Bootstrap Paradox: We all know Albert Einstein, Isaac Newton, Erwin Schröndinger, and maybe even more so, we know their legacy, what they left us and the world. So let us imagine that we were able to travel back in time to meet these geniuses, maybe ask them about their work, exchange a few words or two about their recent breakthroughs, but as we arrive, the name Einstein is unknown all, non-existent.

Having brought from the future the memories of Einstein’s work and their specificities, a man who now does not exist, we start to publish it ourselves, feeding our future selves the reason we came back to the past in the first place. Therefore, it appears that we are stuck in an endless causal loop: the works of these scientists caused us to go back in the past, yet we are what created them. And here, we have a paradox, the bootstrap paradox.

At the core of the paradox

Bootstrap Paradox
An illustration of the Bootstrap Paradox

In one sentence, the bootstrap paradox distorts our understanding of cause and effect. Let us set up a linear timeline of events A (we hit a pool ball numbered 1), B (1 hits another ball numbered 5), and C (5 hits the next ball numbered 6 and 6 goes on), where time passes in a straight line from A to C, from the past to the present, and then the future, each event consecutively causing the next as shown above. A causing B, B causing C. In this “normal” and logical case, concordant with how we understand our world, the future is uncertain and dependent on our actions in the past and present.

However, when a time traveler is introduced and brings information from C to influence or cause A (6 hits 1), this chain of casually interlinked events is distorted. In short, the bootstrap paradox exists where C causes A, where information, people, or objects from the future cause the past.

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Implications of the paradox

Indeed, the implication of this breach in the causality loop is heavy. First, it implies that to fit with our linear understanding of time, the future event C has already happened at event A. This is thoroughly inconsistent. Furthermore, the concept of free will is greatly impacted. Indeed, the bootstrap paradox implies that all things are predetermined since the past is dependent on the future—a shocking implication.

Physically speaking, the bootstrap paradox also appears to violate the second law of thermodynamics. The former states that the entropy of isolated systems will either remain constant or increase but cannot decrease when left to a spontaneous evolution. Following the law, the state of the object or information traveling back and forth should deteriorate.

Although we could assume a reverse thermodynamic process where the state of the information is restored when traveling back and deteriorates when traveling forward, we cannot establish a clear origin to the object to begin. Therefore, it is difficult even to predict where a piece of information or object comes from and how it should evolve.

Solutions to the paradox

Understanding The Bootstrap Paradox and the Existence of Multiverse. 1
Image: MattLphotography/

A considered solution to the bootstrap paradox is the concept of a multiverse. A time traveler traveling back in time enters a duplicate of the world he left where the world is only identical up to the time they arrive, allowing them to modify the future freely as it is not predetermined. Furthermore, any actions of the time traveler will therefore not affect the original universe. 

The paradoxes don’t stop here

To conclude, all of these situations remain hypothetical. However, much more paradoxes relating to time travel populate the world of physics. For example, the grandfather paradox, a logical problem, states that if you were to travel back in time, you could kill your own grandfather, causing a problem in your genealogy and your own existence. All seemingly absurd and bearing extravagant solutions, these paradoxes lead scientists like Stephen Hawking to believe that time travel is impossible.

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J Leviathan
J Leviathan

When we travel either to the past or the future it isn’t in the same timeline. Just by making the jump opens a different timeline so the paradox is irrelevant.


How could travel to the past happen when the atoms that we are made of exist elsewhere in the past? You would have to duplicate all the subatomic particles that we are made of because that proton in that cell on the end of my nose was part of a water molecule in a blade of grass a year ago. If a multiverse, perhaps.

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