Knocking on Heaven's Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World - Lisa Randall (2011)



I first heard the phrase “knockin” on heaven’s door” when listening to the Bob Dylan song at his 1987 concert with the Grateful Dead in Oakland, California. Needless to say, the title of my book is intended differently than the song’s lyrics, which I still hear Dylan and Jerry Garcia singing in my head. The phrase differs from its biblical origin as well, though my title does toy with this interpretation. In Matthew, the Bible says, “Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you: For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened.”21

According to these words, people can search for knowledge, but the ultimate object is to gain access to God. People’s curiosity about the world and active inquiries are mere stepping-stones to the Divine—the universe itself is secondary. Answers might be forthcoming or a believer might be spurred to more actively seek truth, but without God, knowledge is inaccessible or not worth pursuing. People can’t do it on their own—they are not the final arbiters.

The title of my book refers to science’s different philosophy and goals. Science is not about passive comprehension and belief. And truth about the universe is an end in itself. Scientists actively approach the door to knowledge—the boundary of the domain of what we know. We question and explore and we change our views when facts and logic force us to do so. We are confident only in what we can verify through experiments or in what we can deduce from experimentally confirmed hypotheses.

Scientists know a remarkable amount about the universe, but we also know that much more remains to be understood. A great deal remains beyond the reach of current experiments—or even any experiment we can dream of. Yet despite our limitations, each new discovery lets us advance another rung in our ascent toward truth. Sometimes a single step can have a revolutionary impact on the way we see the world. While acknowledging that our ambitious aspirations are not always satisfied, scientists steadfastly seek access to a richer understanding as advancements in technology make more of the world’s ingredients accessible to our gaze. We then search for more comprehensive theories that can accommodate any newly acquired information.

The key question then: who has the capacity—or the right—to look for answers? Do people investigate on their own or trust higher authorities? Before entering the world of physics, this part of the book concludes by contrasting the scientific and religious perspectives.


We’ve seen that in the seventeenth century, the ascent of scientific thinking splintered the Christian attitude to knowledge—leading to conflicts between different conceptual frameworks that continue to this day. But a second source of division between science and religion was about authority. In the eyes of the church, Galileo’s claim to be able to think for himself and presume the capacity to independently understand the universe deviated too far from Christian religious belief.

When Galileo pioneered the scientific method, he rejected a blind allegiance to authority in favor of making and interpreting observations on his own. He would change his views in accordance with observations. In doing so, Galileo unleashed a whole new way of approaching knowledge about the world—one that would lead to much greater understanding of and influence over nature. Yet despite (or more accurately because of) the publication of his major advances, Galileo was imprisoned. His openness in his conclusion about the solar system saying that the Earth is not the center was too threatening to the religious powers of the time and their strict interpretation of scripture. With Galileo and other independent thinkers who precipitated the scientific revolution, any literal biblical interpretation of the nature, origin, and behavior of the universe had become subject to refutation.

Galileo’s timing was especially poor since his radical claims coincided with the heyday of the Counter-Reformation, the Catholic Church’s response to its Protestant offshoots. Catholicism felt itself seriously threatened then by Martin Luther’s advocacy of independent thought and interpreting scripture by looking directly to the text, rather than through an unquestioning acceptance of the church’s interpretation. Galileo supported Luther’s views and went even a step further. He rejected authority and furthermore explicitly contradicted the Catholic interpretation of religious texts.22 His modern scientific methods were based on direct observations of nature that he then tried to interpret with the most economical hypotheses that could account for the results. Despite Galileo’s devotion to the Catholic Church, his inquisitive ideas and methods were too similar to Protestant thinking in the clergy’s eyes. Galileo had inadvertently entered into a religious turf war.

Ironically, the Counter-Reformation might nonetheless have inadvertently precipitated Copernicus’s espousal of a heliocentric universe. The Catholic Church had wanted to ensure that its calendar was reliable so that celebrations would occur at the right time of year and its rituals would be properly maintained. Copernicus was one of the astronomers asked by the church to attempt to reform the Julian calendar to make it more compatible with the motion of the planets and the stars. It was this very research that led him to his observations and ultimately to his radical claims.

