Letters from an Astrophysicist

by Neil deGrasse Tyson

Now that people communicate with one another primarily by social media, letter-writing has become a lost art. The greatest casualty may be our growing inability to find words that precisely communicate our feelings and emotions. Why else the need for that burgeoning catalog of emoticons to supplement our written correspondence? A smiley face. A snarky face. A heart. A thumbs-up. But when the world stimulates your curiosity; when your state of not knowing leaves you restless; when your existential angst overflows; sometimes you just have to write a full-up letter to somebody.

But there is another kind of hope—it’s the challenge of learning about the real world and using our intelligence to change things for the better. In this way, it’s the individual who is empowered to bring hope to the world.

IQ correlates nicely with GPA in high school and college, but after your first job, nobody ever asks what your college GPA was. What matters are your people skills, leadership skills, real-world problem solving skills, integrity, business acumen, reliability, ambition, work ethic, kindness, compassion, etc. So for me, conversations about race and IQ are of no practical consequence, any more than are conversations about race and hair color, or race and food preferences.

One objective reality is that our government doesn’t work, not because we have dysfunctional politicians, but because we have dysfunctional voters. As a scientist and educator, my goal, then, is not to become President and lead a dysfunctional electorate, but to enlighten the electorate so they might choose the right leaders in the first place.

But it comes with a recurring risk: knowing enough about a subject to think you are right, but not enough about the subject to know you are wrong.

Note that eyewitness testimony is, by far, the weakest form of evidence that a person can present in support of a claim. In spite of its high value in the court of law, in the “court” of science, eyewitness testimony is essentially useless. Psychologists have known for quite some time how ineffective the human senses are as data taking devices. Note that the pedigree of the observer is irrelevant here—as long as he or she is human, the fallibility of observation is manifest.

Note further that claims of a “cover-up” or “conspiracy” is the battle cry of people who want to believe, in the face of insufficient data to fully support their claims.

It’s the end of what Mayan scholars call the “long count,” begun on August 11, 3113 BC, the beginning of the universe according to Mayan calculations. At the end of the long count, they imagined the end of the universe. With regard to the beginning of the universe, they were off by at least 13 billion years. So there’s no reason to think they will get the end correct.

If you feel confident that there are eight-foot, undocumented, prehistoric apes running around the Pacific Northwest, you should mount expeditions to find them—you don’t have to kill it; just capture one. Your efforts will be better spent in search of useful evidence than in trying to convince people of what you think is true in the absence of it.

How about the fact that the entire universe is composed of just 92 elements?

For me, however, I have an unorthodox philosophy regarding root-finding. I just don’t care. And that’s not a passive absence of caring it’s an active absence of caring. Since any two people in the world have a common ancestor—depending on how far back you look, the line we draw to establish family lineage is entirely arbitrary. When I wonder what I am capable of as a human being, I don’t look to “relatives,” I look to all human beings. That is the genetic relationship that matters to me. The genius of Isaac Newton, the courage of Joan of Arc and Gandhi, the athletic feats of Michael Jordan, the oratorical skills of Sir Winston Churchill, the compassion of Mother Teresa. I look to the entire human race for inspiration for what I can be—because I am human. I don’t care if I am a descendent of kings or paupers, saints or sinners, the brave or cowardly. My life is what I make of it.

Furthermore, as an atheist, you surely use the words: “holiday” and “goodbye,” yet their origins come from “holy day,” and “god be with you.” As in anything in life, you must choose your battles. So may I recommend that you adopt CE and BCE and leave it at that? Instead, devote your energies to the real battlefield—the “sanctity” of the science classroom in the face of religious fundamentalists who perennially attempt to influence the science curriculum with religious-based philosophies.

The most enduring thing about being human is the discovery of cosmic truths that transcend culture, politics, religion, and time, forming the corpus of knowledge and wisdom that we call civilization.

On a more philosophical level . . . Gone is your knowledge of our place in the universe—the only human pursuit that has transcended culture, region, and time. All supplied by the Hubble Space Telescope, the Martian rovers, and the countless other spacecraft, with and without humans, that have left Earth to explore. Others who do support space exploration would have access to these things. But not you. All because you would not annually check a box that allocated 6/10 of a penny of your tax dollar. That is the entire allocation to NASA. That is the cost of your access to the universe that you so willingly decline. How much is the universe worth to you?

For example, nowhere in the Bible is Earth described as a three-dimensional object. All references to it are flat. And until the 15th century, so too were all maps of the world, informed by scriptures. We can celebrate the cultural history of this notion, but it’s objectively false. Same holds for the value of Pi. In the Bible, a passage (I Kings VII) can only be true if Pi exactly equals 3.0. But we know better than this (so too did the earlier Babylonians, who calculated that Pi was a number between 3 and 4). But just because the Bible says Pi = 3, does not mean Pi = 3. The statement is objectively wrong, and is therefore not a matter of opinion. The fact that the people who wrote the Bible made Pi = 3 and Earth a flat disc is of some historical interest and worthy of study in history class, philosophy class, or religion class. But it has no place in the field of science, whose goal is to find truths of the universe that sit independently of opinion.

You declare that neither of us can prove our religious beliefs. But I can (and do) know the shape of the Earth, Moon, stars, and universe, the origin of the chemical elements, the age of the Earth and the universe, the extinction episodes of the fossil record, the impact of asteroids on Earth, the genetic commonality among all life on Earth, the genetic proximity of chimpanzees and humans, and countless other objective truths about the world. So your assertion is false and shows a lack of education about the process of science and the nature of discovery. When this happens, it’s usually not the person’s fault, and is traceable to educators in your life who did not spend enough time training you how to think, as distinct from what to think.

Scientists are all human, complete with human frailties and biases and susceptibilities. That’s why trends in the data remain the primary commodity of what is true in science, and not the impassioned testimonies of scientists themselves.

The theory of evolution is not something to “believe in.” Science follows evidence. And when strong evidence supports an idea, the concept of belief, when invoked the way religious people use the word, is unnecessary. In other words, established science is not an ensemble of beliefs, it’s a system of ideas supported by verifiable evidence.

Evidence for God In a long exchange from 2008, Andrew McLemore expressed his enthusiasm for science as a tool to peer into God’s cosmic handiwork. But he wondered what level evidence might convince a skeptic that there’s a better-than-even chance that God exists. Dear Andrew, I think often about what would constitute evidence for God. How about if, after adjusting for income and access to health care, pious people all lived longer than non-pious people? How about when a plane crashes, only the pious people survive? How about Jesus comes when people say he will come? (His second coming has been predicted by Christians for hundreds of occasions that have already passed, spanning the last 2000 years.) How about people pray for peace, and then all wars in the world stop permanently? How about good things happen exclusively to good people and bad things happen exclusively to bad people? How about an earthquake strikes Portugal on All Saints Day, while everyone is in Church, as it did in 1755, and it kills only people who are not in Church, rather than the tens of thousands of people who were, as what actually happened that fateful morning. These events would trigger serious (scientific) conversation about the existence of God and how he treats people who worship him versus those who do not. Sincerely, Neil deGrasse Tyson

This distinction between “how” and “why,” while resonant with emergent philosophies, is not entirely clean. The following are just a few (pure) “why” questions for which faith-based inquiry is powerless to answer, beyond the catch-all response of “Because God made it that way”: •Why is the sky blue? •Why does the moon always show the same face to Earth? •Why does Venus go through phases like the Moon? •Why does the Sun have spots? •Why do hurricanes in the northern hemisphere rotate counterclockwise? •Why is August hotter than June, when the Sun’s rays on Earth are more direct in June?

Active scientists do not run around declaring that science can explain everything. For example, no one of us claims that science can explain love or hate or beauty or valor or cowardice. But as science advances, these notions may indeed come into the experimental purview of science, just as so many previously intractable subjects have done in the past. This is not an absolute faith as you describe it, it is a prevailing confidence based on past performance of the methods and tools of science.

