Monthly Archives: September 2020

As humans, we take time for granted. Were born into an innate understanding of the passage of events because its essential to our survival. But AI suffers from no such congenital condition. Robots do not understand the concept of time.

State of the art AI systems only understand time as an implicit construct (we program it to output time relevant to a clock) or as an explicit representation of mathematics (we use the time it takes to perform certain calculations to instruct its understanding of the passage of events). But an AI has no way of understanding the concept of time itself as we do.

Time doesnt exist in our classical reality in a physical, tangible form. We can check our watch or look at the sun or try and remember how long its been since we last ate, but those are all just measurements. The actual passage of time, in the physics sense, is less proven.

In fact, scientists have proven that times arrow a bedrock concept related to the classical view of time doesnt really work on quantum computers. Classical physics suffers from a concept called causal asymmetry. Basically, if you throw a bunch of confetti in the air and take a picture when each piece is at its apex, itll be easier for a classical computer to determine what happens next (where the confetti is going) than what happened before (what direction the confetti would travel in going backwards through time).

Quantum computers can perform both calculations with equal ease, thus indicating they do not suffer causal asymmetry. Times arrow is only relevant to classical systems of which the human mind appears to be, though our brains are almost certainly quantum constructs.

Where things get most interesting is if you consider the addition of artificial intelligence into the mix. As mentioned previously, AI doesnt have a classical or quantum understanding of time: time is irrelevant to a machine.

But experts such as Gary Marcus and Ernest Davis believe an understanding of time is essential to the future of AI, especially as it relates to human-level artificial general intelligence (AGI). The duo penned an op-ed for the New York Times where they stated:

In particular, we need to stop building computer systems that merely get better and better at detecting statistical patterns in data sets often using an approach known as deep learning and start building computer systems that from the moment of their assembly innately grasp three basic concepts: time, space and causality.

While the statement is intended as a sweeping indictment on relying on bare bones deep learning systems and brute force to achieve AGI, it serves as a bit of a litmus test as to where the computer science community is at when it comes to AI .

Currently, were building classical AI systems with the hopes theyll one day be robust enough to mimic the human mind. This is a technology endeavor, meaning computer experts are continuously pushing the limits of what modern hardware and software can do.

The problem with this approach is that its creating a copy of a copy. Quantum physics tells us that, at the very least, our understanding of time is likely different from what might be theultimate universal reality.

How close can robots ever come to imitating humans if they, like us, only think in classical terms? Perhaps a better question is: what happens when AI learns to think in quantum terms while us humans are still stuck with our classical interpretation of reality?

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Published September 17, 2020 18:52 UTC

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Quantum and classical computers handle time differently. What does that mean for AI? - The Next Web

For the better part of a century, the world's greatest minds have struggled with the mathematical certainty that objects can be in multiple positions at the same time before something causes them to snap into place.

A number of physicists have wondered if good old gravity is responsible for forcing the particle equivalent of a roulette ball to settle into its metaphorical pocket. That's looking a little less likely in the wake of a new experiment.

Researchers from across Europe recently tested a potential explanation of the apparent collapse of a waveform, determined not by observations or weirdly branching multiverses, but by the geometry of spacetime.

It's an idea that has its roots in a paperpublished back in 1966 by the Hungarian physicist Frigyes Karolyhazy, championed decades later by renowned minds like Roger Penrose and Lajos Disi.

In fact, it was Disi who teamed up with a handful of scientists to determine if we could blame gravity for one of quantum physics' most brain-numbing paradoxes.

"For 30 years, I had been always criticised in my country that I speculated on something which was totally untestable," Disi told Science Magazine's George Musser.

New technology has finally made the untestable a possibility. But to understand how it works, we need to take a brief dive into quantum insanity.

Back in the early 20th century, theorists modelled particles as if they were waves in order to reconcile what they were learning about atomics and light.

These particles weren't quite like waves rippling across the surface of a pond, though. Think of the curving line you might draw on a graph to describe your chances of winning a bet in a dice game.

To some physicists, this whole gambling analogy was just a convenient fudge-factor, to be later resolved when we worked out more about the fundamental nature of quantum physics.

Others were adamant quantum physics is as complete as it gets. Meaning it really is a muddy mess of maybes down in the depths of physics.

Explaining how we get from a rolled dice to a clearly defined number describing things like particle spin, position, or momentum is the part that has had everybody stumped.

The famous Swiss physicist Erwin Schrdinger was firmly on team 'fudge factor'.

He came up with that outrageous thought experiment involving a hidden cat that was alive and dead at the same time (until you looked at it), just to show just how nuts the whole 'undecided reality' thing was.

And yet here we are, a century on, and still superposition the idea of objects like electrons(or bigger) occupying multiple states and positions at once until you measure them is a core feature of modern physics.

So much so, we're developing a whole branch of technology quantum computing around the concept.

To avoid needing to invoke half-baked notions of consciousness or infinite co-existing versions of reality to explain why many possibilities become one when we look at a particle, something less whimsical is needed for quantum probability to collapse into.

For physicists like Penrose and Disi, gravity might be that very thing.

