Language Selection

English French German Italian Portuguese Spanish

Physicist throws time-travel theories a curve

Filed under
Sci/Tech

What do you get when you join a 1981 DeLorean, a "flux capacitor" and a digital dial set to Nov. 5, 1955? If you're the character of Dr. Emmett Brown in the 1985 movie Back to the Future, you've created a time machine.

The possibility of time travel has occupied the fantasies of philosophers, authors, children and directors. But to some physicists, it's more than pure fancy.

In the July issue of Physical Review Letters, Amos Ori, professor of physics at the Technion, the Israel Institute of Technology in Haifa, argues that the laws of physics don't stand in the way of building a time machine.

Ori hasn't created, or even designed, a physical time machine. He instead constructed a situation — a mathematical model — in which the laws of physics will make one for him.

"I write (the situation) mathematically. That doesn't mean that I know how to implement it practically." However, he says, if inhabitants of some highly advanced civilization could set up the conditions he describes, they might be able to travel in time.

The time machine Ori proposes isn't quite like the phone booth in Bill & Ted's Excellent Adventure or Back to theFuture's DeLorean. Ori's solution forms a closed, timelike curve. It's a bit like a song that never ends. Think of each musical note as a point in space. As you sing the notes, you move forward in time. You can travel around the curve — sing the song — but when you get to the end, you are also at the beginning.

"If you had a closed, timelike curve, that means that something could run around it forever and ever, always going to the future but always coming back to the beginning," says Ted Jacobson, professor of physics at the University of Maryland.

Ori isn't the first physicist to create a theoretical time machine. Unlike previous models, Ori's proposal doesn't require any unknown matter or energy. The previous theories were forced to use unrealistic negative energy to warp space and time.

Ori's plan requires absolute emptiness — a vacuum. That means that, in principle, a closed, timelike curve could even happen naturally, possibly through cataclysmic astronomical collisions in the abyss of space.

It is difficult for experts to imagine the exact conditions, but extremes in the universe, such as super-dense black holes, could create the conditions necessary for the formation of a time machine.

When Einstein declared that space and time were intimately connected, time travel became a physical possibility. If you could zip around like a beam of light, you wouldn't age, but physics won't let that happen. It remains to be seen whether physics will allow time travel, but Ori's work suggests it will.

Einstein opened the door for the scientific pursuit of a time machine, and physicists are searching for solutions. Ori says maybe it's possible, but "this isn't something that we are going to construct soon."

By Michelle Lefort
USA TODAY

More in Tux Machines

Matching databases to Linux distros

Relational database management systems (RDBMSs) aren’t the sort of thing to get most folk out of bed in the morning – unless, of course, you happen to think they’re one of the most brilliant concepts ever dreamed up. These days you can’t sneeze without someone turning it into a table value in a database somewhere - and in combination with the freely available Linux operating system, there’s no end to them. Most Linux distros make it almost trivial to add popular DBMSs to your system, such as MySQL and MariaDB, by bundling them in for free in their online app stores. But how do you tell which combination - which Linux distro and which DBMS - will give you the best performance? This week we've revved up the Labs servers to ask the question: what level of performance do you get from OS repository-sourced DBMSs? Read more

The Curious Case of Raspberry Pi Consumerism

I find the attitude of many within the Raspberry Pi community to be strange and offensive. I first discovered this odd phenomenon (odd because it contradicts the ethos of the project's academic foundations) back when it first started, as many within the Raspberry Pi community took an extremely hostile attitude toward academic freedom, apparently in defence of various parties' highly dubious intellectual monopolies (Broadcom and MPEG-LA, for example). I pointed out the irony and hypocrisy of their attitude at the time, explaining that they were more than happy to leech Free (as in freedom) Software for their own benefit, but then balked at the prospect of freely sharing the results, and in particular this contradicted their stated academic goal of facilitating better computer education in UK schools, an environment that rightly demands open access to knowledge. Read more

Google Chrome 38 Beta Brings New Guest Mode and Easier Incognito Mode Switching

The developers have explained that the user switching feature has been redesigned and it will make changing profiles and into the incognito mode a lot simple. They have also added a new experimental Guest mode, a new experimental UI for Chrome supervised users has been implemented, and numerous under-the-hood changes have been made for stability and performance. "This release adds support for the new element thanks to the hard work of community contributor Yoav Weiss, who was able to dedicate his time to implementing this feature in multiple rendering engines because of a successful crowd-funding campaign that raised more than 50% of its funding goal." Read more

PfSense 2.1.5 Is a Free and Powerful FreeBSD-Based Firewall Operating System

PfSense is a free network firewall distribution based on the FreeBSD, it comes with a custom kernel, and a few quite powerful applications that should make its users’ life a lot easier. Most of the firewall distros are Linux-based, but PfSense is a little bit different and is using FreeBSD. Regular users won't feel anything out of the ordinary, but it's an interesting choice for the base. The developers of PfSense are also saying that their distro has been successful in replacing a number of commercial firewalls such as Check Point, Cisco PIX, Cisco ASA, Juniper, Sonicwall, Netgear, Watchguard, Astar, and others. Read more