What may have Existed Before the Universe

Is close your eyes for a moment and try to picture nothing. Not darkness because darkness is something. Not empty space because space is something too. Is not silence because silence is the absence of sound within an environment that can hold sound. Try to picture the absolute total complete absence of everything. No matter is no energy, no space, no time, no laws of physics uh waiting to be applied, no quantum fields humming at their lowest energy state is not even the concept of here or there or when is um you can't do it, can you? Is your mind keeps sneaking something back in. A void, a blackness, a sense of waiting, but all of those are still something.

Is the the human mind is fundamentally incapable of imagining genuine nothingness because every act of imagining requires a mental space in which the imagining takes place is and and that mental space is already something is We are creatures of the universe built from the universe shaped entirely by a reality in which something has always been the baseline condition is nothingness is not in our cognitive repertoire is. And yet here is where it gets extraordinary that incapacity doesn't stop us from asking the question is it doesn't stop us from standing at the edge of everything we know and peering over into the abyss and asking was there ever truly nothing or was there always something is and if there was something before the universe we know before the big bang for spacetime itself. What on earth or rather what beyond earth is could that something possibly have been is this is the question not just what caused the big bang though that's part of it is not just was there a time before time though that too is embedded in it is the full uncompromising version of the question is this in the absence of our universe in the absence of space and time as we understand them. Is in the absence of the physical laws that govern everything we have ever observed or measured. Was there anything? And if so, what was its nature? Is we're going to chase that question today? Um, honestly, carefully, and with the full acknowledgement that we will not arrive at a definitive answer because no one has. But the journey itself will take us through some of the most astonishing ideas in all of modern physics and cosmology is it will take us to the frontier where science becomes almost indistinguishable from philosophy and where both disciplines are humbled by the sheer depth of what they don't yet know is Neil deGrasse Tyson astrophysicist science communicator is and one of the most compelling public voices for the beauty of the cosmos has returned to this question repeatedly throughout his career always with the same essential posture is intellectual honesty wrapped in genuine wonder. He doesn't pretend to have the answer is but he makes the not having of the answer feel like the most alive most human most thrilling place it is possible to stand is that posture is the spirit of this entire conversation is let's go Neil deGrasse Tyson is the director of the Hayden Planetarium at the American Museum of Natural History in New York City is he holds a doctorate in astrophysics from Columbia University and has spent decades at the intersection of serious scientific research and public education. Is he has authored numerous books on the universe. Um hosted the revived version of Carl Sean's landmark documentary series Cosmos is and appeared in more public conversations about science than perhaps any other researcher alive today. Is what sets him apart is not simply his credentials uh impressive as they are. It is it is his extraordinary ability to take the most abstract concepts in physics and make them land emotionally and intellectually on audiences with no scientific background. Is he speaks about the cosmos with a kind of reverent urgency as if the ideas are too important, too beautiful and too relevant to everyday human life to be kept inside academic journals. Is he treats scientific ignorance not as a moral failure but as the natural starting point for every honest inquiry. And he treats the unknown not as a void to be feared is but as a space to be explored with curiosity and rigor. And the question of what may have existed before the universe is precisely the kind of territory he finds most alive is before we can talk about what might have existed before the universe. We need to be clear genuinely clear is not pop science clear about what the universe means in this context is in everyday language the universe means everything. All of it is the planets and stars and galaxies, the black holes and nebula, the dark matter and dark energy, the light traveling across billions of light years, the atoms in your body is the air in your lungs. When most people say the universe, they mean the totality of physical existence is but cosmologists are more precise. Is when they speak of our universe, they mean a specific spaceime, a specific four-dimensional fabric of space and time that came into existence approximately 13 is 8 billion years ago in the event we called the big bang. That spacetime has a particular geometry, a particular set of physical laws, uh a particular history. It is not infinite in time. It had a beginning is and that beginning that first moment of our space-time's existence is the boundary beyond which the question what existed before the universe points is here's the first and most important conceptual challenge. The Big Bang was not an explosion that happened inside a pre-existing universe is it was not a fireball expanding into an empty void that was already there waiting. The big bang was the beginning of space itself and not just spaceime as well is um according to Einstein's general theory of