Death by Black Hole: And Other Cosmic Quandaries (3 page)

A
mong our five senses, sight is the most special to us. Our eyes allow us to register information not only from across the room but also from across the universe. Without vision, the science of astronomy would never have been born and our capacity to measure our place in the universe would have been hopelessly stunted. Think of bats. Whatever bat secrets get passed from one generation to the next, you can bet that none of them is based on the appearance of the night sky.

When thought of as an ensemble of experimental tools, our senses enjoy an astonishing acuity and range of sensitivity. Our ears can register the thunderous launch of the space shuttle, yet they can also hear a mosquito buzzing a foot away from our head. Our sense of touch allows us to feel the magnitude of a bowling ball dropped on our big toe, just as we can tell when a one-milligram bug crawls along our arm. Some people enjoy munching on habanero peppers while sensitive tongues can identify the presence of food flavors on the level of parts per million. And our eyes can register the bright sandy terrain on a sunny beach, yet these same eyes have no trouble spotting a lone match, freshly lit, hundreds of feet across a darkened auditorium.

But before we get carried away in praise of ourselves, note that what we gain in breadth we lose in precision: we register the world’s stimuli in logarithmic rather than linear increments. For example, if you increase the energy of a sound’s volume by a factor of 10, your ears will judge this change to be rather small. Increase it by a factor of 2 and you will barely take notice. The same holds for our capacity to measure light. If you have ever viewed a total solar eclipse you may have noticed that the Sun’s disk must be at least 90 percent covered by the Moon before anybody comments that the sky has darkened. The stellar magnitude scale of brightness, the well-known acoustic decibel scale, and the seismic scale for earthquake severity are each logarithmic, in part because of our biological propensity to see, hear, and feel the world that way.

WHAT, IF ANYTHING
, lies beyond our senses? Does there exist a way of knowing that transcends our biological interfaces with the environment?

Consider that the human machine, while good at decoding the basics of our immediate environment—like when it’s day or night or when a creature is about to eat us—has very little talent for decoding how the rest of nature works without the tools of science. If we want to know what’s out there then we require detectors other than the ones we are born with. In nearly every case, the job of a scientific apparatus is to transcend the breadth and depth of our senses.

Some people boast of having a sixth sense, where they profess to know or see things that others cannot. Fortune-tellers, mind readers, and mystics are at the top of the list of those who lay claim to mysterious powers. In so doing, they instill widespread fascination in others, especially book publishers and television producers. The questionable field of parapsychology is founded on the expectation that at least some people actually harbor such talents. To me, the biggest mystery of them all is why so many fortune-telling psychics choose to work the phones on TV hotlines instead of becoming insanely wealthy trading futures contracts on Wall Street. And here’s a news headline none of us has seen, “Psychic Wins the Lottery.”

Quite independent of this mystery, the persistent failures of controlled, double-blind experiments to support the claims of parapsychology suggest that what’s going on is nonsense rather than sixth sense.

On the other hand, modern science wields dozens of senses. And scientists do not claim these to be the expression of special powers, just special hardware. In the end, of course, the hardware converts the information gleaned from these extra senses into simple tables, charts, diagrams, or images that our inborn senses can interpret. In the original
Star Trek
sci-fi series, the crew that beamed down from their starship to the uncharted planet always brought with them a tricorder—a handheld device that could analyze anything they encountered, living or inanimate, for its basic properties. As the tricorder was waved over the object in question, it made an audible spacey sound that was interpreted by the user.

Suppose a glowing blob of some unknown substance were parked right in front of us. Without some diagnostic tool like a tricorder to help, we would be clueless to the blob’s chemical or nuclear composition. Nor could we know whether it has an electromagnetic field, or whether it emits strongly in gamma rays, x-rays, ultraviolet, microwaves, or radio waves. Nor could we determine the blob’s cellular or crystalline structure. If the blob were far out in space, appearing as an unresolved point of light in the sky, our five senses would offer us no insight to its distance, velocity through space, or its rate of rotation. We further would have no capacity to see the spectrum of colors that compose its emitted light, nor could we know whether the light is polarized.

Without hardware to help our analysis, and without a particular urge to lick the stuff, all we can report back to the starship is, “Captain, it’s a blob.” Apologies to Edwin P. Hubble, the quote that opens this chapter, while poignant and poetic, should have instead been:

Equipped with our five senses, along with telescopes and microscopes and mass spectrometers and seismographs and magnetometers and particle accelerators and detectors across the electromagnetic spectrum, we explore the universe around us and call the adventure science.

