## Now, a computer that can work like a scientist to derive natural laws

April 3rd, 2009 - 12:27 pm ICT by ANIWashington, April 3 (ANI): Researchers at Cornell University, US, using a computer, have developed an algorithm which can derive natural laws from observed data, just like scientists.

What the researchers have done is to teach a computer to find regularities in the natural world that become established laws - yet without any prior scientific knowledge on the part of the computer.

They have tested their method, or algorithm, on simple mechanical systems and believe it could be applied to more complex systems ranging from biology to cosmology and be useful in analyzing the mountains of data generated by modern experiments that use electronic data collection.

Their process begins by taking the derivatives of every variable observed with respect to every other - a mathematical way of measuring how one quantity changes as another changes.

Then, the computer creates equations at random using various constants and variables from the data.

It tests these against the known derivatives, keeps the equations that come closest to predicting correctly, modifies them at random and tests again, repeating until it literally evolves a set of equations that accurately describe the behavior of the real system.

Technically, the computer does not output equations, but finds “invariants” - mathematical expressions that remain true all the time.

“Even though it looks like it’s changing erratically, there is always something deeper there that is always constant,” said Hod Lipson, Cornell associate professor of mechanical and aerospace engineering.

“That’s the hint to the underlying physics. You want something that doesn’t change, but the relationship between the variables in it changes in a way that’s similar to what we see in the real system,” Lipson explained.

Once the invariants are found, potentially all equations describing the system are available.

“All equations regarding a system must fit into and satisfy the invariants,” Schmidt said. “But of course we still need a human interpreter to take this step,” he added.

The researchers tested the method with apparatus used in freshman physics courses: a spring-loaded linear oscillator, a single pendulum and a double pendulum.

Given data on position and velocity over time, the computer found energy laws, and for the pendulum, the law of conservation of momentum.

Given acceleration, it produced Newton’s second law of motion.

The researchers point out that the computer evolves these laws without any prior knowledge of physics, kinematics or geometry.

According to researchers, computers will not make scientists obsolete, but will take over the grunt work, helping scientists focus quickly on the interesting phenomena and interpret their meaning. (ANI)

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