Einstein's explanation of this force rests upon a curving fabric of three-dimensional space woven with time's single dimension.Frustratingly, a quantum description of this 'spacetime' continues to elude theorists.

Yet this firm discrepancy between the two fields makes for a good backbone to pull waves of possibility into line.

Penrose's version of this idea rests on the assertion that it takes different amounts of energy for particles to persist in different states.

If we follow Einstein's old E=mc^2 rule, that energy difference manifests as a difference in mass; which, in turn, influences the shape of spacetime in what we observe as gravity.

Given enough of a contrast in all possible states, spacetime's immutable shape will ensure there's a substantial cost to pay, effectively choosing a single low-energy version of a particle's properties to yank into place.

It's an alluring idea, and luckily one with a potentially testable component.For all purposes, that snap should affect a particle's position.

"It is as if you gave a kick to a particle," Frankfurt Institute for Advanced Studies physicist Sandro Donadi told Science Magazine.

Kick an electron enough and you'll force it to cry photons of light. Logically, all that's left is to create a kind of Schrdinger's cat experiment by locking the right kind of material inside a lead box, buried far from the confounding effects of radiation, and listen for its cries. That material, in this case, is germanium.

If Penrose's sums are right, a crystal of germanium should generate tens of thousands of photon flashes over several months as its superpositioned particles settle into measured states.

But Disi and his team didn't observe tens of thousands of photons.

Over a two month period when they conducted the experiment underground five years ago at INFN Gran Sasso National Laboratory, they measured barely several hundred just what you'd expect from the radiation that managed to leak through.

Penrose isn't too worried. If gravity were to cause particles to emit radiation on collapse, it might run against the Universe's tightly controlled laws of thermodynamics, anyway.

Of course, this isn't the end of the story. In future experiments, gravity might yet be shown to be responsible for flattening quantum waves. Right now, anything seems possible.

This research was published in Nature Physics.

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The Fate of Schrdinger's Cat Probably Isn't in The Hands of Gravity, Experiment Finds - ScienceAlert

People thought what we did was totally wacky, recalls Thomas Ebbesen from the University of Strasbourg in France. When we tried to submit [our 2012 Angewandte Chemie] paper,1 there was one referee report that was very short and simply said: This is not science, this is science fiction.

For many, Ebbesens study might indeed sound like make-believe. His team showed it could change the rate and yield of a photoisomerisation reaction by instead of carrying it out in a beaker putting it in a small space between two mirrors. The space contained no chemical catalyst, nothing obvious that might make this possible. What the researchers did is tap into the power of the vacuum field, a weird quantum mechanical soup that surrounds everything.

2012 was an eye-opener for everyone, says Felipe Herrera who leads a molecular quantum technology group at the University of Santiago, Chile. Nobody believed this, and people spent maybe two or three years until they could reproduce the results.

Although vacuum-field catalysis is still in its infancy and doesnt have any practical applications yet, it could bring catalyst-free catalysis, ultra-selective carbon dioxide reduction and new photosensitisers. It might become a powerful tool to steer chemical reactions akin to photocatalysis. I think this field is going to have far-reaching implications, says Herrera.

It is the view of modern physics that there is no such thing as truly empty space, wrote physicist Brian Skinner from Ohio State University, US, on his blog over a decade ago. Physicists discovered that the universe is filled with an energetic soup, boiling and bubbling with particles that appear as fast as they disappear. Although this almost sounds like a ridiculous return to the long-discarded aether theory, experimental results like the Casimir effect have long since established the vacuum fields existence.

But what has been firmly in the realm of physics is now starting to interest chemists, who hope to one day catalyse reactions with this vacuum field. They do this by creating polaritons, hybrid particles that are part light, part matter. They form even in the absence of light when molecules strongly interact with the so-called virtual photons spontaneously thrown up by the vacuum field.

Creating polaritons out of light and matter is not unlike creating a molecule out of two atoms, Herrera explains. Bring two atoms close enough together and they form a molecule, a new entity with new orbitals, and new chemical properties. Similarly, polaritons often have dramatically different reactivities to their parent molecules so dramatic in fact that they could be likened to a new state of matter.

Although a small field, it has seen an uptick in attention from the scientific community. According to Web of Science, the number of studies containing the keyword molecular polariton has doubled, rising from less than 25 in 2017 to more than 50 in 2019. Since the start of the Covid-19 lockdown, around 200 scientists have been attending weekly webinars on polariton chemistry hosted by researchers at the University of California San Diego, US.

I think this field will open many minds, especially among experimental chemistry colleagues, says Herrera. Thats why I like this field so much, because its a bridge between maybe 50 or 60 years of quantum optics and perhaps 100 years of physical chemistry.

Making molecules interact with the vacuum field is as easy as putting them in a cavity. Simply put, optical cavities consist of two mirrors facing each other and separated by only a few nanometres in some cases. Cavities are a major component of lasers where they form a resonator for light waves. But in the dark, they can be used to create polaritons. Free space is infinite and vacuum field fluctuations are very tiny, which is why we dont see strong coupling in free space, Herrera explains. If you confine the field into tiny spaces, then these vacuum fluctuations are very large.

