How Can We Picture the Fourth Dimension? Brian Greene Explains.

Left-right, up-down, back-forth: These are the dimensional directions we're able to perceive. Theoretical physics posits that additional dimensions could exist beyond our perceptive reach.

Brian Greene: The possibility of dimensions of space beyond the three that we know about is an idea that — it cropped up in the early part of the 20th century and it has been with us ever since. Even our modern approach to unified theory, something called string theory, invokes the possibility of more dimensions than the three that we experience, right. So we all know about left-right, back-forth, and up-down, right. Those are the three dimensions that are all around us. We all move through them freely in day to day life. These other dimensions suggested by theoretical considerations. There is no experimental evidence for any of what I’m about to tell you. But the theoretical considerations suggest that in addition to left-right, back-forth, and up-down there may be other spatial dimensions. It’s hard to picture, like, where could they be? There doesn’t seem to be any room left and that’s really the point. They are new places that our experience doesn’t allow us to access directly, but according to these theoretical ideas, might be there.

I love a little analogy that helps to understand this. Think of a garden hose is one that we love to use. So think about a garden hose that’s nice and long. Now from far away, the garden hose is going to look one dimensional because that’s the only part that you have the visual acuity to see because the circular part is just too small for your feeble eyes to detect. But then if you take a pair of binoculars from a faraway vantage point, now you see that there is a circular dimension, a circular part that wraps around the garden hose that you missed when you just used your feeble senses. So dimensions can be big, obvious, and easy to see or they can be curled up and tiny, much more difficult to detect. Now the garden hose is an object in our universe. But this idea might apply to space itself, right. So it could be that left-right, back-forth, and up-down are the big easy-to-see dimensions like the horizontal extent of the garden hose. But just as the hose has a curled up dimension, maybe space itself has curled up dimensions all around us, just curled up to such a fantastically small size that we can’t see them with our eyes. We can’t see them even with today’s most powerful microscopes. But the possibility, according to the mathematics well-motivated by these attempts of realizing [Albert] Einstein’s dream of unified theory, the math suggests this as a real possibility that there may be more dimensions than the ones that we directly experience.

Left-right, up-down, back-forth: These are the dimensional directions we're able to perceive. Theoretical physics posits that additional dimensions could exist beyond our perceptive reach. In this video, string theorist and World Science Festival chairman Brian Greene dives head-first into the search for extra dimensions.

Michio Kaku: Genetic and digital immortality are within reach

Technology may soon grant us immortality, in a sense. Here's how.

Videos
  • Through the Connectome Project we may soon be able to map the pathways of the entire human brain, including memories, and create computer programs that evoke the person the digitization is stemmed from.
  • We age because errors build up in our cells — mitochondria to be exact.
  • With CRISPR technology we may soon be able to edit out errors that build up as we age, and extend the human lifespan.
Keep reading Show less

Active ingredient in Roundup found in 95% of studied beers and wines

The controversial herbicide is everywhere, apparently.

(MsMaria/Shutterstock)
Surprising Science
  • U.S. PIRG tested 20 beers and wines, including organics, and found Roundup's active ingredient in almost all of them.
  • A jury on August 2018 awarded a non-Hodgkin's lymphoma victim $289 million in Roundup damages.
  • Bayer/Monsanto says Roundup is totally safe. Others disagree.
Keep reading Show less

Robot pizza delivery coming later this year from Domino's

The pizza giant Domino's partners with a Silicon Valley startup to start delivering pizza by robots.

Nuro
Technology & Innovation
  • Domino's partnered with the Silicon Valley startup Nuro to have robot cars deliver pizza.
  • The trial run will begin in Houston later this year.
  • The robots will be half a regular car and will need to be unlocked by a PIN code.

Would you have to tip robots? You might be answering that question sooner than you think as Domino's is about to start using robots for delivering pizza. Later this year a fleet of self-driving robotic vehicles will be spreading the joy of pizza throughout the Houston area for the famous pizza manufacturer, using delivery cars made by the Silicon Valley startup Nuro.

The startup, founded by Google veterans, raised $940 million in February and has already been delivering groceries for Kroger around Houston. Partnering with the pizza juggernaut Domino's, which delivers close to 3 million pizzas a day, is another logical step for the expanding drone car business.

Kevin Vasconi of Domino's explained in a press release that they see these specially-designed robots as "a valuable partner in our autonomous vehicle journey," adding "The opportunity to bring our customers the choice of an unmanned delivery experience, and our operators an additional delivery solution during a busy store rush, is an important part of our autonomous vehicle testing."

How will they work exactly? Nuro explained in its own press release that this "opportunity to use Nuro's autonomous delivery" will be available for some of the customers who order online. Once they opt in, they'll be able to track the car via an app. When the vehicle gets to them, the customers will use a special PIN code to unlock the pizza compartment.

Nuro and its competitors Udelv and Robomart have been focusing specifically on developing such "last-mile product delivery" machines, reports Arstechnica. Their specially-made R1 vehicle is about half the size of a regular passenger car and doesn't offer any room for a driver. This makes it safer and lighter too, with less potential to cause harm in case of an accident. It also sticks to a fairly low speed of under 25 miles an hour and slams on the breaks at the first sign of trouble.

What also helps such robot cars is "geofencing" technology which confines them to a limited area surrounding the store.

For now, the cars are still tracked around the neighborhoods by human-driven vehicles, with monitors to make sure nothing goes haywire. But these "chase cars" should be phased out eventually, an important milestone in the evolution of your robot pizza drivers.

Check out how Nuro's vehicles work: