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.

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Maps show how CNN lost America to Fox News

Is this proof of a dramatic shift?

Strange Maps
  • Map details dramatic shift from CNN to Fox News over 10-year period
  • Does it show the triumph of "fake news" — or, rather, its defeat?
  • A closer look at the map's legend allows for more complex analyses

Dramatic and misleading

Image: Reddit / SICResearch

The situation today: CNN pushed back to the edges of the country.

Over the course of no more than a decade, America has radically switched favorites when it comes to cable news networks. As this sequence of maps showing TMAs (Television Market Areas) suggests, CNN is out, Fox News is in.

The maps are certainly dramatic, but also a bit misleading. They nevertheless provide some insight into the state of journalism and the public's attitudes toward the press in the US.

Let's zoom in:

  • It's 2008, on the eve of the Obama Era. CNN (blue) dominates the cable news landscape across America. Fox News (red) is an upstart (°1996) with a few regional bastions in the South.
  • By 2010, Fox News has broken out of its southern heartland, colonizing markets in the Midwest and the Northwest — and even northern Maine and southern Alaska.
  • Two years later, Fox News has lost those two outliers, but has filled up in the middle: it now boasts two large, contiguous blocks in the southeast and northwest, almost touching.
  • In 2014, Fox News seems past its prime. The northwestern block has shrunk, the southeastern one has fragmented.
  • Energised by Trump's 2016 presidential campaign, Fox News is back with a vengeance. Not only have Maine and Alaska gone from entirely blue to entirely red, so has most of the rest of the U.S. Fox News has plugged the Nebraska Gap: it's no longer possible to walk from coast to coast across CNN territory.
  • By 2018, the fortunes from a decade earlier have almost reversed. Fox News rules the roost. CNN clings on to the Pacific Coast, New Mexico, Minnesota and parts of the Northeast — plus a smattering of metropolitan areas in the South and Midwest.

"Frightening map"

Image source: Reddit / SICResearch

This sequence of maps, showing America turning from blue to red, elicited strong reactions on the Reddit forum where it was published last week. For some, the takeover by Fox News illustrates the demise of all that's good and fair about news journalism. Among the comments?

  • "The end is near."
  • "The idiocracy grows."
  • "(It's) like a spreading disease."
  • "One of the more frightening maps I've seen."
For others, the maps are less about the rise of Fox News, and more about CNN's self-inflicted downward spiral:
  • "LOL that's what happens when you're fake news!"
  • "CNN went down the toilet on quality."
  • "A Minecraft YouTuber could beat CNN's numbers."
  • "CNN has become more like a high-school production of a news show."

Not a few find fault with both channels, even if not always to the same degree:

  • "That anybody considers either of those networks good news sources is troubling."
  • "Both leave you understanding less rather than more."
  • "This is what happens when you spout bullsh-- for two years straight. People find an alternative — even if it's just different bullsh--."
  • "CNN is sh-- but it's nowhere close to the outright bullsh-- and baseless propaganda Fox News spews."

"Old people learning to Google"

Image: Google Trends

CNN vs. Fox News search terms (200!-2018)

But what do the maps actually show? Created by SICResearch, they do show a huge evolution, but not of both cable news networks' audience size (i.e. Nielsen ratings). The dramatic shift is one in Google search trends. In other words, it shows how often people type in "CNN" or "Fox News" when surfing the web. And that does not necessarily reflect the relative popularity of both networks. As some commenters suggest:

  • "I can't remember the last time that I've searched for a news channel on Google. Is it really that difficult for people to type 'cnn.com'?"
  • "More than anything else, these maps show smart phone proliferation (among older people) more than anything else."
  • "This is a map of how old people and rural areas have learned to use Google in the last decade."
  • "This is basically a map of people who don't understand how the internet works, and it's no surprise that it leans conservative."

A visual image as strong as this map sequence looks designed to elicit a vehement response — and its lack of context offers viewers little new information to challenge their preconceptions. Like the news itself, cartography pretends to be objective, but always has an agenda of its own, even if just by the selection of its topics.

The trick is not to despair of maps (or news) but to get a good sense of the parameters that are in play. And, as is often the case (with both maps and news), what's left out is at least as significant as what's actually shown.

One important point: while Fox News is the sole major purveyor of news and opinion with a conservative/right-wing slant, CNN has more competition in the center/left part of the spectrum, notably from MSNBC.

Another: the average age of cable news viewers — whether they watch CNN or Fox News — is in the mid-60s. As a result of a shift in generational habits, TV viewing is down across the board. Younger people are more comfortable with a "cafeteria" approach to their news menu, selecting alternative and online sources for their information.

It should also be noted, however, that Fox News, according to Harvard's Nieman Lab, dominates Facebook when it comes to engagement among news outlets.

CNN, Fox and MSNBC

Image: Google Trends

CNN vs. Fox (without the 'News'; may include searches for actual foxes). See MSNBC (in yellow) for comparison

For the record, here are the Nielsen ratings for average daily viewer total for the three main cable news networks, for 2018 (compared to 2017):

  • Fox News: 1,425,000 (-5%)
  • MSNBC: 994,000 (+12%)
  • CNN: 706,000 (-9%)

And according to this recent overview, the top 50 of the most popular websites in the U.S. includes cnn.com in 28th place, and foxnews.com in... 27th place.

The top 5, in descending order, consists of google.com, youtube.com, facebook.com, amazon.com and yahoo.com — the latter being the highest-placed website in the News and Media category.
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