 

Think of how much richer the world would appear to us and how much earlier the nature of the universe would have been discovered if we were born with high-precision, tunable eyeballs. Dial up the radio-wave part of the spectrum and the daytime sky becomes as dark as night. Dotting that sky would be bright and famous sources of radio waves, such as the center of the Milky Way, located behind some of the principal stars of the constellation Sagittarius. Tune into microwaves and the entire cosmos glows with a remnant from the early universe, a wall of light set forth 380,000 years after the big bang. Tune into x-rays and you immediately spot the locations of black holes, with matter spiraling into them. Tune into gamma rays and see titanic explosions scattered throughout the universe at a rate of about one per day. Watch the effect of the explosion on the surrounding material as it heats up and glows in other bands of light.

If we were born with magnetic detectors, the compass would never have been invented because we wouldn’t ever need one. Just tune into Earth’s magnetic field lines and the direction of magnetic north looms like Oz beyond the horizon. If we had spectrum analyzers within our retinas, we would not have to wonder what we were breathing. We could just look at the register and know whether the air contained sufficient oxygen to sustain human life. And we would have learned thousands of years ago that the stars and nebulae in the Milky Way galaxy contain the same chemical elements found here on Earth.

And if we were born with big eyes and built-in Doppler motion detectors, we would have seen immediately, even as grunting troglodytes, that the entire universe is expanding—with distant galaxies all receding from us.

If our eyes had the resolution of high-performance microscopes, nobody would have ever blamed the plague and other sicknesses on divine wrath. The bacteria and viruses that made us sick would be in plain view as they crawled on our food or as they slid through open wounds in our skin. With simple experiments, we could easily tell which of these bugs were bad and which were good. And of course postoperative infection problems would have been identified and solved hundreds of years earlier.

If we could detect high-energy particles, we would spot radioactive substances from great distances. No Geiger counters necessary. We could even watch radon gas seep through the basement floor of our homes and not have to pay somebody to tell us about it.

THE HONING OF
our senses from birth through childhood allows us, as adults, to pass judgment on events and phenomena in our lives, declaring whether they “make sense.” Problem is, hardly any scientific discoveries of the past century flowed from the direct application of our five senses. They flowed instead from the direct application of sense-transcendent mathematics and hardware. This simple fact is entirely responsible for why, to the average person, relativity, particle physics, and 10-dimensional string theory make no sense. Include in the list black holes, wormholes, and the big bang. Actually, these ideas don’t make much sense to scientists either, or at least not until we have explored the universe for a long time, with all the senses that are technologically available. What emerges, eventually, is a newer and higher level of “common sense” that enables a scientist to think creatively and to pass judgment in the unfamiliar underworld of the atom or in the mind-bending domain of higher-dimensional space. The twentieth-century German physicist Max Planck made a similar observation about the discovery of quantum mechanics:

Modern Physics impresses us particularly with the truth of the old doctrine which teaches that there are realities existing apart from our sense-perceptions, and that there are problems and conflicts where these realities are of greater value for us than the richest treasures of the world of experience.
(1931, p. 107)

 

Our five senses even interfere with sensible answers to stupid metaphysical questions like, “If a tree falls in the forest and nobody is around to hear it, does it make a sound?” My best answer is, “How do you know it fell?” But that just gets people angry. So I offer a senseless analogy, “Q: If you can’t smell the carbon monoxide, then how do you know it’s there? A: You drop dead.” In modern times, if the sole measure of what’s out there flows from your five senses then a precarious life awaits you.

Discovering new ways of knowing has always heralded new windows on the universe that tap into our growing list of nonbiological senses. Whenever this happens, a new level of majesty and complexity in the universe reveals itself to us, as though we were technologically evolving into supersentient beings, always coming to our senses.

U
ntil Isaac Newton wrote down the universal law of gravitation, there was little reason to presume that the laws of physics on Earth were the same as everywhere else in the universe. Earth had earthly things going on and the heavens had heavenly things going on. Indeed, according to many scholars of the day, the heavens were unknowable to our feeble, mortal minds. As further detailed in Section 7, when Newton breached this philosophical barrier by rendering all motion comprehensible and predictable, some theologians criticized him for leaving nothing for the Creator to do. Newton had figured out that the force of gravity pulling ripe apples from their branches also guides tossed objects along their curved trajectories and directs the Moon in its orbit around Earth. Newton’s law of gravity also guides planets, asteroids, and comets in their orbits around the Sun and keeps hundreds of billions of stars in orbit within our Milky Way galaxy.

