On a cold February morning in 1600, a man—stripped naked, tongue clamped—was led into the Campo de’ Fiori in Rome, to be burned alive. His crime was not murder, theft, or treason. His crime was believing that the universe was bigger than the Church allowed.
The man was the Italian philosopher Giordano Bruno, executed for the sin of taking seriously the emerging science of heliocentric (Sun-centered) astronomy—and pursuing its full theological implications. This led Bruno to reject the teachings of Catholic orthodoxy—including the virgin birth and divinity of Christ—and it was this, ultimately, that spelled Bruno’s untimely death.
In remembrance of the great Italian philosopher, we’ll explore the ideas that led Bruno to challenge the orthodoxy of his time—and to ignite the imagination of future scientists who refused to allow the authority of scripture to constrain their expanding vision of the cosmos.
Giordano Bruno (1548 – 1600) was born in Nola, a small town in the province of Naples. He was later sent to Naples to be educated, eventually being ordained as a Catholic priest. After years of studying, thinking, and teaching across the great academic and cultural centers of Europe, Bruno eventually developed views far outside the bounds of religious orthodoxy, resulting in his eventual conviction as a heretic after an eight year “trial” conducted by the Roman Inquisition. He was sentenced to death by burning at the stake.
The question is: Why did the Church feel so threatened by this otherwise peaceful man? It turns out that, at least in one sense, the Church was right to be worried—Bruno’s vision put an end to scriptural authority in science.
At the heart of Bruno’s vision are two bold and revolutionary claims—with explosive implications. First, that the Earth is not the center of the cosmos (nor is anything else), and second, that the universe—and space itself—is infinite.
Regarding his first claim, Bruno could rely on the authority of Nicolaus Copernicus, who, in 1543, published his paradigm-shifting On the Revolutions of the Celestial Spheres, establishing the heliocentric model. But Bruno went further: he recognized that simply replacing the Earth with the Sun as the universe’s center reproduces the same fundamental error as geocentrism. Heliocentrism, taken this way, still misrepresents the true nature and vast scale of the cosmos.
“For the universe has no center, no circumference,” Bruno wrote in On the Infinite Universe and Worlds. “Rather, if you will, everything is in the middle, and every point can be taken as a point of the circumference with respect to every other middle or center.”
To Bruno, there is no universal center, only relative positions compared with other astronomical bodies (anticipating later ideas about the relativity of position and motion). In examining the night sky, Bruno saw what orthodox believers could not: that the thousands of visible stars were other suns, the same as our own, with their own orbiting planets that, to Bruno, were almost certainly teeming with life. Bruno thought that “planets rotate around those other stars, and are composed of the same material as ours is, and should therefore be able to sustain life.”
More than 400 years before the astronomer Carl Sagan launched the Golden Record into space on the Voyager spacecraft—designed to communicate the story of Earth to any intelligent extraterrestrial life that might find it—Bruno hypothesized the existence of alien life based on the infinite uniformity of space. This remarkable insight anticipates what many living physicists, to this day, believe to be true (see the SETI project).
As to his second claim, Bruno asserts that “the universe is infinite and has no limit or boundary.” To support this, he quotes Lucretius:
Of course, if you have set up an end to all of space, and if anyone ran its course to the furthest shore, and shot an arrow however weakly or strongly, which do you think would happen? That there would be some obstruction which would prohibit further flight, or that nothing would stop it, so that it continues on the path it was sent, but wherever it ends up, no doubt this is not the end either.
How, Bruno would ask, can there be an “end” to space? Imagine traveling to this boundary and describing what you see. If, in the first place, you find that something exists beyond the boundary, then there is something there, and the universe is therefore not finite, but extensible. On the other hand, if “nothing” lies outside the boundary of the universe, then the boundary itself becomes incoherent, because a border implies the separation of two distinct, actually existing things. And if something cannot be said to border on nothing—in other words, that something must exist on the other side—then, again, the universe cannot be finite, but infinitely extensible.
“Were one to stand at the edge of the world and extend one’s hand outside the convexity of it, then that hand would have no position nor location, and so would cease to exist,” one of Bruno’s interlocutors is made to say. Surely, this claim is more incoherent than the simple infinite continuation of space. And if space is infinite, the theological implications are impossible to ignore.
In Bruno’s mind, placing limits on the universe places limits on God; an infinitely powerful being would create an infinity of worlds, and, since the same laws of physics apply to every corner of the cosmos—and no particular spot is privileged over any other—then the universe must be filled with an infinite number of similar worlds—worlds that must be supportive of life.
This expanded domain for an infinitely powerful God might have been eagerly embraced by the Church. Unfortunately, their hands were tied. Scripture conclusively said otherwise—stubbornly insisting on a geocentric model that would force Galileo to recant his heliocentrism a few decades later.
