Reflections on a Surprising Universe: Extraordinary Discoveries Through Ordinary Eyes
177
Reflections on a Surprising Universe: Extraordinary Discoveries Through Ordinary Eyes
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Overview
Product Details
| ISBN-13: | 9781789042030 |
|---|---|
| Publisher: | Hunt, John Publishing |
| Publication date: | 11/29/2019 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 177 |
| File size: | 733 KB |
About the Author
Richard Dieter is a graduate of Georgetown University Law Center, and he has contributed to several books on Law and history in the United States. His published reports have been widely cited by the national media and government leaders. Dieter served as Executive Director of a national non-profit organisation whose website was selected for archival research by the Library of Congress. His most recent report concerning military veterans received the Congressional Black Caucus’s Veterans Braintrust Award. Dieter lives in Silver Spring, Maryland.
Read an Excerpt
CHAPTER 1
Exploring the Universe on Its Grandest Scale
At every step, the expansion of our universe was at the same time an expansion of the human horizons of knowledge.
– Mario Livio
Humans have always gazed up into the night sky and wondered: what else is out there? The daytime is our comfort zone with just one star — our sun — reliably warming us and sustaining life. But at night, the stars are aloof, twinkling against a black sky, withholding their mysteries. Could there be other places in the universe, maybe other green and blue planets where life is also thriving, perhaps looking back down at us?
What do we know about this immense universe that reveals itself only grudgingly? The stars barely change their orientation from night to night and stay fixed with respect to each other. The big dipper roams the sky as the Earth turns, but it is always a dipper. The stars reveal almost nothing of themselves. Even with a telescope, they may only appear as bright dots.
If you watch the sky carefully, you can't help but notice that some points of light have an independent streak. They change their position more dramatically than the other lights, moving right through the constellations instead of staying with one. These are the planets of our solar system.
The Gifts of Jupiter
In a backyard telescope, it's possible to explore a few of these planets more closely. My favorite one is Jupiter. It's very bright and easy to see, although it just looks like a bright star to the naked eye. But with a telescope, a whole new world appears. Jupiter has color, bands of yellow and brown. The bands encircle the planet and appear tilted at an angle relative to our perspective. It's not hard to picture that the planet is revolving around its axis and coursing through space as the night passes.
Something else pops into view with a telescope centered on Jupiter. There are four small lights close to the planet. Depending on when you look, you might only see two or three, but eventually all four will appear. Sometimes they seem to be in a straight line. Clearly, they are associated with the planet because they follow it through the sky. They are four of the many (79 in all) moons of Jupiter, constantly orbiting the planet just as our moon orbits the Earth. Sometimes one passes in front of the planet (relative to our line of sight), and you can see its shadow as a dark dot on the planet's surface. At other times the moons pass behind the planet, decreasing the number of moons you can see.
Jupiter is a stunning example that our universe may be full of other worlds, different from the Earth, but not like the fiery and distant stars. Jupiter has contributed to important scientific discoveries that have changed our understanding of the universe. In the 17th century, Galileo Galilei was one of the first persons to explore the sky with a telescope. He was able to see the same moons of Jupiter that an amateur astronomer can easily see today. He realized that if those four moons were orbiting Jupiter, then they are not simply part of a dome of lights that encircles the Earth and moves across the night sky, as was originally thought. The moons of Jupiter were one piece of evidence that the Earth may not be the center of the universe. Gradually, it became clear that the Earth and all of our neighboring planets orbit the sun, ending the assumptions about the Earth having an exceptional position in the sky.
Jupiter and its moons led to another critical breakthrough — measuring the speed of light. Light is essential to everything humans do. Although it is impossible for our senses to detect the movement of light, there were reasons to believe that it did not appear instantaneously, but moved through space like sound travels through the air, though much more quickly.
The reason we are able to see Jupiter and its moons is that the light of the sun illuminates them and that light is reflected back towards Earth. (That is not true of the stars, which are their own source of light.) The distance that light has to travel in reaching the Earth from Jupiter varies depending on whether it is relatively nearer or further from us. Think of two runners on an oval track running at different speeds. At first, the faster runner will pull away from the slower one, but eventually she will lap the slower runner and the two will be close again. Jupiter takes 12 Earth-years to complete a trip around the sun, while the Earth, of course, does it in one year.
The moons of Jupiter orbit it in a regular fashion, so once a moon, say Io, disappears behind Jupiter in its orbit, its reappearance will occur at a predictable time. But if Jupiter and its moons are at a period when they are farther away from Earth, the light from the emerging moon will take longer to reach the Earth than if this was all happening at a time when Jupiter was closer to Earth. If we know the difference in time it takes for Io to reappear and the difference in distance between the far and close observing times of Jupiter, we can approximately calculate the speed of light. Speed is simply distance divided by time.
Using this idea, the first credible measurement of the speed of light was made by Ole Rømer in 1676. His data led to a calculation of 131,000 miles per second, at least in the ballpark of the actual figure of 186,300 miles per second.
