Self-Motivation
David Goggins
Former Navy Seal
Career Development
Bryan Cranston
Actor
Critical Thinking
Liv Boeree
International Poker Champion
Emotional Intelligence
Amaryllis Fox
Former CIA Clandestine Operative
Management
Chris Hadfield
Retired Canadian Astronaut & Author
Learn
from the world's big
thinkers
Start Learning

Time Travel is Possible. Einstein Taught Us That.

Is the time we experience in our day-to-day lives real? Theoretical physicist Brian Greene explores the potential particles of time and why we could, in theory, travel forward in time but not back.

Brian Greene: We know a lot about time. We know that time in some sense is, at rock bottom, that which allows change to take place, right. When we say that time has elapsed, we notice that because things now are different from how they were a little while ago. That’s what we mean by time elapsing. But is time some fundamental quality of reality or is it something that our brains impose on our perceptions to organize our experience into some coherent framework that allows us to survive? I mean I can well imagine that we have been under evolutionary pressure over the millennia to organize perception so that we can survive, get the next meal, plan for the future. All of that would seemingly require that we have a conception of time that we apply to what we experience out there. But that doesn’t mean time as we experience it is real. It doesn’t mean that time as we experience it is how the world is actually structured. I mean there are many ideas that people put forward. The possibility, for instance, that, you know, we all know that matter is made of molecules and atoms. Could it be that time is also made of some kind of ingredient? A molecule of time? An atom of time? Is that really what time is at a fundamental level?

Time travel is absolutely possible. And this is not some sort of weird sci-fi thing that I’m talking about here. Albert Einstein taught us more than 100 years ago that time travel is possible if you’re focusing upon time travel to the future. And I’m not referring to the silly thing that we all age, right. We’re all going into the future. Sure, I’m talking about if you wanted to leapfrog into the future, if you wanted to see what the Earth will be like a million years from now, Albert Einstein told us how to do that. In fact, he told us two ways of how to do it. You can build a spaceship, go out into space near the speed of light, turn around and come back. Imagine you go out for six months and you turn around and you come back for six months. You will be one year older. But he taught us that your time is elapsing much slower than time back on Earth. So when you step out of your ship, you’re one year older, but Earth has gone through many, many years. It can have gone through 10,000, 100,000, or a million years depending on how close to the speed of light you traveled. 

And he also taught us if you go and hang out near the edge of a black hole, time again will elapse more slowly for you at the edge of the black hole than back on Earth. So you hang out there for a while, you come back and again you get out of your ship and it will be any number of years into the future, whatever you want all depending on how close you got to the edge of the black hole and how long you hung out there. That is time travel to the future. Now, of course, what people really want to know about is getting back. Can you travel back to the past? I don’t think so. We don’t know for sure. No one has given a definitive proof that you can’t travel to the past. In fact, some very reputable scientists have suggested ways that you might travel to the past. But every time we look at the proposals in detail, it seems kind of clear that they’re right at the edge of the known laws of physics. And most of us feel that when physics progresses to a point that we understand things even better, these proposals just will be ruled out, they won’t work. But I guess I would say there’s a long-shot possibility based on what we know today that time travel to the past might be possible. But most of us wouldn’t bet our life on it.

Theoretical physicist Brian Greene is fascinated by time. Is the time we experience in our day-to-day lives real? Is our interpretation of time actually how the world is structured? Could time be broken up into particles like matter? These questions fuel Greene's curiosity, and their most likely answers indicate that time travel into the future is very much possible. But traveling back in time, well, probably not. Greene explains why.


Brian Greene is the chairman of the World Science Festival, running May 27-31 in New York City.

Remote learning vs. online instruction: How COVID-19 woke America up to the difference

Educators and administrators must build new supports for faculty and student success in a world where the classroom might become virtual in the blink of an eye.

Credit: Shutterstock
Sponsored by Charles Koch Foundation
  • If you or someone you know is attending school remotely, you are more than likely learning through emergency remote instruction, which is not the same as online learning, write Rich DeMillo and Steve Harmon.
  • Education institutions must properly define and understand the difference between a course that is designed from inception to be taught in an online format and a course that has been rapidly converted to be offered to remote students.
  • In a future involving more online instruction than any of us ever imagined, it will be crucial to meticulously design factors like learner navigation, interactive recordings, feedback loops, exams and office hours in order to maximize learning potential within the virtual environment.
Keep reading Show less

White dwarfs hold key to life in the universe, suggests study

New study shows white dwarf stars create an essential component of life.

