New definition returns meaning to information

October 23, 2018 by Jenna Marshall, Santa Fe Institute
A clownfish navigates a sea of information. Credit: Santa Fe Institute

A fish on the Great Barrier Reef continually acquires new information from its environment—the location of food, the murkiness of the water, and the sounds of distant ships, to name a few examples. But only some of that information is meaningful, in that it actually helps the fish survive. In various disciplines, from biology to artificial intelligence, identifying such meaningful, or "semantic," information is a key challenge. Yet a broadly applicable, fully formal definition of this kind of information has never been developed.

A new paper by the Santa Fe Institute's Artemy Kolchinsky, a postdoctoral fellow specializing in theory, and professor David Wolpert, a mathematician and physicist, proposes one. Taking cues from statistical physics and , they've come up with a definition that emphasizes how a particular piece of information contributes to the ability of a physical system to perpetuate itself—which in the context of common means its ability to survive. Semantic information, they write, is "the information that a physical system has about its environment that is causally necessary for the system to maintain its own existence over time."

For example, the location of food is semantic information to the Great Barrier Reef fish because it's essential for the fish's survival. But the sound of a distant ship does not contribute to the fish's viability, so it does not qualify as semantic information.

Kolchinsky and Wolpert hope that this new, formal definition of semantic information can help researchers sort the wheat from the chaff when trying to make sense of the information a physical has about its environment.

"Some information can be extraordinarily meaningful to an organism, while other information can have no meaning," Wolpert says. "While it seems obvious that this distinction is crucial for analyzing biological organisms, it has never been formalized. Moreover, to avoid the fraught issue of defining a 'biological organism,' we wanted our definition of meaningful information to be applicable to both living and non-living physical systems, such as rocks and hurricanes."

The researchers' fills a hole in information theory left by Claude Shannon, who intentionally omitted the issue of the "meaning" of information in his iconic paper that created the field, "A Mathematical Theory of Communication," in 1948.

In the realm of biology, understanding the role of semantic information could help answer some of the discipline's most intriguing questions, such as how the earliest life forms evolved, or how existing ones adapt, says Kolchinsky. "When we talk about fitness and adaptation, does increase over evolutionary time? Do organisms get better at picking up information that's meaningful to them?"

Explore further: An integrated visual and semantic neural network model explains human object recognition in the brain

More information: Artemy Kolchinsky et al, Semantic information, autonomous agency and non-equilibrium statistical physics, Interface Focus (2018). DOI: 10.1098/rsfs.2018.0041

Related Stories

Working group: What physical principles predict life?

October 29, 2015

We are immersed in life here on Earth, but life isn't found on the Moon. Nor has it arisen, so far as we know, anywhere else in the solar system. Why do some physical environments precipitate life, and why don't others?

What's the semantic organization of human language?

August 11, 2009

A Chinese semantic network with semantic (argument structure) annotation was built and investigated for finding its global statistical properties. The results show that semantic network is also small-world and scale-free ...

Recommended for you

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

Revealing the rules behind virus scaffold construction

March 19, 2019

A team of researchers including Northwestern Engineering faculty has expanded the understanding of how virus shells self-assemble, an important step toward developing techniques that use viruses as vehicles to deliver targeted ...

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...

Levitating objects with light

March 19, 2019

Researchers at Caltech have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces.


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (2) Oct 23, 2018
Semantic information, they write, is "the information that a physical system has about its environment that is causally necessary for the system to maintain its own existence over time."

Isn't this missing something? Let's say humans gather information about something that has no direct impact on them (e.g. astronomical observation of distant stars) but which might bring further knowledge which in turn might be integrated with other knowledge to enhance our future options. Does such information only become (retroactively?) meaningful/semantic at the point where it conforms to the above definition?

There can be meaning in (gathering) information which one only suspects might become relevant.
Spaced out Engineer
not rated yet Oct 23, 2018
Semantic constraints play a role only in determining which functions are explanatory in a given context. A creature has no need for meta-awareness of the modality it is performing, perhaps only the alignment of sensory somatic enactivism. Debatably just intrinsic awareness or non-doing.

Claiming any information perpetuates survival is a bold claim.

A lack of clarity might be the only reversible computation. Existentialism all the more anthropic for it. There is only one question, classical or conditional probabilities, right action its implementation.
not rated yet Oct 23, 2018
Comments disappearing in phone version but not in full version...
not rated yet Oct 23, 2018
They just don't show up after you press post, and textarea empties itself. iPhone X w safari, note to webdev.
not rated yet Oct 25, 2018
a_p & SOE, My interpretation of this article is that it pertains to a generic Public perception of knowledge. That the researchers lack the tools to measure a specific knowledge base such as astrophysics or engineering.

When the rest of us, the general populace, see photographs from the Hubble orbiting telescope? The great majority will ohh & ahh about "How pretty!". Then just accept that they are seeing what the Cosmos looks like.

When you look at the same images? You also ohh & ahh about "How pretty!".

However, you will take the next step & realize the images are falsified. To better display a range of information gathered across the spectrum of data collected.

That is not fraud. Anymore than it is when your physician shows you an MRI image of your interior. Most people do not have the training to interpret such information. However, it is reassuring emotionally, even if it is bad news. That is how our monkey brains are wired to respond.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.