relativity space and time are not separate independent containers for the universe's contents is they are a unified dynamic fabric spacetime that participates in the physics of the universe is and that fabric according to our best models came into existence at the big bang is if that is true and the observational evidence is genuinely compelling then before the big bang is not a well-defined concept using ordinary temporal language is time began at the big bang there was no before in any conventional sense because before required There's time in which to exist and time didn't exist yet. Is asking what came before the big bang may be structurally similar to asking what lies north of the north pole. At the pole itself every direction is south. Is the concept of north simply doesn't apply. Similarly at the origin of time before may simply not apply is and yet and this is crucial the fact that the question is linguistically awkward doesn't mean it's physically meaningless is it might mean that we need better language better concepts uh better framework to ask it properly is because even if time as we know it began at the big bang that doesn't automatically mean that nothing whatsoever existed in any sense outside of or prior to our spaceime is it means our usual way of describing prior existence breaks down and we need to think more carefully is what would it even mean for something to exist before time. This is not a trivial question and sitting with it seriously changes the entire nature of the inquiry. Is ordinarily when we say something exists we mean it occupies some region of space and persists through some duration of time. Is a chair exists because it takes up space and continues to be there moment after moment. An atom exists because it has a position and a set of quantum properties that persist in time is even events which are more momentary exist within a temporal framework. Existence in every case we have experience with is inextricably bound up with time is. So what does it mean to exist in the absence of time? Is existence without time even a coherent concept? Is this is where physics and philosophy become genuine partners rather than rivals? Because neither can answer this alone. Is one way to approach it is to ask whether existence can be defined in purely relational or structural terms without reference to temporal persistence. is mathematics offers a provocative model here. The number seven exists in some meaningful sense. It has properties. It stands uh in relationships to other mathematical objects. Is it is described by truths that don't depend on any particular moment in time. Is the Pythagorean theorem was true before any human being discovered it. It will be true after humanity is gone. It's truth does not depend on being situated within a time stream. Is mathematical objects if they exist at all exist timelessly as pure structure pure relationship. Is some physicists and philosophers of physics have seriously proposed that something like this might be relevant to the question of what preceded the universe. Is perhaps what existed before the big bang or more accurately is uh what exists outside our particular spaceime is something more like a mathematical structure than a physical substance. Not matter, not energy, not a field is but a landscape of possible structures each of which corresponds to a possible universe existing in something like the way mathematical truths exist. Not in time, not in space is but as features of a deeper, more abstract layer of reality. Is this idea associated with the work of the physicist and mathematician Max Taggmark among others is provocative enough to be uncomfortable is but discomfort is not a disqualification in physics the history of science is littered with ideas that seemed absurd until they turned out to be true is now let's move from conceptual groundwork work into the specific scientific models that physicists have proposed to describe what might have preceded or generated our universe is these are not speculations in the casual sense of the word. They are mathematically rigorous internally consistent frameworks developed by serious researchers. None of them are confirmed is all of them remain provisional but they represent the genuine frontier of human knowledge on this question is the first possibility is eternal inflation is in the 1980s MIT physicist Alan Guth proposed that the very early universe underwent a brief but extraordinarily rapid period of exponential expansion. Called cosmic inflation. As this period lasted a fraction of a second but expanded the universe by an almost incomprehensible factor, smoothing out irregularities and seeding the large scale structure we observe today. Is inflation explains several otherwise puzzling features of the cosmos. Its geometric flatness, its remarkable uniformity on large scales is the specific pattern of temperature fluctuations in the cosmic microwave background is. But here's the extension that bears directly on our question. In many versions of inflation theory, the inflationary process doesn't simply start and stop uniformly everywhere. Is quantum fluctuations in the field driving inflation cause it to end in some regions while continuing in others. Is the regions where it ends become bubble universes expanding, cooling, developing physical laws and constants. Each a separate cosmos potentially with different properties is the regions where inflation continues keep expanding exponentially spawning new bubble universes indefinitely. The result is an eternal inflationary background, a vast, possibly infinite substrate that never fully stops inflating, continuously generating new universes. Is in this picture. What existed before our big bang was the eternal inflationary