This universality of physical laws drives scientific discovery like nothing else. And gravity was just the beginning. Imagine the excitement among nineteenth-century astronomers when laboratory prisms, which break light beams into a spectrum of colors, were first turned to the Sun. Spectra are not only beautiful but also contain oodles of information about the light-emitting object, including its temperature and composition. Chemical elements reveal themselves by their unique patterns of light or dark bands that cut across the spectrum. To people’s delight and amazement, the chemical signatures on the Sun were identical to those in the laboratory. No longer the exclusive tool of chemists, the prism showed that as different as the Sun is from Earth in size, mass, temperature, location, and appearance, both contained the same stuff—hydrogen, carbon, oxygen, nitrogen, calcium, iron, and so forth. But more important than a laundry list of shared ingredients was the recognition that whatever laws of physics prescribed the formation of these spectral signatures on the Sun, the same laws were operating on Earth, 93 million miles away.

So fertile was this concept of universality that it was successfully applied in reverse. Further analysis of the Sun’s spectrum revealed the signature of an element that had no known counterpart on Earth. Being of the Sun, the new substance was given a name derived from the Greek word
helios
(the Sun). Only later was it discovered in the lab. Thus, “helium” became the first and only element in the chemist’s periodic table to be discovered someplace other than Earth.

OKAY, THE LAWS
of physics work in the solar system, but do they work across the galaxy? Across the universe? Across time itself? Step by step, the laws were tested. The nearby stars also revealed familiar chemicals. Distant binary stars, bound in mutual orbit, seem to know all about Newton’s laws of gravity. For the same reason, so do binary galaxies.

And, like the geologist’s stratified sediments, the farther away we look, the further back in time we see. Spectra from the most distant objects in the universe show the same chemical signatures that we see everywhere else in the universe. True, heavy elements were less abundant back then—they are manufactured primarily in subsequent generations of exploding stars—but the laws describing the atomic and molecular process that created these spectral signatures remain intact.

Of course, not all things and phenomena in the cosmos have counterparts on Earth. You’ve probably never walked through a cloud of glowing million-degree plasma, and you’ve probably never stumbled upon a black hole on the street. What matters is the universality of the laws of physics that describe them. When spectral analysis was first turned to the light emitted by interstellar nebulae, an element appeared that, once again, had no counterpart on Earth. But the periodic table of elements had no missing boxes; when helium was discovered there were several. So astrophysicists invented the name “nebulium” as a placeholder, until they could figure out what was going on. Turned out that in space, gaseous nebulae are so rarefied that atoms go long stretches without colliding with each other. Under these conditions, electrons can do things within atoms that had never before been seen in Earth labs. Nebulium was simply the signature of ordinary oxygen doing extraordinary things.

This universality of physical laws tells us that if we land on another planet with a thriving alien civilization, they will be running on the same laws that we have discovered and tested here on Earth—even if the aliens harbor different social and political beliefs. Furthermore, if you wanted to talk to the aliens, you can bet they don’t speak English or French or even Mandarin Chinese. You don’t even know whether shaking their hands—if indeed they have hands to shake—would be considered an act of war or of peace. Your best hope is to find a way to communicate using the language of science.

Such an attempt was made in the 1970s with the
Pioneer 10
and
11
and
Voyager 1
and
2
spacecraft, the only ones given a great enough speed to escape the solar system’s gravitational pull.
Pioneer
donned a golden etched plaque that showed, in pictograms, the layout of our solar system, our location in the Milky Way galaxy, and the structure of the hydrogen atom.
Voyager
went further and included diverse sounds from mother Earth including the human heartbeat, whale “songs,” and musical selections ranging from the works of Beethoven to Chuck Berry. While this humanized the message, it’s not clear whether alien ears would have a clue what they were listening to—assuming they have ears in the first place. My favorite parody of this gesture was a skit on
Saturday Night Live
, appearing shortly after the
Voyager
launch. NASA receives a reply from the aliens who recovered the spacecraft. The note simply requests, “Send more Chuck Berry.”

AS WE WILL
see in great detail in Section 3, science thrives not only on the universality of physical laws but also on the existence and persistence of physical constants. The constant of gravitation, known by most scientists as “big G,” supplies Newton’s equation of gravity with the measure of how strong the force will be, and has been implicitly tested for variation over eons. If you do the math, you can determine that a star’s luminosity is steeply dependent on big G. In other words, if big G had been even slightly different in the past, then the energy output of the Sun would have been far more variable than anything that the biological, climatological, or geological records indicate. In fact, no time-dependent or location-dependent fundamental constants are known—they appear to be truly constant.

Such are the ways of our universe.

Among all constants, the speed of light is surely the most famous. No matter how fast you go, you will never overtake a beam of light. Why not? No experiment ever conducted has ever revealed an object of any form reaching the speed of light. Well-tested laws of physics predict and account for this. These statements sound closed-minded. True, some of the most embarrassing science-based proclamations in the past have underestimated the ingenuity of inventors and engineers: “We will never fly.” “Flying will never be commercially feasible.” “We will never fly faster than sound.” “We will never split the atom.” “We will never go to the Moon.” You’ve heard them. What they have in common is that no established law of physics stood in their way.