I note further that religion-bashing occurs primarily among atheists and not by scientists (while there is, of course, some overlap, the loudest atheists are generally not scientists). And yet, my read of modern culture tells me that attacks by religion on science are vastly more common than the reverse, contrary to your statement. Recently in Georgia, the school board wanted to put a disclaimer sticker on biology textbooks. But you do not find scientists asking for disclaimers to be affixed to Bibles in church. The most visible anti-religion scientist I know is the physicist Steven Weinberg. And he is far outnumbered by pro-spiritual scientist/writers such as Paul Davies, Robert Jastrow, and John Polkinghorne. And may I remind you that in the famous Scopes “monkey” trial,* the science teacher lost the case.

2.What’s your honest opinion as to why we are here?

2.I never think much about “why.” Why implies purpose set by external forces. I have always felt that purpose is not defined outside of ourselves, but from deep within. My purpose in life is to lessen the suffering of others; advance our understanding of the universe; and enlighten others along the way.

We are born alone, we die alone. It’s what we do that makes the only things we take with us.

On my deathbed, one thought I will surely have comes from the evolutionary biologist Richard Dawkins. He notes that we who die are the lucky ones. Most people—most genetic combinations of who could ever exist—will never be born, and so will never have the opportunity to die.

When we die, our chemical processes (the metabolism) ceases to function and we immediately begin to lose energy to the air as our body cools. The rest of our body makes tasty food for microorganisms that are already in our body as well as others that are attracted to it, such as fly larvae, worms, etc. Over time, the entire energy content of our body returns to the Earth and the atmosphere from which it came. If you are cremated, none of this energy is made available to nature even though we had been drawing from nature for our entire life for sources of food. When you are cremated, the stored chemical energy gets released into the atmosphere, heats the air, and then radiates energy into space. For this reason, it is my strong preference to be buried, completing the cycle of energy that began with my birth.

So I could not disagree more with your contention. The facts of how society works argue strongly against it. To the extent that you represent an otherwise non-vocal minority, I am intrigued by the strength of your conviction. We live in a wealthy nation. The wealthiest the world has ever known. In some ways, we define our culture (passively or actively) by what we do as a nation as expressed through congressional funding priorities. The National Endowment for the Arts is funded because it contributes a dimension to the quality of life we enjoy as Americans. Transportation is funded (even subsidized) because we value the economic vitality that it brings. The National Science Foundation is funded because it drives basic research that, history has shown, is a foundation of technological progress, especially where corporate R&D does not go. The Smithsonian is funded because we value the preservation of who and what we have been, to ourselves and to the world. The military is funded because we (as a nation) value above all else the real or perceived security it brings. The National Institutes of Health is funded because we care greatly about curing disease—and on and on. It is this mixture that defines America as a nation.

For any unique event, there will always be elements that one cannot explain, since they occur without precedent. But one must always recognize the difference between knowing that something is true, knowing that something is not true, and not knowing one way or another. It’s the not knowing part that leaves singular events susceptible to inventive accounts (especially from conspiracy theorists) of what may have happened. And, of course, conspiracy theorists know the answers before they investigate, which contaminates their analysis—seducing them to accept what supports their thesis and reject or ignore or not notice that which conflicts with it. This psychological effect is well known in research communities, which is why peer-review is so important.

The capacity of the human mind to believe, in the absence of tangible evidence, knows no bounds. Those who wrote to me about their beliefs, in almost all cases, were trying to win me over to their side, but were also authentically curious. As an educator, I had no hesitation engaging them, but I’m also genuinely curious about all the ways a person’s mind can be wired for thought in our perennial attempt to make sense of the world.