(I recently read of an even simpler experiment involving only Velveeta cheese and a microwave oven that could also be used to calculate the speed of light. Unfortunately, no one in the 1600s had a microwave oven, or Velveeta cheese. They also didn't know that light traveled in waves, which is critical to this very rough calculation.)
The speed of light turns out to be one of the most important numbers describing the world we live in. It's a universal speed limit and is surprisingly independent of whether light comes from an object moving towards you or away. More on that later. (By the way, Saturn with its rings and moons is also an amazing sight through a backyard telescope.)
Probes and a few rovers have explored all of the planets in our solar system, and these places seem unlikely to sustain life like ours. In the near future, we will probably know if our neighbor Mars has supported microscopic life, perhaps frozen in its underground ice. More promisingly, there may be existing life in the oceans of one of the moons of Jupiter or Saturn. There is much to explore.
The Life of Stars
The more distant stars gradually revealed their secrets to astronomers as larger telescopes were developed. How far away are the stars? Do they orbit around anything else? What are they made of? How many are there? If they are very far away, but still glow with an evident brightness, perhaps they are hot furnaces like our sun. We cannot feel their warmth, but some source of energy is sending their light across the universe in a constant glow.
We now believe that the distant stars and our sun are indeed similar. There are thousands of stars visible to the naked eye, with a concentrated band of them glowing across the sky in what is called the Milky Way. And if stars are like our sun, perhaps they, too, have planets orbiting them, thereby offering a vast number of the potential places where life could exist in the universe. Although planets around other suns have not been seen directly, there is strong evidence that solar systems like ours are quite common.
The closest other sun (star) to us is Proxima Centauri. Its light takes 4.24 years to reach us, traveling a distance of about 25 trillion miles. By comparison, our own sun is "only" about 93 million miles away from the Earth. Distances in space quickly become too cumbersome to express in miles, so astronomers came up with a more manageable metric, and then gave it a confusing name: light-years. It sounds like an amount of time, but actually is the distance that light travels in an Earth year. It is equivalent to approximately 5.9 trillion miles, with light traveling at 670 million miles per hour. (Scientifically speaking, these distances should be expressed in meters.) Proxima Centauri, therefore, is 4.24 light-years away from us (25 trillion miles away ÷ 5.9 trillion miles per light-year). If a giant flare erupted there, we wouldn't see it for over 4 years. A similar flare on our own sun wouldn't be visible to us for about 9 minutes.
The rest of the stars are further away, some much, much further. On a clear night, away from the city, you might be able to observe some fuzzy white puffs in the sky, less defined than the point-like stars. Originally, these were called nebula because they resembled a gaseous collection of light. More powerful telescopes detected that some of those fuzzy clouds were actually conglomerations of stars. Suddenly the universe became immensely larger.
Large collections of stars bound together by gravity are called galaxies. All the distinct stars our unaided eyes can see by gazing upward are part of our Milky Way Galaxy, which would also appear as a fuzzy blob if seen from very far away. The discovery in the early 20th century that other galaxies existed opened up vast possibilities for the existence of other life in the universe. Each galaxy contains billions of stars, and each star could be surrounded by a set of planets. Just as the Earth is not the center of our solar system, our solar system is not the center of our galaxy, and our galaxy is just one of hundreds of billions of galaxies in the universe.
Typical galaxies contain at least 100 billion stars, with larger ones encompassing a trillion stars. There are approximately 200 billion such galaxies in our known universe. Hence, our sun is just one of about 20,000,000,000,000,000,000,000 other stars. At times it feels like we barely matter. It's hard to imagine that the vast universe cares about whether we are happy or sad. This is certainly the sentiment of the universe's bureaucracy in The Hitchhiker's Guide to the Galaxy by Douglas Adams, where the Earth (and all its inhabitants) is scheduled for demolition because it stands in the way of a proposed interstellar highway in space. We're just a boulder along a future road that needs to be cleared away.
On the other hand, the universe constantly connects with us in subtle ways. When two black holes over a billion light-years away collide, they send out a signal, a ripple in the fabric of spacetime, that we humans can detect. (See Chapter 2.) We may not be the center of this vast world, but that is partly because the universe has no center. It is all interconnected.
Big, and Getting Much Bigger
If the number of stars weren't daunting enough, it appears that our whole visible universe is expanding. Careful measurements of the most distant galaxies reveal that they are retreating from us, and the further ones are retreating faster than the closer ones. Since the stars and the galaxies are so far away and there is no reference point to measure how far they have traveled, it's difficult to determine their speed. Light travels in waves, and if the source of the light is receding from us, the waves reach us in a more stretched-out form. The same thing happens to sound waves, which is why an ambulance siren moving away from you has a different pitch than when it is approaching you. Astronomers have been able to measure the relative stretching of light waves and have thus arrived at the speed at which stars and galaxies are receding.