background itself. Our universe is not the beginning of everything. Is it's a local event, a nucleation, a phase transition within a much larger structure that may have no beginning of its own. Is what preceded the big bang was a roing quantum mechanical sea of inflating spaceime pregnant with the potential for new universes at every moment. The second possibility related but distinct is the multiverse more broadly conceived. The eternal inflation picture is one version of a multiverse. But there are others is in some formulations of string theory. The leading candidate for a theory of quantum gravity. The equations permit an astronomically large number of different stable configurations of the is fundamental fields. Each configuration corresponds to a different set of physical laws, different particle masses, different strengths of the fundamental forces. Is the the landscape of string theory as it's called might contain something on the order of 10 ^ of 500 distinct possible universes each with its own physics. Is in this landscape picture. Our universe is one solution among staggeringly many. Not because there's anything special about it, but because we could only exist in a universe compatible with the existence of complex life is the vast majority of universes in the string landscape may contain no stars, no chemistry, no structure at all. But here we are in one of the rare ones that does this. And what preceded our universe in this picture is not time, not a prior state is but something more like possibility space, a mathematical landscape of potential physical realities each of which can in principle be actualized. The third possibility is the quantum vacuum. This is perhaps the most misunderstood concept in all of popular physics and it deserves careful treatment. Is in quantum mechanics the vacuum empty space at its lowest energy state is not nothing. It is a seething dynamic medium filled with quantum fluctuations. Is virtual particles pop in and out of existence continuously too briefly to be directly observed but real enough to produce measurable physical effects is the case effect which can be measured in the lab is a direct consequence of quantum vacuum fluctuations. The lamb shift in atomic energy levels is another is some physicists most notably Alexander Valenin and Lawrence Krauss and different formulations have proposed that the universe could have arisen from a quantum fluctuation of the vacuum is not from nothing in the absolute philosophical sense but from a quantum vacuum. A state with no matter no radiation, no classical spacetime is but with the quantum fields and physical laws that govern the behavior of fluctuations. In this picture is the big bang was a spontaneous quantum event, a tunneling process in which a tiny seed of spaceime nucleiated out of the vacuum and then inflated into the universe we now inhabit. Is this is an extraordinarily subtle idea and it comes with genuine philosophical complications. Is critics including the philosopher David Albert have argued that a quantum vacuum is emphatically not nothing and that describing the universe's origin as arising from is nothing in this context is a significant conflation of physics with metaphysics. They're not wrong. Is a quantum vacuum is a very specific physical object governed by very specific physical laws. Calling it nothing stretches the word to the breaking point is but the physicists making this argument are not naive about the conflation is their point is narrower and more technical given the quantum vacuum and its properties. The spontaneous nucleation of a universe is not merely possible. It may be inevitable. Is given enough time in whatever sense time applies outside our spaceime is the question of why there is a quantum vacuum rather than nothing is a separate question and they are mostly honest about not having answered it. Is the fourth possibility is the cyclic universe is this is one of the oldest cosmological intuitions in human thought. The idea that the universe doesn't have a single absolute beginning and end but cycles is in modern versions the most mathematically developed of which is the epyodic model proposed by Paul Steinhart and Neil Turk is the big bang was not the beginning of everything but a collision a violent interaction between two higher dimensional surfaces called brains is embedded in a higher dimensional case. That collision generated the heat, the energy and the initial conditions we associate with the big bang is. And crucially, it was not the first such collision. The brains oscillate, approach each other, collide, retreat, and return in a potentially endless cycle of big bangs and expansions and eventual contractions. Is what existed before our big bang in this picture was the previous cycle. A previous expansion, a previous era of cosmological history is um separated from ours by a bounce rather than an absolute beginning. Is the fifth possibility comes from loop quantum cosmology which is one specific approach to the broader problem of quantum gravity is um in ordinary general relativity the big bang singularity is a genuine mathematical breakdown a point at which density and curvature become infinite and the theory fails is but in loop quantum cosm mology. The fundamental structure of spaceime is quantized at the plank scale and this quantization prevents true singularities from forming is instead of an infinite crunch there is a quantum bounce. The universe contracts to a minimum size and then reexpands is in this framework. Before the big bang, there was a contracting universe in its own era of history which reached a quantum minimum and bounced into our current expansion. Is what existed before the universe was in some sense another version of the universe