The claim “We will never outrun a beam of light” is a qualitatively different prediction. It flows from basic, time-tested physical principles. No doubt about it. Highway signs for interstellar travelers of the future will surely read:

The good thing about the laws of physics is that they require no law enforcement agencies to maintain them, although I once owned a nerdy T-shirt that loudly proclaimed, “OBEY GRAVITY.”

Many natural phenomena reflect the interplay of multiple physical laws operating at once. This fact often complicates the analysis and, in most cases, requires supercomputers to calculate things and to keep track of important parameters. When comet Shoemaker-Levy 9 plunged into and then exploded within Jupiter’s gas-rich atmosphere in 1994, the most accurate computer model of what was to happen combined the laws of fluid mechanics, thermodynamics, kinematics, and gravitation. Climate and weather represent other leading examples of complicated (and difficult-to-predict) phenomena. But the basic laws governing them are still at work. Jupiter’s Great Red Spot, a raging anticyclone that has been going strong for at least 350 years, is driven by the identical physical processes that generate storms on Earth and elsewhere in the solar system.

THE CONSERVATION LAWS
, where the amount of some measured quantity remains unchanged
no matter what
are another class of universal truths. The three most important are the conservation of mass and energy, the conservation of linear and angular momentum, and the conservation of electric charge. These laws are in evidence on Earth and everywhere we have thought to look in the universe—from the domain of particle physics to the large-scale structure of the universe.

In spite of all this boasting, all is not perfect in paradise. As already noted, we cannot see, touch, or taste the source of 85 percent of the gravity of the universe. This mysterious dark matter, which remains undetected except for its gravitational pull on matter we see, may be composed of exotic particles that we have yet to discover or identify. A tiny subset of astrophysicists, however, remain unconvinced and have suggested that dark matter does not exist—you simply need to modify Newton’s law of gravity. Just add a few components to the equations and all will be well.

Perhaps one day we will learn that Newton’s gravity indeed requires adjustment. That’ll be okay. It has happened once before. In 1916, Albert Einstein published his general theory of relativity, which reformulated the principles of gravity in a way that applied to objects of extremely high mass, a realm unknown to Newton, and where his law of gravity breaks down. The lesson? Our confidence flows through the range of conditions over which a law has been tested and verified. The broader this range, the more powerful the law becomes in describing the cosmos. For ordinary household gravity, Newton’s law works just fine. For black holes and the large-scale structure of the universe, we need general relativity. They each work flawlessly in their own domain, wherever that domain may be in the universe.

TO THE SCIENTIST
, the universality of physical laws makes the cosmos a marvelously simple place. By comparison, human nature—the psychologist’s domain—is infinitely more daunting. In America, school boards vote on the subjects to be taught in the classroom, and in some cases these votes are cast according to the whims of social and political tides or religious philosophies. Around the world, varying belief systems lead to political differences that are not always resolved peacefully. And some people talk to bus stop stanchions. The remarkable feature of physical laws is that they apply everywhere, whether or not you choose to believe in them. After the laws of physics, everything else is opinion.

Not that scientists don’t argue. We do. A lot. When we do, however, we are usually expressing opinions about the interpretation of ratty data on the frontier of our knowledge. Wherever and whenever a physical law can be invoked in the discussion, the debate is guaranteed to be brief: No, your idea for a perpetual motion machine will never work—it violates laws of thermodynamics. No, you can’t build a time machine that will enable you to go back and kill your mother before you were born—it violates causality laws. And without violating momentum laws, you cannot spontaneously levitate and hover above the ground, whether or not you are seated in the lotus position. Although, in principle, you could perform this stunt if you managed to let loose a powerful and sustained exhaust of flatulence.

Knowledge of physical laws can, in some cases, give you the confidence to confront surly people. A few years ago I was having a hot-cocoa nightcap at a dessert shop in Pasadena, California. I had ordered it with whipped cream, of course. When it arrived at the table, I saw no trace of the stuff. After I told the waiter that my cocoa was plain, he asserted I couldn’t see the whipped cream because it sank to the bottom. Since whipped cream has a very low density and floats on all liquids that humans consume, I offered the waiter two possible explanations: either somebody forgot to add the whipped cream to my hot cocoa or the universal laws of physics were different in his restaurant. Unconvinced, he brought over a dollop of whipped cream to test for himself. After bobbing once or twice in my cup, the whipped cream sat up straight and afloat.

What better proof do you need of the universality of physical law?