Are the stars and galaxies spreading out into the infinite emptiness of space? Not exactly. It is space that is actually expanding, though that is a hard notion to get one's head around. Scientists don't really know what space is. They are adamant that it's not empty nothingness. It might be lumpy at the finest-grained level, or it might be continuous. It contains fields of energy and virtual particles popping into and out of existence. We will explore the really small aspects of the universe in the second section of this book. Suffice for now to say that the container of all our stuff is growing from the inside out. It's not just stars at the furthest limits that are moving away from us, it's every bit of space from our solar system to the space between the farthest galaxies. It is growing like a rising muffin in the oven, expanding from the inside.
Why haven't we noticed this before? One reason is that there are counter forces that keep the world closest to us looking like itself, even as distant galaxies are receding from ours at vast speeds. On a molecular level, forces within atoms keep us together so that our waistlines (and heads) don't grow with the expanding universe. In every atom, protons attract electrons, and even forces within the nucleus of an atom bind its particles together.
The Earth is partly held together by gravity, as is our solar system and our Milky Way Galaxy. Even clusters of galaxies are bound by the mutual attraction of their members. That muffin of space in the oven is really a giant blueberry muffin, just starting to bake. It is rising all around us, but the blueberries remain intact, even as they drift further apart from one another.
More recently, another surprising discovery was made. The universe is not just expanding, the rate of expansion is increasing. It's like something just supercharged the oven, and instead of the muffins gently rising, they're suddenly starting to explode.
Isaac Newton proposed fundamental principles (laws) about the movement of objects that are still useful guidelines today. One such law was that an object in motion will stay in motion unless acted on by an outside force. Neglecting gravity and friction, if you throw a ball (say, in outer space) it will continue moving in a straight line at a constant speed. If our universe started with the force of a big bang, it would not be surprising that space is continuing to expand today.
But also according to Newton, for an object to accelerate (that is, to increase its speed) an additional force would be needed. If the universe is not only expanding, but is expanding at ever increasing speeds, then there should be a force that is causing that acceleration. Given the size of the universe, that is one heck of a force. Scientists do not know what the force is that is speeding up the expansion and have simply labeled it "dark energy." Gravity also acts through the entire universe, but it has an attractive effect. Dark energy is a repulsive force, apparently much stronger than gravity.
Not understanding this force is a pretty big deal. At one point, physicists thought that the era of scientific discovery was over, and all that remained was fine-tuning the calculations in the laws of the universe. Now we've discovered the presence of a powerful force permeating the entire universe, and we don't know what it is. Equally mysterious is that scientists have discovered that there is a large amount of matter in the universe that we had not accounted for. It's appropriately called "dark matter." It apparently is providing some of the gravity that holds galaxies together. Combined, dark matter and dark energy comprise about 95% of the essential stuff of the universe. Everything else that we can see or measure is just a small smattering of what's out there. There's a future in science after all.
Despite Einstein's speed limits for travel, space is allowed to expand at a rate even faster than the speed of light. Einstein concluded — and no one has disproved — that anything with mass must travel at less than the speed of light through space. But space itself is not traveling; it's expanding, growing from within. The net result is that some objects in space have moved further from some other objects in a time that would compute to a speed greater than the speed of light. It's like an earthquake opening a rift between two mountains: the mountains themselves aren't traveling, but the distance between them has grown.
This expansion has profound implications for our future, though nothing to immediately worry about. If the groups of stars and galaxies are moving away from us at speeds faster than light, we will never see them again. Their light will never reach us. The distance between them and us is growing faster than even light can keep up with. Billions and billions of years from now, there won't be much to look at. And even those few lights we can see will flicker out into a cold ash. Unless, of course, the whole shebang (as Timothy Ferris calls it) suddenly stops expanding and starts contracting. Stranger things have happened.
(Continues…)
Excerpted from "Reflections on a Surprising Universe"
by .
Copyright © 2018 Richard Dieter.
Excerpted by permission of John Hunt Publishing Ltd..
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Table of Contents
Preface, 1,
Part I: Looking for Our Place in the Stars, 3,
Introduction, 5,
Chapter 1: Exploring the Universe on Its Grandest Scale, 11,
A Cosmos of Constant Change,
Chapter 2: Much More Than Stars, 25,
Black Holes, Bending Space, Gravitational Waves,
Chapter 3: One Universe or Many?, 39,
A Multiplicity of Multiverses,
Chapter 4: Life on Other Planets, 50,
Reaching Out to E.T.,
Chapter 5: Time and Space, 62,
Even Simple Things Can Be Hard to Understand,
Chapter 6: Why Is There Something Instead of Nothing?, 77,
And How Much of Something Are We?,
Part II: From Telescope to Microscope, 83,
Chapter 7: A Code for Being Human, 85,
DNA, Selfish Genes, and Machines,
Chapter 8: Our Common Ground with the Universe, 102,
Take Three Particles and What Do You Get?,
Chapter 9: Stranger Still, 115,
The World At Its Most Fundamental Is Not What Anyone Expected,
Chapter 10: On The Horizon, 129,
Quantum Computers, A Theory of Strings,
Notes, 139,
Bibliography, 151,