Real photo. Real object in our Milky Way galaxy called the “Helix Nebula,” a.k.a.ngc7293. Taken by the Hubble Space Telescope. The urge to look up, see something beautiful, and call it God is strong. In the first century AD, the famous astronomer and mathematician Claudius Ptolemy felt that way as he studied the motions of the planets against the background stars and penned: “When I trace at my pleasure the windings to and fro of the Heavenly Bodies, I no longer touch earth with my feet. I stand in the presence of Zeus himself, and take my fill of ambrosia.”† One of my favorite quotes of all time. What has always intrigued me, however, are all the other things that go on in nature, in this same universe, yet people do not feel compelled to wax poetic about the majesty of God. Like rapid-growth cancer cells, fatal birth defects, killer tsunamis, killer earthquakes, killer volcanoes, killer hurricanes, killer asteroids, the Ebola virus, lethal parasites, malaria-carrying mosquitoes, plague-carrying rats, Lyme disease, heart disease, stroke, appendicitis, species extinction . . . the list is long—practically endless. And how about the equally long list of ghastly things to look at in nature? Such as a close-up image of the dust-mite, or a close-up view of the underbelly of a tarantula, or the sucking jaws of a leech, or the slimy trail of a banana slug, or the flea-infested underbelly of a dog . . . and so forth. So when I see the Helix nebula, I simply see a strikingly beaut...

As for saying your prayers, just in case, it reminds me of a story about the horseshoe that hung in Niels Bohr’s office. This famous physicist was asked why he, a man of science, believed in such superstitious things. He’s rumored to have replied, “They tell me it works even if you don’t believe in it.”

Your point of view derives, of course, from the Judeo-Christian Bible (the Old Testament). The problem here is that plenty of people in the world who are religious believe something else, expressing no less confidence than you do in their specific belief system. The Animists, Buddhists, Confucians, Hindus, Jews, Muslims, Shintoists, Voduns, etc. are each as certain as you that their beliefs are the moral, correct, and only ones to hold. Not to mention the countless sects within Christianity itself, whose beliefs and traditions all differ in important ways: Anglicans, Baptists, Catholics, Episcopalians, Jehovah’s Witnesses, Lutherans, Mormons, Presbyterians, Seventh Day Adventists, and so forth. In the past (and even in the present) differences can drive adherents to commit murder against another sect in the name of their faith. Science, on the other hand, is a system of knowing and discovery that is decoupled from your nationality or birthplace or ancestry or politics or who you worship. It’s a system of knowing the natural world that is immune to opinion, but not to experiment. When you invoke the methods and tools of science, you come up with the origins story as conveyed by scientists. You don’t come up with any faith-based description of the natural world. Had that been the case, then scientists would have been mining religious writings since antiquity for insights into how the physical world works.

the adage, “When an argument last longer than five minutes then both sides are wrong.”

Scientists never “prove” anything. This word has a specific application in mathematics, but in science what we do is demonstrate, with sufficient experiments, that a consensus exists and further evidence in support of an idea would be a waste of effort or funding since other pressing questions remain unanswered. When such an experimental consensus emerges the results will never one day be shown to be wrong. In the modern era of science (the past 400 years) all that happens is that a bigger truth emerges that enclosed the previous ideas and experiments in a deeper understanding.

Dear Mr. Baxter, In my writings (from which the videos are derived) I reference only those who want to bring religious philosophy into the science classroom. This behavior is common for Protestant fundamentalists and largely unheard of in America among Buddhists, Jews, or Muslims, for that matter. Note also that not all belief systems are equal. Most are demonstrably false. The notion that all belief systems are equal is evidence for rampant scientific illiteracy in the nation. And you care about compassion—as we all should. But to be devout in one religion almost always requires that you reject all other religions. Compassion is the last thing you find during Holy Wars. And, of course, the most prominent stories of the Old Testament show anything but compassion. Thank you, Neil deGrasse Tyson

