Almost a century has passed since scientists destroyed the Universe.
Through a complex mix of experiment and theory, physicists have discovered a machine built on the mathematics of probability that slips far below the surface of reality.
Referred to in vague terms as the Copenhagen interpretationaccording to the theory underlying quantum mechanics, everything can be described as a possibility – until we are forced to describe it as an actuality.
But what does this mean?
Despite decades of experimentation and philosophizing, the gap between the disordered properties of a quantum system and a scale we can all see with our eyes has narrowed almost entirely. For all the talk about collapsing waveforms, cats in boxes, and observer effects, we are no closer to understanding the nature of reality than those early physicists in the late 1920s.
However, some researchers think that clues can be found in the space between quantum physics and another majestic theory that was born in the early 20th century – Einstein’s famous general theory of relativity.
Last yeara small group of physicists from the University of Chicago argued for the mere existence of a black hole in a nearby area that pulls the strings of a mass in a blur of quantum states and forces it to choose a single fate.
Now they’re back with a follow-up prediction, showing their views on different types of horizons, in a pre-print ahead of the peer review.
Imagine a small piece of matter emerging from the darkness inside a closed box. Unseen, it exists in a blur of maybes. It has no single location in the shadows, no specific rotation, no specific momentum. Essentially, any light it emits also depends on an infinite spectrum of possibility.
This particle vibrates with a potential in a wave that theoretically propagates to infinity. It is possible to compare this spectrum of possibilities against itself in the same way that a wave on the surface of a pond can be split and recombined to form a recognizable interference pattern, in effect.
However, every bump and bump in this ripple as it spreads out entangles it with another, limiting the range of possibilities available to it. Its interference pattern changes in dramatic ways, confining its outcomes to a process physicists describe as decoherence, or decoherence.
It is this process that physicists Daine Danielson, Gautam Satishchandran, and Robert Wald considered in a thought experiment that would lead to an intriguing paradox.
A physicist peering inside the box to see the light emitted by the particle will inevitably involve themselves and their environment in hidden particle waves, which will cause some degree of decoherence.
But what if there was a second person looking over their shoulder, catching the light emitted by the particle with their own eyes? Also, by involving themselves in the light emitted by the particle, they can further suppress those possibilities in the particle wave, and change it anyway.
And what if the second observer is standing on a distant planet, light-years away, looking at the box through a telescope? This is where it gets weird.
Despite the years it took for the electromagnetic ripples of light to emerge from the box, a second observer would still be able to join the particle. According to quantum theory, this should also cause a noticeable change in the particle’s wave, one that the first observer would see before their colleague on a distant world even started setting up their telescope.
But what if the second observer hid inside a black hole? Light from the box could easily slide past its horizon, falling into the depths of fragmented space-time, but according to the rules of general relativity, there is no way that information about its entangled fate with a second observer can re-penetrate outwards.
Either we know quantum physics wrong, or we have some serious problems to solve with general relativity.
or, according to Danielson, Satishchandran, and Wald, our second observer was unrelated. That line-of-no-return that surrounds a black hole, known as the event horizon, acts as an observer itself, eventually causing the decay of, well, almost everything. Like a crowd of giant eyes throughout the cosmos, watching the Universe unfold.
Still crawling? It just gets worse.
Black holes are not the only phenomena where space-time stretches a one-way-street. Any sufficiently accelerating object that approaches the speed of light, in fact, will experience some sort of horizon from which the information it emits cannot possibly return.
According to the trio’s latest study, the ‘Rindler horizons‘ can also produce a similar type of decoherence in quantum states.
This does not mean that the Universe is conscious in any way. Conversely, the conclusions could lead to objective theories of how quantum states resolve at absolute scales, and perhaps where gravity and quantum physics meet in a single general theory of physics.
The Universe is still broken, for now at least.
All we can say is watch this space.
This research was published in arXiv.