contracting where ours is expanding, compressing where ours is cooling is but governed by the same fundamental physics is each of these possibilities is remarkable in its own right and each of them transforms the question what existed before the universe is from from a mystery with no traction into a scientific question with specific testable implications at least in principle is the gravitational wave background. The polarization patterns in the cosmic microwave background is the large scale structure of the observable universe. All of these carry faint imprints of whatever came before the big bang. If anything did is we are not necessarily forever blind to the pre-universal past is we are simply at an early stage of developing the instruments and the theoretical frameworks needed to read what's written there is running through all of these models is a common obstacle. Quantum gravity is this is the great unfinished project of fundamental physics and it sits squarely at the center of the question we're exploring is Einstein's general relativity describes gravity and through gravity the large scale structure of spaceime with extraordinary precision is it has been tested and confirmed in hundreds of independent ways from the bending of light around the sun to the detection of gravitational waves from merging black holes. This um it is one of the most successful physical theories ever developed. Is quantum mechanics on the other hand describes the behavior of matter and energy at the smallest scales with equally stunning precision is it underlies the operation of every transistor in every computer ever built. It explains the structure of atoms and molecules, the behavior of light, the properties of materials is it has never failed an experimental test. It too is one of the most successful physical theories ever developed. Is and and these two extraordinary theories are fundamentally incompatible is they rest on different mathematical structures make different assumptions about the nature of reality. And when you attempt to combine them to describe gravity at quantum scales is which is exactly what you must do to describe the very beginning of the universe. The mathematics breaks down. You get nonsense. Infinite energies where finite energies should be. There's zero probabilities where nonzero probabilities are required. The equations stop producing physically meaningful predictions. Is the singularity at the big bang. That point of theoretically infinite density and temperature is almost certainly not a real feature of the universe. Is um it is almost certainly an artifact of applying the wrong theory in the wrong regime. General relativity is a theory of the large scale is at the extreme densities of the big bang quantum effects must be dominant and general relativity alone cannot give you a correct description. Is what what the singularity tells us is not the universe came from a mathematical point of infinite density. What it tells us is here is where we need a better theory is that better theory quantum gravity would change everything about how we describe the origin of the universe is uh it might reveal that the singularity dissolves into a smooth quantum state with no sharp beginning. It might show that what we call the big bang is actually a bounce from a prior contracting phase is uh it might demonstrate that spaceime itself is emergent that at the plank scale space and time as we know them disappear and give way to something more fundamental is from which our spaceime crystallizes like a phase transition is we don't have that theory yet. String theory is a candidate but it remains unconfirmed by experiment is loop quantum gravity is another candidate with different mathematical foundations and different strengths and weaknesses is there are other approaches causal dynamical triangulations asmtoic safety causal sets uh each represents a serious research program with serious people behind it is none has yet produced a complete empirically tested theory of quantum gravity that remains the frontier is but the frontier is not empty. It is populated by extraordinary ideas some of which we've already discussed is and the direction of travel is clear toward a more complete theory that will eventually perhaps in decades is perhaps in generations tell us something true about what the universe was doing at and before the plank epoch. Something true about what before can possibly mean. Is something true about whether the universe had an absolute beginning or whether it is embedded in a larger structure without one. There's no discussion of what existed before the universe can stay purely within physics. At some point the physics hands the baton to philosophy and that handoff is not a retreat from rigor. It is an acknowledgment that some questions require different kinds of tools. Is the deepest philosophical question lurking here is whether absolute nothingness is even a coherent concept. Is most physicists when pressed will admit that they don't think nothing in the strong metaphysical sense is actually possible. Is a true nothing. No matter no energy, no space, no time, no quantum fields, no physical laws seems not just empirically absent but possibly logically impossible. Is because even to say there was nothing you're using a framework that implies time and time is already something is even to say there was a state of nothingness you're invoking the concept of a state which is already something is the philosopher Godfrey Linets famously asked why is there something rather than nothing it is perhaps the most fundamental question ever posed is and and the disquing possibility is that the question may be malformed. It may be that nothing is not a possible baseline state of reality. Is it