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Bizarre armor from Mycenaean Greece turns out to have been effective

✇Ars Technica
By: Jacek Krywko
30 May 2024 at 06:55
Two images of a person wearing unusual armor that covers his torso in bands of metal, with a deep collar and high helmet.

Enlarge / Armor based on the Dendra artifact being tested. (credit: Andreas Flouris and Stavros Petmezas)

The Dendra armor, one of the oldest suits of bronze armor ever found, had been considered a purely ceremonial piece. It seemed impossible to use in battle due to its cumbersome design.

It took over a decade of research, elaborate numerical models, and 13 Greek marines fighting in it from dawn till dusk to prove it was surprisingly good at its job, despite its odd appearance. “This made the Mycenaean warriors some of the best equipped in the Eastern Mediterranean in the Late Bronze Age,” says professor Andreas Flouris, a researcher at the University of Thessaly, who led the study.

Mycenaean Conquests

“The Mycenaeans were an ancient Greek civilization that flourished during the late Bronze Age, roughly from 1600 BC to 1100 BC,” explains Ken Wardle, an archeologist at the University of Birmingham and co-author of the study. With their power centered around major cities like Mycenae, Thebes, Tiryns, and Pylos, the Mycenaeans peaked between 1400 BCE and 1200 BCE, when they occupied much of mainland Greece and gained influence over Aegean islands and Asia Minor.

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Whale songs have features of language, but whales may not be speaking

✇Ars Technica
By: Jacek Krywko
22 May 2024 at 11:55
A group of sperm whales and remora idle near the surface of the ocean.

Enlarge (credit: wildestanimal)

Whales use complex communication systems we still don’t understand, a trope exploited in sci-fi shows like Apple TV’s Extrapolations. That show featured a humpback whale (voiced by Meryl Streep) discussing Mahler’s symphonies with a human researcher via some AI-powered inter-species translation app developed in 2046.

We’re a long way from that future. But a team of MIT researchers has now analyzed a database of Caribbean sperm whales’ calls and has found there really is a contextual and combinatorial structure in there. But does it mean whales have a human-like language and we can just wait until Chat GPT 8.0 to figure out how to translate from English to Sperm-Whaleish? Not really.

One-page dictionary

“Sperm whales communicate using clicks. These clicks occur in short packets we call codas that typically last less than two seconds, containing three to 40 clicks,” said Pratyusha Sharma, a researcher at the MIT Computer Science and Artificial Intelligence Laboratory and the lead author of the study. Her team argues that codas are analogues of words in human language and are further organized in coda sequences that are analogues of sentences. “Sperm whales are not born with this communication system; it's acquired and changes over the course of time,” Sharma said.

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Nova explosion visible to the naked eye expected any day now

✇Ars Technica
By: Jacek Krywko
21 May 2024 at 10:13
Image of a blue sphere, surrounded by blue filaments, and enclosed in a partial sphere of pink specks.s

Enlarge / Aftermath of a nova at the star GK Persei. (credit: NASA/CXC/RIKEN/STScI/NRAO/VLA)

When you look at the northern sky, you can follow the arm of the Big Dipper as it arcs around toward the bright star called Arcturus. Roughly in the middle of that arc, you'll find the Northern Crown constellation, which looks a bit like a smiley face. Sometime between now and September, if you look to the left-hand side of the Northern Crown, what will look like a new star will shine for five days or so.

This star system is called T. Coronae Borealis, also known as the Blaze Star, and most of the time, it is way too dim to be visible to the naked eye. But once roughly every 80 years, a violent thermonuclear explosion makes it over 10,000 times brighter. The last time it happened was in 1946, so now it’s our turn to see it.

Neighborhood litterbug

“The T. Coronae Borealis is a binary system. It is actually two stars,” said Gerard Van Belle, the director of science at Lowell Observatory in Flagstaff, Arizona. One of these stars is a white dwarf, an old star that has already been through its fusion-powered lifecycle. “It’s gone from being a main sequence star to being a giant star. And in the case of giant stars, what happens is their outer parts eventually get kind of pushed into outer space. What’s left behind is a leftover core of the star—that’s called a white dwarf,” Van Belle explained.

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Exploration-focused training lets robotics AI immediately handle new tasks

✇Ars Technica
By: Jacek Krywko
10 May 2024 at 14:22
A woman performs maintenance on a robotic arm.

Enlarge (credit: boonchai wedmakawand)

Reinforcement-learning algorithms in systems like ChatGPT or Google’s Gemini can work wonders, but they usually need hundreds of thousands of shots at a task before they get good at it. That’s why it’s always been hard to transfer this performance to robots. You can’t let a self-driving car crash 3,000 times just so it can learn crashing is bad.

But now a team of researchers at Northwestern University may have found a way around it. “That is what we think is going to be transformative in the development of the embodied AI in the real world,” says Thomas Berrueta who led the development of the Maximum Diffusion Reinforcement Learning (MaxDiff RL), an algorithm tailored specifically for robots.

Introducing chaos

The problem with deploying most reinforcement-learning algorithms in robots starts with the built-in assumption that the data they learn from is independent and identically distributed. The independence, in this context, means the value of one variable does not depend on the value of another variable in the dataset—when you flip a coin two times, getting tails on the second attempt does not depend on the result of your first flip. Identical distribution means that the probability of seeing any specific outcome is the same. In the coin-flipping example, the probability of getting heads is the same as getting tails: 50 percent for each.

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