NASA and H. Richer (University of British Columbia)
Surprising Science
  • White dwarf stars create carbon atoms in the Milky Way galaxy, shows new study.
  • Carbon is an essential component of life.
  • White dwarfs make carbon in their hot insides before the stars die.
Keep reading Show less

"Forced empathy" is a powerful negotiation tool. Here's how to do it.

Master negotiator Chris Voss breaks down how to get what you want during negotiations.

Photo by Joe Raedle/Getty Images
Personal Growth
  • Former FBI negotiator Chris Voss explains how forced empathy is a powerful negotiating tactic.
  • The key is starting a sentence with "What" or "How," causing the other person to look at the situation through your eyes.
  • What appears to signal weakness is turned into a strength when using this tactic.
Keep reading Show less

Octopus-like creatures inhabit Jupiter’s moon, claims space scientist

A leading British space scientist thinks there is life under the ice sheets of Europa.

Credit: NASA/JPL-Caltech/SETI Institute
Surprising Science
  • A British scientist named Professor Monica Grady recently came out in support of extraterrestrial life on Europa.
  • Europa, the sixth largest moon in the solar system, may have favorable conditions for life under its miles of ice.
  • The moon is one of Jupiter's 79.
Keep reading Show less

How to catch a glimpse of Comet NEOWISE before it’s gone

Unless you plan to try again in 6,800 years, this week is your shot.

Image source: Sven Brandsma/Unsplash
Surprising Science
  • Comet NEOWISE will be most visible in the U.S. during the evenings from July 14-19, 2020.
  • After July 23rd, NEOWISE will be visible only through good binoculars and telescopes.
  • Look in the northwestern sky below the Big Dipper after dusk while there's a chance.

UPDATE: NASA is broadcasting a NASA Science Live episode highlighting Comet NEOWISE. NASA experts will discuss and answer public questions beginning at 3PM EST on Wednesday, July 15. Tune in via the agency's website, Facebook Live, YouTube, Periscope, LinkedIn, Twitch, or USTREAM.

Before last evening, July 14, 2020, the easiest way to see Comet NEOWISE — the brightest comet to zoom past Earth since 1977's Comet Hale-Bopp — from the United States was to catch it about an hour before sunrise. Now, however, you can see it in the evening, where it will remain for until the 19th. This is a definite don't-miss event — NEOWISE won't be coming back our way for another 6,800 years. It's the first major comet of the millennium, and by all accounts, it's unforgettable.

NEOWISE just got back from the Sun

Comet NEOWISE is named after the NASA infrared space telescope that first spotted it on March 27th. Its official moniker is C/2020 F3. It's estimated that the icy comet is about three miles across, not counting its tail.

NEOWISE is now heading away from our Sun, having made it closet approach, 27.4 million miles, to our star on July 3. The heat from that encounter is what's given NEOWISE its tail: It caused gas and dust to be released from the icy object, creating the tail of debris that looks so magical from here.

As NEOWISE moves closer to Earth, paradoxically, it will be less and less visible. By about July 23rd, you'll need binoculars or a telescope to see it at all. All of which makes this week prime time.

An evening delight

star constellation in sky

Image source: Allexxandar/Shutterstock/Big Think

First, find an unobstructed view of the northwest sky, free of streetlights, car headlights, apartment lights, and so on. And then, according to Sky & Telescope:

"Start looking about one hour after sunset, when you'll find it just over the northwestern horizon as the last of twilight fades into darkness."

It should be easy to spot since it's near to one of the most recognizable constellations up there, the Big Dipper. "Look about three fists below the bottom of the Big Dipper, which is hanging down by its handle high above, and from there perhaps a little to the right." Et voilà: Comet NEOWISE.

Says Sky & Telescope's Diana Hannikainen, "Look for a faint, fuzzy little 'star' with a fainter, fuzzier little tail extending upward from it."

The comet should be visible with the naked eye, though binoculars and a simple telescope may reveal more detail.

You may also be able to snap a photo of this special visitor, though you'll need the right gear to do so. A dedicated camera is more likely to capture a good shot than a telephone, but in either case, you'll need a tripod or some other means of holding the camera dead still as it takes a timed exposure of several seconds (not all phones can do this).

Quantcast