The single most amazing fact about the Universe

Out there in the Universe, there are plenty of amazing things waiting to be discovered. At every level of reality, there’s a great set of mysteries, puzzles, and facts just waiting for us to uncover them, find them out, and look to put them together in an increasingly accurate, precise, and powerful picture of what reality actually is. In space, we can look to greater distances, earlier times, longer-or-shorter wavelengths of light, or even beyond the concept of light itself to reveal nature’s grandest secrets. Here on Earth, we can examine any material system we like — in any state of matter, living or non-living, at any scale we dare to probe — and reveal its inner workings, all the way down to the limits of our capabilities to probe subatomic scales.

And yet, there’s one simple fact about the Universe that goes deeper than the profundity of any individual aspect of reality that we might seek to elevate: the fact that the Universe itself even can be understood. It’s only because:

• nature itself obeys laws,
• those laws are universal,
• applying equally at all times and across all places,
• and those laws do not change or evolve, even if the conditions under which they operate do change,

that the very process of science for investigating reality gives us sensible answers. If this fact weren’t true, then everything we understand, as well as everything we can make predictions for and concoct after-the-fact explanations for, would be chaos. This, itself, is the most profound fact about existence, and what enables science to be possible at all. Here’s how.

Although human beings are made of cells, at a more fundamental level, we’re made of atoms. All told, there are close to ~10^28 atoms in a human body, mostly hydrogen by number but mostly oxygen and carbon by mass.

Think about whatever your favorite scientific fact is about the Universe: something that we’ve learned because we’ve observed, measured, or experimented on some aspect of reality. It could be something:

• physical, like the fact that our bodies, and everything around us, is composed of atoms,
• astrophysical, like the fact that the complex atoms that compose us were forged in ancient, exploded stars whose remnant material was incorporated into the primeval nebula that formed our Solar System,
• chemical, like the fact that it’s the breaking and reforging of bonds between atoms that power all organic and inorganic processes on Earth,
• biological, like the fact that the nucleic acids in our cells encode what types of proteins, enzymes, and structures a cell will produce,
• geological, like the facts of how rocks, minerals, or the interiors of planets are formed,
• or climatological, like the fact that our planet is 59 °F (33 °C) warmer than its equilibrium temperature would have been had we lacked an atmosphere,

to name just a few examples.

Each one of these facts was uncovered by humans who were observing facts about some aspect of the Universe, collecting and synthesizing data from a wide array of sources, investigating a few isolated aspects of reality and how those aspects related to one another, and involved a fusion of both the underlying theories of how the Universe worked with either experimental or observational data gathered while interrogating nature’s workings. We found these facts out about reality, quite simply, by taking what we already knew and established as our foundations and then putting the key question to the Universe itself.

This densely populated region of space is focused on galaxy cluster SDSS J1004+4112, and showcases several objects that appear multiply imaged owing to gravitational lensing. Once called a “five star” lens, the star-like appearances seen near the cluster’s center are actually the same quasar imaged five times in the same field-of-view: a deceptive trick of light and gravity.

That’s the basics of how science works. We always begin with some set of assumptions or postulates: a starting point that’s foundational for taking any next steps. We then use what we already know to make some sort of prediction or set some sort of expectation for what we expect to happen, given a certain physical, material system or set of conditions. Then, under as controlled of a set of conditions as we can muster, we observe and measure what actually does happen under the physical conditions that occur naturally in our real, material Universe. Finally, we put the full suite of information together that we’ve collected, both in this specific study and from all previous relevant studies, and synthesize it to draw whatever conclusions are best supported by the data.

This might not sound like the scientific method that you were taught, but it’s a more accurate encapsulation than the standard explanation where you:

• formulate a hypothesis,
• design an experiment to test the hypothesis,
• perform the experiment,
• perform your results,
• and then draw a conclusion where you either validate, refute, or refine your hypothesis.

The goal, after all, is not merely to formulate and test a hypothetical idea, but rather to gather more information about the world and Universe as it actually is than our best prior understanding had given us.

Planet Earth, as viewed by NASA’s Messenger spacecraft as it departed from our location, clearly shows the spheroidal nature of our planet. This is an observation that cannot be made from a single vantage point on our surface, but there are many valid ways to measure the curvature of the Earth, all leading to the same conclusion. There is no scientifically valid test that can be performed that supports a flat Earth over a round one, providing justification for the scientific consensus position concerning the shape of the Earth.

But why does this work? Why can we draw our conclusions based on not only what we learned today, from our current experiments and observations, but based on everything that was known, learned, measured, and observed previously?

