What Are the Limits of Computing?

What constraints govern the physical process of computing? Is a minimum amount of energy required per logic step? There seems to be no minimum, but some other questions are open.

What's the Latest Development?


A computation, whether it is performed by electronic machinery or an abacus or in the brain, is a physical process. It is therefore subject to physical laws, but what are the physical limits of computation? And what do quantum computations imply? "Even in quantum mechanics extremely fast events can take place without any loss of energy. Our confidence that quantum mechanics allows computing without any minimum expenditure is bolstered when we remember that Benioff and others have developed models of reversible quantum-mechanical computers, which dissipate no energy and obey the laws of quantum mechanics."

What's the Big Idea?

What did computational theory look like in 1985? Many old questions are still perplexing computer scientists today: "How much energy must be expended to perform a particular computation? How long must it take? How large must the computing device be? In other words, what are the physical limits of the process of computation? So far it has been easier to ask these questions than to answer them. To the extent that we have found limits, they are terribly far away from the real limits of modern technology. ... We are looking for general laws that must govern all information processing, no matter how it is accomplished."

Study: 50% of people pursuing science careers in academia will drop out after 5 years

That's a sharp increase from the 1960s when it took the same share of scientists an average of 35 years to drop out of academia.

Pixabay
Surprising Science
  • The study tracked the careers of more than 100,000 scientists over 50 years.
  • The results showed career lifespans are shrinking, and fewer scientists are getting credited as the lead author on scientific papers.
  • Scientists are still pursuing careers in the private sector, however there are key differences between research conducted in academia and industry.
Keep reading Show less

Why being busy is a modern sickness

We have to practice doing nothing more often.

Photo: Shutterstock
Personal Growth
  • Constantly being busy is neurologically taxing and emotionally draining.
  • In his new book, Jon Kabat-Zinn writes that you're doing a disservice to others by always being busy.
  • Busyness is often an excuse for the discomfort of being alone with your own thoughts.
Keep reading Show less

New ‘microneedle patch’ could help heart attack patients regrow tissue

The bold technique involves surgically implanting a so-called microneedle patch directly onto the heart.

Red human heart against a yellow background (Getty Images)
Surprising Science
  • Heart attacks leave scar tissue on the heart, which can reduce the organ's ability to pump blood throughout the body.
  • The microneedle patch aims to deliver therapeutic cells directly to the damaged tissue.
  • It hasn't been tested on humans yet, but the method has shown promising signs in research on animals.
Keep reading Show less