Dear Kevin, Zero chance that Earth is five or six thousand years old. As I say often, if you use religious texts to predict future knowledge of the physical universe, you will get the wrong answer. But it’s not for want of trying. More accurately stated: every previous attempt at this exercise has failed. Consider instead Galileo’s dictum§: “In my mind God wrote two books. The first book is the Bible, where humans can find the answers to their questions on values and morals. The second book of God is the book of nature, which allows humans to use observation and experiment to answer our own questions about the universe.” Galileo was a religious man, but was nonetheless compelled to say: “I do not feel obliged to believe that the same God who has endowed us with senses, reason and intellect has intended us to forego their use and by some other means to give us knowledge which we can attain by them. He would not require us to deny sense and reason in physical matters which are set before our eyes and minds by direct experience or necessary demonstrations.” Just to be clear, the existence or non-existence of God has nothing to do with the age of the Earth. Most (> 80%, is my guess) of western religious people recognize this. Those who link Earth’s age with whether or not God exists are a small minority of the religious community. They just happen to be louder than most others, giving the (false) impression that they are mainstream and represent the majority. There are extensi...

So therein lies a non-convergent point of our conversation: You already know where you want to land. And God is there to design it. I have no idea where I am going to land. And if there is a God of unwavering intelligence, this fact is simply not evident in the book of nature to the unbiased observer. Natural selection never claims perfect design, or even good design, only a design that is more effective than that of a competing species, allowing survival long enough to reproduce. Nothing else matters to the process. Further, I never said the universe was not designed. I simply said that if it was designed, then there is ample (and widely ignored) evidence to demonstrate the designer’s blunders right alongside all those things that are marvelous.

Dear Mark, Often people, especially religious people, look outside themselves to find the meaning of life—in scripture, in messages from religious leaders, religious relics, and so forth. When you do this, and do it for your entire life, it becomes hard to imagine life without this kind of spiritual structure constructed for you and around you. But suppose you instead looked within yourself? By doing so, it’s not hard to find meaning in life by doing meaningful things—caring for others less fortunate than you, raising children, accomplishing hard tasks that give you physical, intellectual, or emotional fulfillment. The drive to do this, without any reference to religious texts at all, can be quite fulfilling. My personal goal is to leave the world a little better off for my having lived in it. The prospect of making this come true drives my work habits daily. For some people, the search for meaning leads to violence, abuse of others, and crime. These people range from selfish to misanthropic. But those traits are not the unique province of non-religious people. The world is no stranger to religious warfare—with abject slaughter of countless innocents in the name of one god or another. So your supposition that one needs God to behave or to give meaning to life—while it may be true for many people—is certainly not a pre-requisite to a fulfilling, law-abiding life. I add that if I help an old lady across the street, it’s because she needs help and I can provide it, not becaus...

Thursday, December 21, 2006 New York Times To the Editor: People cited violation of the First Amendment when a New Jersey schoolteacher asserted that evolution and the Big Bang are not scientific and that Noah’s ark carried dinosaurs. This case is not about the need to separate church and state; it’s about the need to separate ignorant, scientifically illiterate people from the ranks of teachers. Neil deGrasse Tyson New York City

Most things we measure or quantify in everyday life do not span this breadth. So if you get half-off on your store purchase, or if one item is twice as large as another, or if one object moves three times as fast as the other, or contains half as many items, we psychologically think these represent large differences. In astrophysics, however, these differences are small, knowing that the measured properties of things can range by factors of hundreds, thousands, or even billions. When communicating with each other in astrophysics, we invoke high precision only if some other physical quantity depends upon it. Otherwise, the precision is not only distracting, but in most cases, observationally or theoretically unjustified. When the Sun dies, in about five billion years, it will swell to be so large that it will engulf the inner planets. The “edge” of such bulbous entities are actually poorly defined—where is the edge of the cirrus cloud overhead? Where is the edge of the fog through which you drive? The limit of Earth’s atmosphere has no sharp boundary either, so people pick a value that suits their needs. That’s why, if you look up the size of Earth’s atmosphere in multiple (independent) places, you will likely find very different answers, none of which are wrong. In another example, a question as simple as, “how many planets are there in the solar system?” does not have an unambiguous answer. Six moons, including our Moon, are bigger than Pluto. Not only that, several objec...

