Time’s Arrow and Growing Old Is Just A State of Mind

While we are increasingly being asked to refine our view of the world and the universe in which we live, one thing that we hold as constant is time. People often say things like “you can’t turn back the hands of time” or “you can’t escape getting older.” A new paper published in the journal Annalen der Physik, however, challenges this and if its authors Dmitry Podolsky and Robert Lanza, theoretical physicists at Harvard University, are correct in their assumptions, then it could turn out that aging is all just in our heads.

The concepts of time presented in the paper are rather complex, so let’s try to break them down point by point as simply as possible:

Quest for a Theory of Quantum Gravity

The theories of relativity and quantum mechanics work on vastly different scales, with the former describing large objects moving at large distances (e.g. planets, stars, galaxies, universe), while the latter describes reality when observed at extremely close proximity (e.g. atoms, electrons). As a result, relativity is concerned with gravity, and quantum mechanics with the other three forces of nature, namely electromagnetism, and the weak and strong nuclear forces.

Unfortunately, they both give incompatible descriptions of reality, with the world of relativity producing more continuous and deterministic rules, while in quantum mechanics outcomes are more probabilistic than definite. This has given rise to the problem of how to reconcile these two great, but seemingly incompatible theories of physics within an all-encompassing unifying theory of “quantum gravity.”

Collapse of the Wave Function

One aspect of quantum gravity that’s perplexing is “wave function collapse.” You can think of the problem this way–a light bulb is either lit or unlit at any given time; however, quantum mechanics holds that the light can also exist in a “superposition” of both states (“entangled”), even though we can’t perceive it. While scientific experiments have confirmed that entangled states are a feature of the microscopic world, a theory is needed to explain why we do not see macroscopic objects in the same way. In other words, despite Schrödinger’s famous cat experiment, in reality, people perceive the animal to be either dead or alive, but not both at the same time.

Scientists have explained why this is so in terms of “wave function collapse,” a process in which our own measuring and labeling of a phenomenon cause a loss of its quantum coherence; we perceive it and give it a name as either one thing or another, never both at once, and so all physical possibilities then become reduced to a single possibility as perceived by an observer.

Is Time due to Wave Function Decoherence?

Time's Arrow and Growing Old Is Just A State of MindAccording to the pioneering physicist John Wheeler, time itself is due to the “decohesion” of the wave function of subatomic particles, with gravity then creating the arrow of time as the particles move from the quantum realm to that of classical mechanics. Nevertheless, Podolsky and Lanza argue that gravity is not a strong enough force to cause time to move in a past-to-future direction, or to explain why there is a “lack of quantum entanglement in our ordinary, everyday macroscopic world.”

In fact, all the fundamental laws of physics with the exception of the Second Law of Thermodynamics (entropy) are valid whether you move time forward or backward, resulting in the second law being used to describe the “one-way direction” of time’s arrow, and the movement from order to disorder. As Lee Billings stated in Scientific American:

“Whether through Newton’s gravitation, Maxwell’s electrodynamics, Einstein’s special and general relativity, or quantum mechanics, all the equations that best describe our Universe work perfectly if time flows forward or backward.”

As a result, there has long been a discussion about whether or not time is actually real, or just subjective. Many scientists believe that all moments in time are equally real, and as Einstein once famously said:

“The distinction between the past, present and future is only a stubbornly persistent illusion.”

Time is a Function of the Observer’s Memory

The new paper published in the Annalen der Physik is the first to offer a real tangible explanation of why we see time as only moving in one direction rather than the past, present, and future all existing together.

The paper holds that it is because of the way we form memories that this happens. If we experience our future, for whatever reason, our brains cannot recall it. We are only able to remember what has happened in the past. We end up with a running record or history of things that we can recall, but this paper argues that that does not mean we are not also existing in the future but without any imprint being left on ourselves.

The finding suggests that even in a corner of the universe where time was flowing from the future to the past, an observer would still perceive it as flowing from the past to the future. As Robert Lanza subsequently explains:

“We observers have memory and can only remember events which we have observed in the past. Quantum mechanical trajectories ‘future to past’ are associated with erasing of memory, since any process which decreases entropy (decline in order) leads to the decrease of entanglement between our memory and observed events. Thus, a ‘brainless’ observer — that is, an observer without the ability to store observed events — does not experience time or a world in which we age.”


Based on their theory, Dmitry Podolsky in the new Annalen der Physik paper concludes that aging itself is not real but rather a state of mind, something that has been printed on countless t-shirts for years now. In other words, the past, present, and future all exist simultaneously in a superposition, and the way we experience the passage of time is just an illusion. Maybe one day in the future we’ll have real proof of this. Or maybe we already do but just don’t remember!

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