The dream would be to have super selective chemical protocols using cavities

Joel Yuen-Zhou,University of California San Diego

The cavitys size dictates the wavelength of the virtual photons that can live inside it. Matching this wavelength to be resonant with a molecules bond vibration or an electronic transition creates the conditions for lightmatter mixing, forming molecular polaritons.

An experiment to create polaritonic states might seem surprisingly crude: silver-coated glass slides serve as mirrors sandwiching a layer of target molecules. The setup is held together with screws, so the cavitys resonance frequency can be fine-tuned by minutely changing the mirror-to-mirror distance with a screwdriver.

Before 2012, physicists had modified molecules optical properties like light emission rates in this way. But Ebbesens team showed for the first time that sticking molecules inside a cavity can also alter their chemical properties. It was a proof of concept, and other studies conducted since hinted at the tantalising prospect of controlling chemistry in an entirely new way. It was revolutionary, certainly challenging how we think about chemical reactions, says Wei Xiong who works on ultrafast spectroscopy at the University of California San Diego in the US.

Although synthetic chemists might not see cavity catalysts in the catalogues of their favourite chemicals suppliers anytime soon, there has been progress in the field. In a preprint published in 2018, a team around Hidefumi Hiura from Japans NEC Corporation reported a 10,000-fold increase in the rate of ammonia borane hydrolysis when it was put inside a cavity containing water polaritons.2 Last year, the groups of Ebbesen and Strasbourg colleague Joseph Moran showed how coupling to the vacuum field changes the product ratio in a reaction that can produce two different products.3 And earlier this year, scientists led by Kenji Hirai and Hiroshi Ujii from Hokkaido University, Japan, tuned a cavity to the carbonyl stretching motion of ketones and aldehydes, slowing down the rate of a Prins cyclisation by up to 70%.4

People who learn quantum electrodynamics dont often sit in advanced organic chemistry classes and vice versa

Prineha Narang, Harvard University

How far could we push these changes? wonders computational materials scientist Prineha Narang from Harvard University, US. Could we have something that is completely selective to one product and shuts off all the other products, in particular for reactions that are of technological relevance? Carbon dioxide reduction would be one of those reactions, she adds.

While polaritonic chemistry might not become the next big thing for industrial synthesis, flow setups that funnel reagents through a cavity could provide a solution to scaling up reactions. I think it would be very nice to see controlling chemistry of triplet states, suggest Herrera. There are many photosensitisers that are used in industry that rely on electrons becoming unpaired.

The dream would be to have super selective chemical protocols using cavities, says Joel Yuen-Zhou who works on polariton chemistry at the University of California San Diego, US. This is still under development, but it might be the case that with appropriate photonic architectures, this will be possible.

However, so far, researchers havent been able to show that vacuum-field catalysis can do reactions that are impossible or hard to do with other types of chemistry. This is what we would love to demonstrate, says Ebbesen. But for the moment, were trying to understand the underlying mechanism of why some reactions are enhanced and some reactions are slowed down.

For the most part, scientists still dont understand the microscopic mechanism underlying vacuum-field catalysis. When molecules sit inside a cavity, only a small fraction less than 1% are actually occupying polaritonic states. The rest are in dark states, which can be likened to non-bonding orbitals. How exactly macroscopic changes happen with most molecules remaining dark is still a mystery.

Sometimes the evidence is confusing or contradictory, says Herrera. The mechanism that colleagues conclude in one paper doesnt work for a very similar molecule in another paper. Initially, researchers tried to reason that polaritons unpredictable behaviour was due to energetic variations like changes in reaction barrier.

However, first theoretical5 and then experimental6 evidence like the fact that like polar bonds are more strongly influenced than non-polar ones now point to vibrational symmetry as the key to solving the dark state paradox. Vibrational modes can be naturally self-excited or de-excited by the vacuum field depending on their dipolar symmetry, explains Herrera though how this links to reaction rate changes remains unclear.

A model that reproduces let alone predicts how different compounds behave is still missing. What scientists are after is a set of rules not unlike the WoodwardHoffman rules: something simple that nevertheless reflects the complexity of the underlying quantum mechanics.

Most reactions studied so far are slowed down by cavities rather than accelerated not something chemists usually look for in a catalyst. But why this happens and how they can be speeded up remain open questions, says Xiong. Only if we can understand what knobs we need to turn, we can control the selectivity, he adds.

Still, the prospect of doing reactions by simply putting reagents between two mirrors remains intriguing. Whether this is going to be a universal tool or not I think, as of now, I would say no but I wouldnt discard it in the future, says Yuen-Zhou. Just like with photoredox catalysis, you just need to find the right class of reactions.

There might certainly be something said for more people becoming involved and working together within this field. People who learn quantum electrodynamics dont often sit in advanced organic chemistry classes and vice versa theres a gap to be bridged, Narang says. But of course thats also where a lot of exciting discoveries come from.

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Hybrid lightmatter particles offer tantalising new way to control chemistry - Chemistry World