The Cosmic Equation

"Somewhere, something incredible is waiting to be known." - Carl Sagan A blog exploring the deepest questions in physics, cosmology, and philosophy. Blog link: https://thecosmicequation.com

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“I don’t know what I may seem to the world, but as to myself, I seem to have been only like a boy playing on the sea-shore and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.” — Sir Isaac Newton

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“Aristotle said a bunch of stuff that was wrong. Galileo and Newton fixed things up. Then Einstein broke everything again. Now we’ve basically got it all worked out, except for small stuff, big stuff, hot stuff, cold stuff, fast stuff, heavy stuff, dark stuff, turbulence, and the concept of time.” — Zach Weinersmith, Science: Abridged beyond the Point of Usefulness

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Could Time Travel Be Possible?

Is time travel really impossible? Einstein’s equations suggest otherwise.

When Einstein united space and time into a single fabric, spacetime, he changed the way we see the universe. In relativity, time is woven into space itself, and it can bend, warp, or even loop back.

A wormhole is one possible “shortcut” through spacetime, a tunnel connecting two points. If one mouth moves at near light-speed and returns, relativity says time passes differently at each end. In theory, that’s a time machine.

Physicist Frank Tipler proposed another idea: an infinitely long, rapidly rotating cylinder. If you spin it fast enoguh, spacetime could curve into closed loops, letting you travel into your own past.

But even if we could travel back, the universe might resist. Consider the Grandfather Paradox, for example - if you went back in time and killed your own grandfather before he had children, then you couldn’t have been born, but then you couldn’t have killed your grandfather.

Stephen Hawking proposed the “chronology protection conjecture” to get around this.

Maybe time travel isn’t “forbidden”, but just self-correcting.

Read more on the topic here: https://thecosmicequation.com/time-travel-might-be-possible-according-to-physics/

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“Physics is really nothing more than a search for ultimate simplicity, but all we have is a kind of elegant messiness.” - Bill Bryson, A Short History of Nearly Everything

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Time Travel Might Be Possible, According to Physics

https://thecosmicequation.com/time-travel-might-be-possible-according-to-physics/

Time travel has always seemed far-fetched and unrealistic, belonging to the world of sci-fi books and Hollywood blockbusters like Back to the Future and Interstellar. While real time travel might not be as spectacular or fantastical as these portrayals, physics suggests that it might not be entirely out of reach.

We’re all time travellers in some sense, constantly hurtling forward through time at a rate of one second per second. But could we ever travel faster, or even backwards, through time?

Could time travel ever become a reality?

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The Theory of Everything: Can One Equation Explain the Universe?

https://thecosmicequation.com/the-theory-of-everything-can-one-equation-explain-the-universe/

For thousands of years, humans have wondered whether the universe follows a deeper order. Ancient Greek philosophers like Pythagoras and Plato believed that a unifying, rational principle governs all of reality and organises the cosmos.

In modern physics, this idea takes the form of a “Theory of Everything” (TOE): a hypothetical framework that would unify all fundamental forces and particles into a single, elegant mathematical system that could explain both the vastness of galaxies and the tiniest subatomic particles. Great minds like Albert Einstein and Stephen Hawking devoted their lives to this pursuit, but so far, the ultimate theory remains elusive. This raises a tantalizing question: does such a theory even exist?

If discovered, a theory of everything could help us answer some of the deepest mysteries of the universe: what happened before the Big Bang, what lies beyond a black hole, and whether our universe is actually a part of multiverse containing many other parallel universes.

In this post, I’ll explore what we already know, the leading candidates for a theory of everything, and whether a unified framework of the cosmos is even possible.

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“Not only is the Universe stranger than we think, it is stranger than we can think.” - Werner Heisenberg

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The Big Bang: A Beginner’s Guide to the Start of the Universe

https://thecosmicequation.com/the-big-bang-a-beginners-guide-to-the-start-of-the-universe/

Every story has a beginning. Let me tell you the story of our universe.

Once upon a time… there was nothing. Absolutely nothing. But not the kind of nothing we can imagine—not empty space or a dark void. There was no space at all. And yet, in that unfathomable absence, there existed an impossibly small, unimaginably dense point containing everything.

Then, it began to expand, not into space, but as space itself. This moment marks what we have now come to understand as the beginning of the universe.

What I’ve just described is, scientifically speaking, known as the Big Bang theory. This has come to be one of the most important ideas in modern physics—a model explaining the evolution of our universe from a hot, dense state into the vast cosmos we see today. Not only that, it serves as the foundation of cosmology, influencing our understanding of matter and time itself.

At its heart, the Big Bang theory says that around 13.8 billion years ago, the universe began as a singularity, i.e. an infinitely small and dense point, which then rapidly expanded. This wasn’t an explosion in space; it was the expansion of state itself.

As the universe grew, it cooled. Energy condensed into particles, which formed atoms, and then stars and galaxies—and, eventually, planets, life, and minds curious enough to ask: How did it all begin?

In this post, we’ll explore what the Big Bang theory really says, the evidence supporting it, and the key milestones in the early life of our universe...