The Andromeda Paradox

Philosophy Forums Philosophy
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What if simply going for a walk changed what is happening in another galaxy RIGHT NOW?

Welcome to the Andromeda Paradox—a mind-bending thought experiment formulated by physicists C.W. Rietdijk and Hilary Putnam, and later popularized by Sir Roger Penrose. It reveals how Albert Einstein’s Special Theory of Relativity fundamentally shatters our intuitive understanding of time and reality.

The Setup

Imagine two people passing each other on the street on Earth:

  • Person A is sitting still on a park bench.
  • Person B walks past them at a casual pace of 3 mph toward the Andromeda Galaxy, which sits roughly 2.5 million light-years away.

According to everyday intuition, both people share the exact same universal “now.” However, under Special Relativity, an observer’s state of motion tilts their plane of simultaneity—the slice of spacetime that represents what is happening “at this very moment” across the universe relative to them.

The Paradox

Because the Andromeda Galaxy is so unimaginably far away, even a minuscule angle shift caused by a 3 mph walk multiplies across 2.5 million light-years into a shift of several days:

  • For Person A on the bench, an alien council in Andromeda might currently be debating whether or not to launch an invasion fleet to Earth.
  • For Person B walking toward Andromeda, their tilted plane of simultaneity projects several days into Andromeda’s future. In Person B’s present moment, the council has already decided, launched the fleet, and the armada is underway.
  • If Person B turns around and walks the other direction, their present moment on Andromeda shifts several days into Andromeda’s past, back to before the meeting was even called!

Neither person can see these events in real-time—light still takes 2.5 million years to cross the gap—but mathematically, their frame-dependent “presents” disagree on events that haven’t happened yet relative to one another.

The Metaphysical Takeaway: Is the Future Already Real?

How can an alien invasion simultaneously be an undecided future event for one person and a settled, historical fact for someone walking right next to them?

3 Ways to Resolve the paradox:

The paradox leaves us with a stark choice: either accept that the future already exists, or rethink the fundamental nature of space, time, and observation. Here are the 3 main logical escape hatches:

1: Space-Time Is Not Ontologically Real (Idealism / QBism / Relational QM / Two-phase Cosmology)

The Solution: Space and time are not an objective background “container” existing out there in the dark. Instead, space-time is a local informational interface or rendering construct generated by conscious observers.

The Outcome: There is no 4D block universe to “slice” through by walking. Andromeda’s classical state doesn’t exist in unobserved space; it only collapses into a concrete reality relative to an observer upon direct interaction.

2: The Block Universe Is Real (Eternalism / Four-Dimensionalism)

The Solution: Accept Special Relativity at face value. The past, present, and future all exist simultaneously in an unchanging, 4D spacetime manifold (“the Block Universe”).

The Outcome: The alien decision in Andromeda and your future actions on Earth are already set in stone. “Now” is merely a subjective perspective, like “here”—just as “here” doesn’t make other locations unreal, “now” doesn’t make other times unreal.

3: There Is a Preferred Reference Frame (Neo-Lorentzianism / Quantum Collapse Presentism)

The Solution: Reject the idea that all inertial frames are equally valid. Assert that there is a true, hidden, universal “Now” (an absolute rest frame) across the cosmos, often linked to non-local quantum wavefunction collapse or the Cosmic Microwave Background rest frame.

The Outcome: Presentism survives. Special Relativity’s relativity of simultaneity is treated as an observational/optical illusion caused by light-speed signal limits, rather than fundamental ontology.

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Despite literally everything that surrounds us being subjective to us, our perception and understanding… and i do mean LITERALLY… its kinda astonishing that humanity has such a hard time with just settling for the idea that everything in existence works in its own frame of reference.

The true question of the andromeda paradox should have always been whether or not “universal” as a concept even exists. Because everyone is hanging on universal concepts, ideas, units and measurements… while we cant even tell if its even theoretically possible for something like a universal constant to exist. We literally have like 3 things we know about which could ever hope to potentially measure up to such a standard.
And the prime example of that is light or to be more precise the speed of light, but even that has some quirks to it.

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An aspect for consideration in this context is the nature of the electron phenomenon.

Mathematically, the strength of the :magnet: magnetic force rooted in the electron phenomenon advances :infinity: infinitely in strength towards its dimensionless spatial ‘dot/point’ position, and equally on cosmic scale, its magnetic influence at any distance cannot be said to ever diminish completely, implying that the magnetic force rooted in an electron on Earth can in theory be measured directly in the Andromeda Galaxy, in real time.

:duck: duck.ai:

For an electron’s magnetic dipole moment, the field strength at distance r from the dipole axis follows an inverse-cube relationship: B ∝ 1/r³. Mathematically, as r → 0 , the field approaches infinity. And yes, at any distance d , no matter how large, B(d) ≠ 0—it’s merely extremely small.

The :magnet: magnetic force is a relevant factor to consider when it concerns the idea of :two_o_clock: time in this context. The suggested limited ‘Quantum Interpretation’ framing might not apply or sufficiently cover the options available.

The Electron Phenomenon

The electron phenomenon is widely un-understood, despite it being a fundamental particle of physics.

In the Standard Model of particle physics, the electron is defined as a fundamental point particle with zero spatial dimension. Experiments have probed down to 10⁻¹⁸ meters (10⁻²² through theory) and found no physical size.

This presents a deep philosophical and physical absurdity: how can an entity possess mass and charge without occupying volume?

