Are the laws of Physics the same outside the observable universe?

Q: How are we sure that the laws of Physics are the same outside the observable universe?

Krishna: 

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Physicists usually say this:  The laws of physics are the same throughout the universe. If we found out that a certain law didn't apply in a certain situation, we'd be very curious why, and we'd work hard to find out the reasons and modify the law(s) until they were once again universal.  The assumption that the laws of physics are the same outside the observable universe is based on several scientific principles and observations: Consistency in Observations: The laws of physics are consistent across the universe, as evidenced by the uniformity of the universe's structure and behaviour, such as the expansion of space and the distribution of galaxies.  Fine Structure Constant: The fine structure constant (α), which governs the interaction of light and matter, has been measured to be the same in all directions and at all distances, indicating a universal law.  Galaxy Clusters: The pattern of galaxy clusters in the universe is consistent, suggesting that the laws of physics are consistent throughout the universe.  Gravitational Lenses: The bending of light by massive objects, such as galaxies, stars, and black holes, is a consistent phenomenon that occurs in all parts of the universe.  Theoretical Consistency: Theoretical models of the universe, such as the Big Bang theory and the theory of general relativity, predict the same universal laws of physics.  These observations and theoretical predictions provide strong evidence that the laws of physics are consistent and universal across the universe. 

However, the laws of physics describe the behaviour of matter, energy, space, and time.

These include well-known principles such as: Newton’s Laws of Motion, Einstein’s Theory of Relativity The Laws of Thermodynamics, The Standard Model of Particle Physics. These laws are incredibly consistent here on Earth and within our observable universe.

But that raises the question — have we just been lucky to observe one kind of physical reality? Could different “cosmic neighbourhoods” play by entirely different rules?

What Would It Mean for the Laws of Physics to Be Different? If the laws of physics varied elsewhere, it could mean:

Different values for fundamental constants (like the speed of light or gravitational constant)

Altered behavior of particles and forces

The existence of universes where atoms, stars, or even life as we know it could not form

It would be a profound shift in our understanding of reality.

And scientists aren’t just speculating — some evidence suggests this idea might not be as far-fetched as it seems. Could the laws of physics be different in other parts of the universe? 

Observational Clues from Deep Space

 Variations in the Fine-Structure Constant? The fine-structure constant (α) governs how strongly light interacts with matter. It is a dimensionless number around 1/137. However, in 2010, a study of light from distant quasars suggested slight variations in α over vast cosmic distances (1). If true, this could mean the laws of physics are not fixed.  

Dark Energy and the Expanding Universe: The accelerated expansion of the universe, attributed to dark energy, is another mystery. Scientists still don’t fully understand it — and if dark energy behaves differently across space, that could imply variations in gravitational or quantum physics.

 Theoretical Foundations for Variable Physics - Multiverse Theory:

The multiverse hypothesis suggests there may be infinite universes, each with different physical constants and laws. In some, gravity might be stronger; in others, electromagnetism might not even exist. This concept arises naturally from inflationary cosmology and string theory. In such a scenario, our universe would just be one “bubble” in a vast cosmic foam, each governed by its own laws of physics.  

String Theory and Extra Dimensions: String theory attempts to unify quantum mechanics and general relativity by proposing that fundamental particles are one-dimensional “strings” vibrating at different frequencies. The mathematics of string theory allow for a wide range of possible physical laws, depending on how the extra dimensions are “curled up.”  

Could Life Exist with Different Laws? It’s hard to say. If the constants that govern nuclear fusion or chemistry were only slightly different, stars might never form, or DNA might not function. But we can’t rule out completely alien forms of matter or life that could thrive under unfamiliar laws.

Some researchers speculate about “anthropic selection” — we observe our set of physical laws because only those allow conscious observers to arise in the first place.

 Experimental Frontiers and the Future: We’re limited by the observable universe, but as our telescopes and technologies improve, we may uncover more clues. James Webb Space Telescope is examining the earliest galaxies for signs of different cosmic conditions. Gravitational wave detectors might uncover phenomena that hint at extra dimensions or exotic physics. Particle accelerators like the Large Hadron Collider test the boundaries of known physics on Earth. (5)

So, a Universe of other Possibilities can still be considered and that exploring whether the laws of physics vary across the cosmos is not just an academic exercise — it’s a journey to understand our place in the universe. While the idea may seem speculative, real observational and theoretical frameworks continue to explore the possibility. If the laws of physics do change in other regions of space or in parallel universes, it would redefine everything we think we know about reality. For now, we live in a universe where physics appears stable — but the cosmos is vast, and full of surprises.

We are still investigating, and the work is in progress is all we can say now!