Because of that one foundational, amazing fact that we so often take for granted: the fact that the Universe itself exists in such a way that it can be understood.

There are many ways that the Universe could have been different — as different as we dare to imagine — that would have prevented this fact from being true. For a few examples:

• The Universe could have had fundamental laws that weren’t constant: with forces that could appear and disappear, turning themselves on-or-off, or that varied wildly in strength from one moment to the next.
• The Universe could have exhibited glitches or instabilities: moments in time or regions of space where things didn’t obey the physical laws and rules we’ve worked so hard to sleuth out.
• The Universe could rely on forces or phenomena that were unpredictable and unobservable, as though there were some hidden, undetectable influencer of reality that existed outside of anything we could perceive or measure.
• Or the Universe could be logically inconsistent, where cleaving an object in two resulted in duplicating, rather than halving, the original object.

A fascinating class of organisms known as siphonophores is itself a collection of small animals working together to form a larger colonial organism. These lifeforms straddle the boundary between a multicellular organism and a colonial organism. Even though this collection of organisms may exhibit a complex set of emergent behaviors, the underlying laws that govern them remain unchanged from moment-to-moment and place-to-place.

If any of these hypotheticals wound up describing our Universe, we would be unable to make sense of it in the way we presently do.

Consider gravity, for example. Here on the surface of the Earth, we — and everything we interact with — reliably get accelerated downward, toward the center of the Earth, at the same rate that every observer on Earth measures: 9.8 m/s². We take for granted the fact that this acceleration is constant and consistent, applying all over the Earth and at all times, and never changes. In fact, it’s the same underlying law of gravity that holds the Earth itself together, that causes the Moon and other satellites in our vicinity to orbit the Earth, and that enables Earth and most bodies in our Solar System to revolve around the Sun.

But what if the force of gravity weren’t constant? What if, from one moment to the next, it varied in strength? What if it sometimes turned itself off before turning itself back on again? What if it reversed sign occasionally, causing us to accelerate upward instead of downward before returning to its normal value again? Or what if it behaved chaotically, varying in strength and causing us to alternately float, sink, rise, and slam into the ground?

In our conventional reality, the Earth stably orbits the Sun, which continues to shine and which remains as a relatively constant, only slightly-changing source of mass and gravity. However, if the law of gravity or the strength of the gravitational interaction changed dramatically, the Sun could easily collapse to a black hole and then destroy and tear apart the Earth. Only because the laws of nature are the same throughout time and across space can we be confident that tomorrow will indeed safely arrive.

Such a Universe, instead of being ordered, would be completely unpredictable. We couldn’t infer the location of where a grenade exploded, for example, simply by following the shrapnel and tracing each fragment back to the same point-of-origin, because each individual piece not only wouldn’t necessarily obey a consistent set of laws over time, but because each individual piece might be obeying different rules from every other piece.

In such a Universe, planets wouldn’t be able to remain in stable orbits around their parent stars, nor would the planets and stars themselves even be able to hold themselves together. Galaxies would dissociate when gravity either turned off or became negative, then violently reform when it turned back on at normal (or greater) strength. The future trajectories of objects would become wildly unpredictable, and the past trajectories of objects would not follow any sort of sensible rules; the chaotic nature of the rules that our physical system obeys would preclude us from drawing conclusions about what previously occurred based on what we can observe at present.

Without stable rules to play by, none of the other “amazing facts” about reality would be possible.

The quarks, antiquarks, and gluons of the Standard Model have a color charge, in addition to all the other properties like mass and electric charge. All of these particles, except gluons and photons, experience the weak interaction. Only the gluons and photons are massless; everyone else, even the neutrinos, have a non-zero rest mass.

The fundamental building blocks of nature — the elementary particles of the Standard Model — can only form the complex entities that they do:

• protons and neutrons,
• atomic nuclei,
• atoms,
• molecules,
• and human beings, among other composite structures,

because their individual properties (electric charge, rest mass, couplings, etc.) remain constant over time, and remain constant even between different particles of the same species. The strength of the forces that these particles experience might vary with their proximity to other sources of mass and charge, but the rules that they play by remain constant, with the resultant force being dependent on measurable, knowable physical properties.

These rules apply to all particles at all times; there are no sets of particles that experience these physical laws differently than any other sets of particles. The gravitational, electromagnetic, plus the weak and strong nuclear forces are the same wherever you go and whenever you look. The particles that exist have the same properties at all times and at all locations. The rules that govern the entire Universe are the same: on tiny, subatomic scales and on enormous, cosmic scales. All of what occurs within our Universe, at all energies, at all times, and in all places, obey the same fundamental, underlying laws.