may be that existence in some form at some level is not contingent but necessary. That reality could not have been otherwise. That something always had to be is this is not a religious claim and it shouldn't be mistaken for one. It's a philosophical claim with significant scientific implications. Is if existence is necessary, if there could not have been nothing, then the question shifts from why is there something to why is there this particular something? Is why these physical laws? Why this universe with these constants? Why the specific big bang that produced this specific cosmos is and here the multiverse ideas become philosophically relevant in a new way. If there are many possible universes each with different physical laws is and if all possible universes in some sense exist as in the techmark multiverse or the string theory landscape then why this universe is has an anthropic answer. We observe this universe because we could only have evolved in a universe compatible with our existence. Is the question of um why anything exists at all remains open. But the question of why this particular universe is the one we observe is answered by the simple fact that we are here to observe it is this reasoning the anthropic principle is controversial. Many physicists find it philosophically unsatisfying is that that it it feels to some like explaining why you survived the car accident by noting that if you had died you wouldn't be here to ask the question is technically valid but not deeply illuminating. Others argue that anthropic reasoning is a legitimate and underutilized tool in physics is particularly in the context of the fine-tuning of the constants of nature. The mysterious fact that the fundamental constants of our universe appear to be precisely calibrated for the existence of is complex structures like stars, chemistry and life is um the honest answer is that no one has fully resolved this tension. Anthropic reasoning is a powerful tool that is simultaneously legitimate and limited. And the question of why anything exists at all remains perhaps permanently at the edge of what science can address is there is also the profound question of language. Is every word we use to discuss what might have existed before the universe is a word forged in the experience of living inside a universe that has space and time is before existed nothing cause origin. All of these carry implicit assumptions about temporal sequence. This spatial location and causal structure that may simply not apply at the boundary we're trying to describe is we are using tools built for the interior of the house to describe what might be outside the house. And the tools keep failing. Not because the question is stupid is but because the tools weren't designed for this job is mathematicians face a similar problem when they try to intuit it results in highdimensional spaces. Our spatial intuition is built for three dimensions is in four or five or 10 dimensions. The results are often wildly counterintuitive. Not because they're wrong, but because our minds weren't shaped to navigate those spaces. Is the solution is to trust the mathematics and let intuition um follow as best it can. uh accepting that it will sometimes fail entirely is something similar may be required for questions about the pre-universal state is trust the mathematics. Push the equations as far as they will go. Accept that ordinary language will fail at the boundary and remain open to the possibility that the answer is when it comes will not look like anything we currently expect is here is what strikes me as the most important insight in this entire conversation and it's an insight that Tyson has articulated in various forms for decades is the difference between we don't know and it's unknowable is not just a semantic distinction. It is the difference between a living science and a dead one. Is throughout history human beings have repeatedly declared certain questions permanently beyond the reach of knowledge and have repeatedly been proved wrong is we said we would never know what stars are made of. We said we would never know the age of the earth. We said we would never detect gravitational waves is we said we would never observe a black hole directly. Every single one of those declarations of permanent ignorance was eventually overturned by new instruments, new theories, is new conceptual frameworks that hadn't been imagined when the declaration was made. Is the question of what existed before the universe is right now in a regime of genuine scientific uncertainty. Our current theories break down at the plunk epoch is we don't have a confirmed theory of quantum gravity. We cannot directly observe anything from before the big bang in that sense. We don't know is and we don't know is the honest scientifically appropriate thing to say is but that is very different from saying we will never know. It is different from saying the question is permanently sealed. Is um it it is different from saying that no future theory, no future instrument, no future conceptual breakthrough could ever shed light on. It is the cosmic microwave background, the faint afterglow of the early universe's heat detectable in every direction we look once thought to be unobservable. Is we not only observe it now, we have mapped it in extraordinary detail and we read from it the story of the universe's first 380,000 years is uh future observations of the primordial gravitational wave background ripples in spaceime generated in the universe's earliest moments may carry imprints of what happened even earlier is perhaps even of what came before. Future theories of quantum gravity may dissolve the singularity and reveal a smooth classically describable pre- Big Bang state. As future