Luther himself did not accept Copernicus’s theory. But neither did most anyone else until Galileo’s advanced observations and ultimately Newton’s theory of gravity validated it later on. Luther did, however, accept other advances made in astronomy and medicine, which he found consistent with an open-minded appreciation of nature. He wasn’t necessarily a great scientific advocate, but the Reformation created a way of thinking—an atmosphere where new ideas were discussed and accepted—that encouraged modern scientific methods. Thanks also in part to the development of printing, scientific as well as religious ideas could rapidly spread and diminish the authority of the Catholic Church.

Luther held that secular scientific pursuits were potentially as valuable as religious ones. Scientists such as the great astronomer Johannes Kepler felt similarly. Kepler wrote to Michael Maestlin, his former professor at Tubingen, “I wanted to become a theologian, and for a long time I was restless. Now, however, observe how through my effort God is being celebrated in astronomy.” 23

In this view, science was a way of acknowledging the spectacular nature of God and what he created and the fact that explanations for how things worked were rich and varied. Science became a means of better understanding God’s rational and orderly universe, and furthermore helping humankind. Notably, early modern scientists, far from rejecting religion, construed their inquiry as a form of praise for God’s creation. They viewed both the Book of Nature and the Book of God as paths to edification and revelation. The study of nature in this view was a form of gratitude and acknowledgment to their creator.

We occasionally hear this viewpoint in more recent times as well. The Pakistani physicist Abdus Salam, during the speech he gave when receiving the 1979 Nobel Prize for his role in creating the Standard Model of particle physics, asserted, “The Holy Prophet of Islam emphasized that the quest for knowledge and sciences is obligatory upon every Muslim, man and woman. He enjoined his followers to seek knowledge even if they had to travel to China in its search. Here clearly he had scientific rather than religious knowledge in mind, as well as an emphasis on the internationalism of the scientific quest.”


Despite the essential differences the last chapter described, some religious believers are happy to apply the scientific and religious parts of their brains separately and continue to view understanding nature as a way of understanding God. Many who don’t actively pursue science too are happy to allow scientific progress to proceed unfettered. Still, the rift between science and religion nonetheless persists for many in the United States and other parts of the world. It occasionally expands to the point where it causes violence or at the very least interferes with education.

From the point of view of religious authority, challenges to religion such as science can be suspect for many reasons, including some that have nothing to do with truth or logic. For those in charge, God can always be invoked as the trump card that justifies their point of view. Independent inquiry of any kind is clearly a potential threat. Prying into God’s secrets might furthermore undermine the moral power of the church and the secular authority of the rulers on Earth. Such questioning could also interfere with humility and community loyalty, and might even lead one to forget God’s importance. No wonder religious authorities are sometimes worried.

But why do individuals align themselves with this point of view? The real question for me is not what the differences are between science and religion. Those can be reasonably well delineated as we argued in the previous chapter. The important questions to answer are these: Why do people care so much? Why are so many people suspicious of scientists and scientific progress? And why does this conflict over authority erupt so often and even continue to this day?

It so happened that I was on a mailing list for the Cambridge Round-table on Science, Art and Religion, a series of discussions among Harvard and MIT affiliates. The first one I attended, on the topic of the seventeenth-century poet George Herbert and the New Atheists, helped shed some light on some of these questions.

Stanley Fish, the literary scholar turned law professor, was the principal speaker at the event. He began his remarks by summarizing the views of the New Atheists and their antagonism toward religious faith. The New Atheists are those authors, including Christopher Hitchens, Richard Dawkins, Sam Harris, and Daniel Dennett, who have countered religion with harsh and critical words in bestselling books.

After his brief report of their views, Fish proceeded to criticize their lack of understanding of religion, a perspective that seemed to fall on a receptive audience since I think as a nonbeliever I was in the minority at the discussion. Fish argued that the New Atheists would have a stronger case if they had considered the challenges to self-reliance that religious faithful have to contend with.

Faith requires active questioning, and many religions demand it of the observant. Yet at the same time, many religions, some branches of Protestantism among them, call for a rejection or suppression of independent will. In Calvin’s words: “Man by nature inclines to deluded self-admiration. Here, then, is what God’s truth requires us to seek in examining ourselves: it requires the kind of knowledge that will strip us of all confidence in our own ability, deprive us of all occasion for boasting, and lead us to submission.”24

These particular words applied primarily to moral questions. But the belief in the necessity for external guidance is unscientific, and it can be difficult to know where to draw the line.