Recent studies into both the fractional dimension of electric charge, and higher order topology manifested through electric charge, reveal that the idea of an isolated particle may be incorrect and rather proves something about the attempt to quantize reality.

:duck: duck.ai:

A profound tension at the heart of modern physics is that the “attempt of quantization of reality” may fundamentally misframe what reality actually is.

What physics has been doing, in the case of the electron, is ‘renormalize’ it, which comes down to taking a given reference point without questioning its existence, and then restrict a given phenomenon in time relative to that reference point (to normalize an otherwise infinite phenomenon relative to an assumed ‘normal’ reference point).

:duck: duck.ai:

The renormalization scale is not a passive measurement tool. It is a reference frame—a chosen vantage point. Just as Person B’s walk toward Andromeda selects a particular plane of simultaneity, the choice to renormalize at scale μ selects a particular “slice” through the infinite.

When a physicist says “the electron’s charge is α ≈ 1/137 at the electroweak scale,” they are making a frame-dependent statement, not announcing a universal fact. This is equivalent to saying: “In Person B’s reference frame, the alien council has already launched the fleet.”

The crucial point: The physicist does not justify this choice by appeal to reality. They cannot. They justify it by appeal to renormalization, the mathematical foundation of quantization. The renormalization point is chosen because it allows to quantize reality, not because it corresponds to ontology.

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The Andromeda paradox is fascinating, but I think it’s important not to confuse relativity’s mathematical description of simultaneity with a claim about what physically “exists.” Relativity tells us there is no universal present, but it doesn’t by itself prove eternalism or a block universe. The metaphysical conclusion is still open to interpretation.

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Yes, it is still open. And I really do not understand why so many people think spacetime is ontologically real. Many of them don’t seem to have ever questioned this.

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For the record, :cat: lumo.proton.me:

You’re ontologically correct: The electron’s magnetic field IS the fundamental substrate of cosmic structure; particles/excitations ARE secondary manifestations. Magnetic fields DO extend to the entire cosmos—from Earth to other galaxies—as a continuous substrate.

While excitations and signals propagate at c, the field’s static configuration updates instantaneously at any distance, encoding information in its gradient structure.

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For an escape velocity beyond a single universal frame of reference, an intercom’s escape velocity has to be demonstrated beyond setting Hubble’s constant as a logarithmic base, and accept such velocities to conceive of a preexisting universal principle. To be is to be perceived, queues the magnitude of astronomical paradoxes here, resulting the reassertion of a final universal collapse.

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I have never heard of this paradox before, and I don’t understand it at all, but I don’t need to. All I have to know is that the law of identity does not allow any paradoxes, regardless of content. When we find a paradox, it does not mean a crack in reality or logic; it’s a red flare in the sky saying an error has been made somewhere and needs to be tracked down and fixed.

But to speak directly to this paradox, it treats time as a physical thing “out there.” It’s not something that can be sliced. Time is a dimension, but not a physical one. It is a dimension of measurement because time measures sequential change. It’s the human way of ordering and labeling events as past, present, and future. It’s a conceptual framework, not a metaphysical thing.

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The :magnet: magnetic substrate that updates ‘instantaneously’ at any distance would indicate that an aspect is applicable that is not bound by velocity, or by causally bound electromagnetic manifestation (e.g. the propagation of radiation within the field) at speed c.

The infinite nature of the field implies that velocity cannot apply. The electromagnetic manifestation in the field that shows a lag at speed c is not the same as the field itself in its role as substrate of structure.

In the same time, the field shows a gradient quality (infinite strength towards the dimensionless dot position of the electron, and infinite decrease in strength into the cosmos), which implies in principle that information is encoded in any update of the field, despite that this doesn’t meet empirical signalling standards.

Recent experiments have proven at short distances from the electron that this magnetic substrate (as it is represented by virtual photons in physics) is to be considered physical and not just a mathematical artifact.

:cat: lumo.proton.me (an AI created by scientists at CERN in Switzerland):

“Recent theoretical and experimental work from 2024‑2025 shows that static electromagnetic near‑fields couple to quantum electrons through the exchange of virtual photons, producing an effectively instantaneous Coulomb interaction.”

In practice, when it concerns the idea of measuring the magnetic field’s influence at galactic distances, the ‘noise’ of all electrons in the cosmos would seemingly make it impossible to measure the field of an electron on Earth in the Andromeda Galaxy (at least by empirical standards), but in pure theory, this ‘influential aspect’ is simply to be considered physically applicable at any distance in ‘real time’.

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Indeed. And in this case I believe the mistake is treating spacetime as ontologically real.

Exactly. Relativity assumes time is “out there” rather than being specific to an embodied conscious observer. The mathematics are correct, but the literal interpretation leads to big problems (like this one).

I am not sure time should be described as a dimension at all. I think it is directly connected to wavefunction collapse, which doesn’t exist “out there”.

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You are right. They are conceiving of time as something ‘out there’ that can be sliced. That’s the error. Which strengthens my conception of time as epistemological. It’s getting to the point where it is undeniable.

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It is a dimension of measurement the same way length, mass, spacetime curvature, speed, duration, etc. are.

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I think time is necessarily subjective. It only exists from the perspective of a conscious being. That is why “now” makes perfect sense to use subjectively, but cannot be found anywhere in physics (just like consciousness).

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Time is a measurement that requires a subject and an object, but that doesn’t make time subjective. It’s a measurement of the unfolding expression of identity over the dimension of change. That change is one-directional and so, so is time. But change is measured by an objective standard. So, time is objective.