mathematical frameworks may give us the language to describe existence outside of time in a way that is rigorous and coherent is we are not at the end of physics. We are very far from the end of physics is and the question of what existed before the universe is one of the great targets that physics is currently trying to reach is there's something else worth saying here. Something that often gets lost in technical discussions. The emotional and human significance of this question is why do we care what existed before the universe is what does it matter practically speaking whether there was an eternal inflating background or a prior contracting cycle or a quantum vacuum or absolute nothing is it matters because the question of the universe's origin is at the deepest level a question about our own origin. We are made of the universe is we are as has been said many times but never too many times stardust atoms forged in stellar cores and distributed by supernova explosions is assembled by billions of years of chemistry and evolution into temporary structures capable of awareness and curiosity. When we ask what existed before the universe, we're asking what existed before us in the deepest possible sense. Not biologically, not evolutionarily, not historically, but ontologically we are asking about the foundation of our own existence is. And the answer, whatever it turns out to be, will reshape how we understand ourselves in the cosmos. Is not just as inhabitants of a planet, not just as members of a species, not just as products of evolution, but as events in the history of a universe that may itself be an event in the history of something larger, something older, is something so different from what we know that we don't yet have words for it. So let's come to rest here at the edge of everything we know and sit with the question in its full honest unresolved form is what may have existed before the universe is the honest scientific answer is we have serious mathematically grounded possibilities and we don't know which of them if any is correct. There may have been an eternal inflationary background, a vast quantum mechanical substrate of expanding spaceime that never fully stops and from which bubble universes is including ours nucleate endlessly. In this picture, our big bang was not a beginning but a local event in an infinite perhaps eternal landscape. Is there may have been a prior contracting universe, a previous cosmic epoch that compressed to a quantum minimum and bounced into our current expansion in a cycle that may have been going on forever. In this picture, the chain of causality extends backward without a singular origin through an indefinite sequence of cosmic cycles. There may have been a quantum vacuum, not nothing but a state of minimum energy with the quantum fields and laws in place is from which our spacetime nucleated as a spontaneous quantum fluctuation. In this picture, the universe arose not from nothing but from a kind of cosmic restlessness inherent in quantum reality. There may have been nothing that maps onto any of these descriptions because the concept of existence itself may work differently at the boundary of spaceime and what we call before may require entirely new concepts that we have not yet developed is or perhaps and this is the deepest possibility of all the question has a structural flaw at its core. Is perhaps asking what existed before the universe is like asking what's north of the north pole. Is perhaps time had a genuine beginning and before that beginning is a direction that doesn't correspond to anything real. Perhaps the universe is in the deepest sense self-contained without a prior state without an external cause without a before at all. We don't know and we should hold that not knowing with care because it is not a failure. It is the most honest thing we can say. It is the acknowledgment that we are finite minds inside a universe that does not owe us easy answers. Grappling with questions that reach beyond every framework we have yet built to understand them. Neil deGrasse Tyson has spent his career making exactly this point in a thousand different ways. That the universe is under no obligation to make sense to us is that the limits of our understanding are not the limits of reality. Is that we don't know is the beginning of the most important kind of work there is not the end of it. Is think about what it means that you're here watching this wrestling with these ideas is think about the long chain of human inquiry that made this conversation possible. Every philosopher who asked why there is something rather than nothing is every astronomer who mapped the night sky, every physicist who pushed the equations one step further toward the unknown. You are part of that chain. Not passively is not just as a consumer of ideas as but as a mind that has now been stretched a little further. That now holds the question a little more clearly that now understands a little better why the question is hard is the universe is 13.8 billion years old. As far as we can measure is what came before that age, before that history, before that spaceime, before that particular arrangement of quantum fields and physical laws may have been something is or may have been the kind of nothing that turns out to be impossible. Or may have been a reality so different from ours that the word something doesn't quite fit either is we stand at the edge. We look over. We don't see all the way down is but we keep looking is and that the looking the refusing to look away is the insisting on asking even when the question resists every answer we try to give it. That might be the most distinctly human thing there is the edge is not where things end. Is it's where they get interesting.