The struggle between the desire for knowledge and the mistrust of human pride reverberates throughout religious literature, including the Herbert poems that Fish and the Roundtable participants discussed. The Cambridge conversation elaborated on Herbert’s inner conflicts about his relationships with knowledge and with God. For Herbert, self-generated understanding was a sign of sinful pride. Similar warnings appear in the writings of John Milton. Although he firmly believed in the necessity for robust intellectual inquiry, he nonetheless has Raphael tell Adam in Paradise Lost that he should not inquire too curiously into the motion of the stars, for “they need not thy belief.”

Surprisingly (at least to me), notable representatives of our group of Harvard and MIT professors in attendance at the roundtable event approved of Herbert’s attempts at self-renunciation, believing it was a good thing to suppress one’s individuality and align oneself with this greater force. (Anyone who knows Harvard and MIT professors would also be surprised at this alleged denial of ego.)

Maybe the question of whether people can access truth on their own is the real issue at the heart of the religion/science debate. Is it possible that the negative attitudes toward science we hear today are partially rooted in the admittedly extreme beliefs expressed by Herbert and Milton? I’m not sure we are arguing so much about how the world came to be as about who has a right to figure things out and whose conclusions we should trust.

The universe is humbling. Nature hides many of its most interesting mysteries. Yet scientists are arrogant enough to believe we can solve them. Is it blasphemous to search for answers or is it merely presumptuous? Einstein as well as the Nobel Prize—winning physicist David Gross described scientists as thinking they are wrestling with God in order to learn the answers to the big questions about how nature works. David certainly didn’t mean this literally (and certainly not humbly)—he was recognizing our miraculous ability to intuit the world around us.

This legacy of not trusting our ability to figure things out for ourselves continues in other respects as well, when we see it in humor, movies, and a good deal of today’s politics. Sincerity and respect for facts have become somewhat unfashionable in our ironic and often anti-intellectual era. The degree to which some people will go to deny the successes of science can be amazing. I was once at a party where I met someone who boldly insisted to me that she didn’t believe in science. So I asked her whether she had taken the same elevator to the eleventh floor that I had. Did her phone work? How did her electronic invitation reach her?

Many people still consider it embarrassing or at best quaint to be earnest about facts or logic. One source of anti-intellectual antiscientific sentiment might be resentment at the act of egotism in a person feeling powerful enough to tackle the world. Those who have an underlying sense that we don’t have the right to take on enormous intellectual challenges believe these are the domain of higher powers than we possess. This peculiar anti-ego, anti-progress trend can still be heard in the playground and the country club.

For some individuals, the idea that you can decipher the world is a source of optimism and leads to a sense of greater understanding and influence. But for others, science and scientific authorities who know more and have greater skill in these technical areas are a source of fear. People divide themselves according to who feels qualified to engage in scientific activities and to evaluate scientific conclusions, and who feels left out and powerless in the face of scientific thought and therefore views such pursuits as acts of ego.

Most people want to feel empowered and to experience a sense of belonging. The question each individual faces is whether religion or science offers a greater sense of control over the world. Where do you find trust, comfort, and understanding? Do you prefer to believe that you can figure things out for yourself or at least trust fellow humans to do so? People want answers and guidance that science can’t yet provide.

Nonetheless, science has told us much about what the universe is made of and how it works. When you put together all of what we know, the picture scientists have deduced over time fits together miraculously well. Scientific ideas lead to correct predictions. So some of us trust in its authority, and many recognize the remarkable lessons of science through the ages.

We constantly move beyond human intuition as we explore regions to which we don’t have immediate access, and we have yet to make discoveries that bring back the centrality of humans in our description of the world. The Copernican revolution consistently repeats itself as we realize how we are just one of many sets of objects of a random size in a random place in what appears—in the scientific viewpoint—to be a randomly operating universe.

People’s curiosity and the ability to make progress toward satisfying this hunger for information make humanity very special indeed. We are the one species equipped to ask questions and systematically chip away to find the answers. We question, we interact, we communicate, we hypothesize, we make abstractions, and in all of this we end up with a richer view of the universe and our place within.

This doesn’t mean that science necessarily will answer all questions. People who think science will solve all human problems are probably on the wrong track as well. But it does mean that the pursuit of science has been and will continue to be a worthwhile endeavor. We don’t yet know all the answers. But scientifically inclined people, whether or not they have religious faith, try to pry open the universe and find them. Part II explores what they’ve found so far and what’s now on the horizon.