average galaxy is estimated to contain one hundred thousand million (~1011, or 1 followed by 11 zeros) stars, and astronomers believe that there are well over a billion galaxies in the universe! Over the past decade, it has been possible to observe the effects of large planets orbiting nearby stars. While not all stars have planets, clearly some of those that do, like our sun, have several planets.
At this time I know of no reliable estimate of the likely number of planets in the universe. It may be of the same order as the estimated number of stars (i.e. ~1020), but even a number one thousand times smaller is still unimaginably large. Similarly, it is hard to find an estimate of how many, out of the total number of planets, could support life, but it would be exceedingly rash to imagine that our Earth is the only one amongst this huge number of candidates. A similar line of argument makes it seem extremely likely that more than one of these remote planets is home to life forms that are at least as intelligent as we are.
Most of us humans are still inclined to consider ourselves the wisest and most intelligent species in the universe. If there is a superior species one might reasonably expect that it would have been in touch with us by now, and left us with firm evidence of its (superior) existence. But is this really true?
Davey, you could really help me here. You say you don’t even come from our universe, but rather from another universe altogether. Assuming that this is true, and that you really have wandered about our universe in ways we are not yet capable of, perhaps you could let me know what you have found in the way of other life forms in our universe and perhaps also, by the way, what you know about life forms in your own universe.
– Sorry, Peter. I thought I had already explained to you that I cannot possibly answer such questions without first understanding whether what I say could unduly harm life in your universe. I understand your impatience, but you will just have to be patient for the time being.
– It’s all very well for you to ask for patience. You need to understand that I have to work hard to pull together the information you have asked for. Thus far I have received precious little from you for all my effort.
– I think you know that you have my sincere thanks as well as my appreciation. I was given to understand that most humans appreciate such gifts.
I rolled my eyes. As I did so I realized that he could not see the gesture. This realization led me to wonder how often he was misled by what he heard, as it would have been much more difficult for him to detect sarcasm than for the rest of us in the circumstances.
– Do please continue, Peter. What you are describing is a rather intricate method for determining the extent and nature of your universe. I admit that it seems rather awkward and unnecessarily involved to me, but given that you lack the tools that I have to understand my universe, I have to take my hat off to your scientists for what they have accomplished – and I am very interested to see how your story will end!
– All right. I suppose I should continue, at least for the time being.
In an attempt to introduce some order into what can at best be described as a highly speculative subject, Frank Drake, a physicist at the University of California in Santa Cruz, introduced in 1961 what has become known as the Drake Equation. (Carl Sagan, a well-known physicist and science writer of my time, gave the Drake Equation considerable prominence, to such an extent that it is also known as the Sagan Equation.)
Figure 4.3 – The Butterfly Nebula. This spectacular photo (NGC 6302) was taken in 2009 using the upgraded Hubble Space Telescope. It is representative