Ask a physicist "where does time begin" and you'll likely get a long, slightly frustrated sigh before they start drawing circles in the air. It’s not a simple question. Most of us grew up with this mental image of a cosmic starter pistol—a "Big Bang" that just pop and suddenly there’s a clock ticking. But the truth is way weirder. It’s more like a blurry smudge where the rules of the game didn't exist yet.
If you’re looking for a GPS coordinate or a specific date on a calendar, you’re going to be disappointed. Time doesn't have a "Made in China" sticker on the back of it. Instead, we have to look at the very limits of what math can actually tell us about the universe.
The T=0 Problem
Most people assume where does time begin is a point called $t = 0$. In our standard cosmological models, we trace the expansion of the universe backward. Everything gets smaller. Everything gets hotter. Eventually, you hit a point where all the matter in the universe is packed into a space smaller than an atom.
This is the Singularity.
But here is the catch: the math breaks. Stephen Hawking famously compared asking what happened before the Big Bang to asking what is north of the North Pole. It’s not that there’s a secret "Forbidden North." It’s that the geometry of the Earth makes the question meaningless. In the same way, the geometry of spacetime might just curve back on itself at the very start.
If you talk to someone like Dr. Thomas Hertog, who worked closely with Hawking on his final theories, they’ll tell you that time didn't just "start" like a light switch. It likely emerged. It evolved. In those earliest moments, there wasn't even a distinction between space and time. It was all just a high-energy soup where the dimensions hadn't frozen out yet.
When the Clock Actually Started Ticking
We can't see the "beginning." We can only see the leftovers.
The furthest back we can actually "see" with light is the Cosmic Microwave Background (CMB), which happened about 380,000 years after the Big Bang. That’s a long time to wait for a photo. To get closer to the answer of where does time begin, scientists have to use particle accelerators like the Large Hadron Collider (LHC).
By smashing protons together, we recreate the energy densities that existed just fractions of a second after the start. We’re talking $10^{-12}$ seconds. That’s a decimal point followed by eleven zeros and a one. At that point, time was definitely happening. Particles had mass. Forces were starting to separate.
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But go back further to the Planck Epoch ($10^{-43}$ seconds). This is the "wall" of physics. At this scale, our understanding of gravity (General Relativity) and our understanding of the small stuff (Quantum Mechanics) start screaming at each other. They don't match. This is why we don't have a definitive answer for the absolute origin. Without a "Theory of Everything," the "where" and "when" of time’s origin remains a mathematical ghost.
Is Time Just an Illusion?
There is a growing camp of physicists, including folks like Carlo Rovelli, who argue that time isn't even fundamental.
Think about a temperature. "Hot" isn't a fundamental thing. It's just a way we describe a bunch of molecules moving really fast. If you look at a single atom, "temperature" doesn't exist. Some think time is the same way. It's an "emergent property."
In this view, the question of where does time begin is kind of like asking where a circle begins. It doesn't. We just experience it as a sequence because we are trapped inside the system. Our brains are built to perceive cause and effect, so we need a beginning. The universe might not be so needy.
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The Greenwich Mean Time Distraction
Whenever you search for where time starts, you'll inevitably see results for Greenwich, London.
Let's clear that up. That’s just humans being organized. In 1884, a bunch of guys in suits decided the Prime Meridian would sit at 0° longitude in Greenwich. This is where "clock time" or GMT (now UTC) is referenced. It has absolutely nothing to do with the birth of the universe. It’s a convenient fiction so we don't miss our flights.
The real "Time 0" isn't in London. It’s scattered across the entire fabric of the cosmos. Because the Big Bang happened everywhere at once, time began everywhere simultaneously. You are currently sitting at the site of the beginning of time. So am I.
Why This Actually Matters for You
It feels like high-level navel-gazing, but understanding the origin of time changes how we build technology.
- GPS Accuracy: Your phone relies on Relativity. Satellites move fast and are further from Earth’s gravity, so their clocks tick differently than yours. If we didn't understand how time warps, your Uber would be miles off.
- Quantum Computing: We are trying to build computers that operate on the edge of reality. To do that, we have to understand how time behaves at the quantum level, where it starts to get "fuzzy."
- The Fate of the Universe: If we know how time started, we can predict how it ends. Will it just stop? Will it reverse? (The "Big Crunch"). Or will it just keep stretching until time itself becomes meaningless again?
Honestly, the most humbling part is realizing we are living in the "Golden Age" of time. The universe is old enough to have formed stars and planets, but young enough that we can still see the glowing embers of the start. Trillions of years from now, the expansion of the universe will be so fast that other galaxies will disappear from view. Future astronomers (if there are any) won't be able to see the evidence of the beginning at all. They’ll think they are alone in a static void.
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We get to see the receipts.
Practical Ways to "See" the Beginning of Time
You don't need a PhD to touch the origin of the universe.
- Check the Static: If you have an old analog TV, about 1% of the "snow" or static you see between channels is actually interference from the Cosmic Microwave Background. You are literally watching the afterglow of the beginning of time.
- Look Up: When you look at the Andromeda Galaxy, you aren't seeing it as it is now. You're seeing it 2.5 million years ago. Telescopes are time machines. The further we look, the closer we get to the "Where."
- Download a Star Map: Use apps like Stellarium to track the movement of the heavens. It helps ground the abstract math into something you can actually see moving above your house.
To really wrap your head around this, stop thinking of time as a straight line. Think of it as a fabric that was folded up tight and is now unfolding. We are just ripples in that fabric. The search for the beginning isn't over—we're still waiting for the Webb Telescope and future gravity-wave detectors to give us a clearer picture of that first trillionth of a trillionth of a second.
Until then, just know that time didn't start in a place. It started as a change in the state of everything, all at once, for no reason we've quite figured out yet.
Next Steps for the Curious
Go to the NASA James Webb Space Telescope gallery. Look for the "Deep Field" images. These are the oldest objects ever recorded. When you look at those tiny red dots, you are looking at light that has been traveling toward you since shortly after time began. It's the closest thing to a "beginning" that our eyes will ever see.