But Bruno, unlike Galileo, would not recant—so he was burned alive while Galileo was spared. Yet what both of them surely realized was that the real problem was not the peaceful speculations of philosophers and scientists—but the tyranny of scriptural authority in science itself.
Those familiar with scripture need not look hard to find support for the Earth’s preeminent position in the cosmos. “[God] set the earth on its foundations; it can never be moved” (Psalm 104:5). “The world is firmly established, it cannot be moved” (Psalm 96:10). “Tremble before him, all the earth; yes, the world is established; it shall never be moved” (1 Chronicles 16:30).
We get the point: the Earth is clearly not meant to be moved. And if that’s the case, then it follows that the Sun must move, as we witness it sweep across the sky each day. The Bible, indeed, confirms this:
On the day the Lord gave the Amorites over to Israel, Joshua said to the Lord in the presence of Israel: “Sun, stand still over Gibeon, and you, moon, over the Valley of Aijalon.” So the sun stood still, and the moon stopped, till the nation avenged itself on its enemies, as it is written in the Book of Jashar. The sun stopped in the middle of the sky and delayed going down about a full day (Josh. 10:12–13).
The Sun cannot be stopped if it doesn’t move, and so the Bible establishes the motion of the Sun twice over: first, in relation to a motionless Earth, and second, in consequence of a miracle that stops the Sun dead in its tracks.
In addition, Holy Scripture paints the universe as rather small and bounded. Consider Psalm 19:4-6:
In the heavens God has pitched a tent for the sun. It is like a bridegroom coming out of his chamber, like a champion rejoicing to run his course. It rises at one end of the heavens and makes its circuit to the other; nothing is deprived of its warmth.
No wonder Bruno and Galileo were so intensely investigated. Scripture is quite clear: the Earth is the central, stationary focal point around which the clockwork universe revolves, and the Sun, which traverses the full span of the heavens, furnishes us with its all-encompassing warming embrace. God, transcendentally standing outside of this majestic operation, sets the Sun in motion and supervises the laws of nature, bending them, when necessary, at His will and pleasure.
This view of the cosmos—which places God outside of the operation of the laws of physics—is ripe for the establishment of implausible ideas, because it disconnects God’s actions from any and all physical constraints. Consequently, virgins can now freely give birth (the Annunciation), the dead can spontaneously arise (Jesus’s Resurrection), God can be one and three at the same time (The Holy Trinity), and bread and wine can become flesh and blood (Transubstantiation).
Bruno rejected all of this on the grounds that, if the Bible is wrong about the basic mechanics of the cosmos, then its supernatural claims could no longer be unquestioningly accepted. After all, scripture cannot be the divinely inspired word of a creator who doesn’t even understand his own creation!
Scripture, then, clearly misrepresents the nature of the cosmos. But was Bruno right? Is the universe actually infinite?
The honest answer is, we don’t know. At the heart of the problem is that we are limited by what we can see—the observable universe—which is about 93 billion light-years across, a finite size. But this is only what we can observe; as to what lies beyond—the unobservable part—we are blind. It could, in theory, extend forever, but right now, we have no means of accessing it.
In any case, the geometrically flat curvature of space suggests that it is either infinite or incomprehensibly large—containing roughly two trillion galaxies—which, if not quite fully vindicating Bruno, in practical terms, amounts to the same. 93 billion light-years across is a lot closer to infinity than a universe in which one medium-sized star can travel its diameter in a day.
No matter how hard you try, you can never quite appreciate just how large the universe is. Light travels fast—more than 670 million mph—and takes just over 8 minutes to reach the Earth from the Sun. Yet it would take light 93 billion years to cross the entirety of observable space. These kinds of distances are not even remotely fathomable.
So while we cannot say with certainty that the universe is infinite or teeming with life, the possibility now seems not only plausible but almost inevitable. And it was Giordano Bruno—standing alone against the intellectual authority of his age—who first dared to imagine such a cosmos. For that vision he was burned alive, but history has rendered its verdict: the universe he glimpsed in imagination turned out to be far closer to reality than the cramped and parochial cosmos of his judges. In that sense, Bruno stands as one of the earliest martyrs for science, freethought, and humanity’s expanding understanding of its place in the universe.
References
Bruno, Giordano. On the Infinite, the Universe and the Worlds: Five Cosmological Dialogues. Translated by Scott Gosnell. CreateSpace Independent Publishing Platform, 2014.
National Aeronautics and Space Administration (NASA). “Stars — Explore the Universe.” NASA Science. Accessed February 13, 2026, https://science.nasa.gov/universe/stars/.
SETI Institute. “Home.” Accessed February 17, 2026, https://www.seti.org/.
Siegel, Ethan. “Is the Universe Infinite?” Big Think, Starts With a Bang. Accessed March 5, 2026. https://bigthink.com/starts-with-a-bang/universe-infinite/.