The idea that two quanta could be instantaneously entangled with one another, even across large distances, is often talked about as the spookiest part of quantum physics. If reality were fundamentally deterministic and were governed by hidden variables, this spookiness could be removed. Unfortunately, attempts to do away with this type of quantum weirdness have all failed, as any experimental difference between the Copenhagen interpretation and hidden variable theories has only supported the standard picture of quantum mechanics.

On top of that — at least, as far as we can tell — the only laws and rules that influence everything that exists within our Universe are the physical forces and interactions between the physical, material entities that we can observe and measure within our Universe. There are no outside forces, no unmeasurable influences, no unobservable entities that cause unexplained phenomena to appear or unexplained behaviors to occur within this Universe: everything that we observe and measure can be explained within the context of physical, materialist reality. Although there are many who hold philosophical or religious beliefs to the contrary, there is no scientific evidence that supports such a position.

It is only on account of these facts, of the fact that our material reality obeys the same physical laws and rules from moment-to-moment and place-to-place, and that the same ingredients have identical properties at all locations and times, and that there are no unseen, unpredictable, outside influences that otherwise affect our material reality, that we can make sense of the Universe at all.

Any other fact that you might hold dear about reality itself is predicated on the foundation of these facts, and that’s what makes them the most amazing set of facts in the Universe. Without them, our ability to make sense of our Universe — and for science to work at all — would be stripped away.

When multiple masses interact under their own mutual gravitation, the smaller masses tend to get larger kicks, where they get knocked to higher orbits or ejected entirely, often resulting in hypervelocity objects. Meanwhile, the remaining objects wind up even more tightly bound, gravitationally speaking. If the law of gravity were not a constant, with a universal, unchanging strength and the same force law governing it always, scientifically accurate predictions and reconstructions for physical systems would be impossible.

Imagine what reality would be like if these facts weren’t true. Imagine existing within a Universe where nature behaved randomly, unpredictably, and chaotically. Where not just gravity but all of the forces could increase, decrease, turn on-and-off, or reverse sign instantly, with no decipherable rhyme or reason to why they did so. Where even if you managed to form a star, like our Sun, it could simply stop burning its fuel, or shining and emitting energy, with no discernible cause or mechanism that would explain how such a thing occurred. Even if you, a human, managed to come into existence, your constituent atoms could just as easily fly apart as they could continue to hold together.

Such a Universe, indeed, would truly be frightening: far more frightening than any phenomenon or cataclysm that could arise in our present-day Universe. At least, in our Universe, what occurs can be understood, and we can learn how to predict what’s going to happen in the future based on the conditions that are in place today. But in a Universe that didn’t obey consistent laws and rules, the things that you learn here-and-now might not be true at some later moment in time, and they might not even apply an arm’s length away from you. Such a Universe, one that didn’t obey consistent rules, could never be understood.

This chart of particles and interactions details how the particles of the Standard Model interact according to the three fundamental forces that quantum field theory describes. When gravity is added into the mix, we obtain the observable Universe that we see, with the laws, parameters, and constants that we know of governing it. However, many of the parameters that nature obeys cannot be predicted by theory, they must be measured to be known, and those are “constants” that our Universe requires, to the best of our knowledge.

Fortunately for us, our Universe is a place where the laws and rules apply universally: to all quanta at all times and in all places. While the matter and energy that exist within our Universe can change, they can only change based on a specific set of fundamental laws. While the spacetime that governs our Universe can change, it can only do so in the various ways that the laws governing it admit. Even though our Universe is not static and unchanging, the fundamental laws that it follows are constant, and do not change either with space or with time. The universality of the underlying laws and rules that govern reality is what allows us to understand and make sense of anything at all.

With this “most amazing fact” in place, we can indeed:

• observe the Universe,
• measure the Universe,
• experiment on the Universe,
• assemble and disassemble anything we find within the Universe,

and leverage the results that we find out from these endeavors and inquiries to construct a suite of information about the Universe that teaches us about its behavior and properties, both in part and as a whole. Only if the fundamental laws of the Universe are the same everywhere and at all times can we make sense of our physical reality, and yet, that’s exactly the Universe we appear to inhabit, as validated by what we find when we put nature itself to the critical test.

Without this “most amazing fact,” science itself would not be possible, and none of the scientific facts we enjoy and marvel at today would necessarily have been true yesterday, nor would they be guaranteed to be true tomorrow. The most amazing fact about the Universe, quite simply, is the fact that anything about it is able to be understood at all.