Newly born children do not arrive with instruction manuals. And while hundreds of professions require that you become pre-certified, a new parent, with no experience at all, is expected to raise a healthy, productive child by what amounts to on-the-job training. This fact magnifies the value of shared wisdom among parents, all trying to do the best job they can. At times, the challenges to success can seem endless.

Teaching someone how to think is hard, and takes more effort on the part of the teacher and student. Among other things, it encourages them to ask questions. It involves being comfortable with ignorance, if that happens to be our collective state of knowledge at the time. It involves experiment and inquiry.

If they believe something in the absence of evidence, I ask them, “Why do you believe this?” or “How do you know this?”

By the way, religious documents are generally referred to as “revealed truths.” And true believers of them hold those documents to be divine and unerring. This has caused nothing but trouble in the history of human culture, particularly when two different religious groups hold conflicting ideas of what is “truth.” So, in my judgment, the word “truth” will not serve your child’s needs as much as the word “investigate,” or, better yet, the word “explore.”

Friday, January 27, 2016 Video Letter to the Rapper B.o.B. Delivered on The Nightly Show with Larry Wilmore, Comedy Central Listen, B.o.B., once and for all, Earth looks flat because, (1) you’re not far enough away at your size, and (2) your size isn’t large enough relative to Earth to notice any curvature at all. It’s a fundamental fact of calculus and non-Euclidean geometry that small sections of large curved surfaces will always look flat to little creatures that crawl upon it. But this whole thing is just the symptom of a larger problem. There is a growing anti-intellectual strain in this country that may be the beginning of the end of our informed democracy. Of course, in a free society you can and should think whatever you want. And if you want to think the world is flat go right ahead. But if you think the world is flat and you have influence over others, then being wrong becomes being harmful to the health, the wealth, and the security of our citizenry. Discovery and exploration got us out of the caves and each generation benefits from what previous generations have learned. Isaac Newton said, “If I have seen farther than others it is by standing on the shoulders of giants.” So that’s right, B.o.B., when you stand on the shoulders of those who came before, you might just see far enough to realize the earth isn’t f%@#king flat. And by the way, this is called gravity. . . . << Mic Drop >>

If anybody cares about my opinion, I note here that in countries founded on freedom, and where there is resistance to government control of its citizenry (such as the USA), it may be easier to engineer solutions to problems than to get a hundred million people to change their behavior. A possible solution, for which there has been great progress, is the laboratory manufacture of meat proteins, where a person can enjoy a steak that never came from any living creature—a topic explored in a highly popular episode of StarTalk that I hosted, featuring the one-and-only Temple Grandin and Paul Shapiro, VP of the Humane Society. So, I don’t quite know what to say to people who react explosively in the face of objective truths, attacking the person who delivers the information. But what’s clear is that we now live in a world where differences of opinion lead to fights rather than conversations.

If you want to write a book, make a film, or engage in a public art project, and if this work makes reference to the natural world, all I ask is that you call your neighborhood scientist and chat about it. When you seek “scientific license” to distort the laws of nature, I would prefer you did so knowing the truth, rather than inventing a storyline that is cloaked in ignorance. You may be surprised to learn that valid science can make fertile additions to your storytelling—whether or not your artistic objective is to destroy the world.

Your stories and perspectives about navigating the people, politics, funding streams, and legacies of institutions deeply informed my (successful) efforts to create, from whole cloth, a brand new Department of Astrophysics at the American Museum of Natural History. You taught me that in life, it’s not good enough to be right. You also must be effective. For that, I now count the formation of that department as one of the highest achievements of my professional career. So Dad, this “thank you” letter in death is simply public notice of what I’ve already thanked you for in life: bestowing upon me guiding principles for living my life to the fullest, and along the way, when possible, lessening the suffering of others. I know I will miss you, because I already do.