Original image

Search of the Internet Reveals No Evidence of Time Travelers

Original image

Sorry, time travel enthusiasts: A recent study conducted by researchers at Michigan Technological University’s Department of Physics searched the Internet for signs of prescient content and found nothing. “The discovery of time travel into the past could be transformative not only to physics but to humanity,” study authors Robert Nemiroff and Teresa Wilson note in the paper. “This is perhaps the most comprehensive search to date.” Here’s how they came to their conclusion—and why there might still be hope.

Search Engines and Social Media

The first step was figuring out who they weren’t looking for. Nemiroff and Wilson ruled out looking for travelers who came from the past to the future for two reasons: The technology to create a time machine didn’t exist in the past and because “we were unable to conceive of a simple method that would clearly indicate that informational traces they might have left were evidence of time travel from the past and not just simple knowledge of the past.”

Having eliminated time travelers from the past from their Internet search, Nemiroff and Wilson had to determine how to best look for travelers from the future who might have left content that was once prescient. They decided to look for content between January 2006 and September 2013 using two search terms that originated during that time period, were sufficiently unique, and would still be well known and important in the future. The terms they settled on were Comet ISON, which was discovered on September 21, 2012, and Pope Francis, who was elected on March 16, 2013, and was the first pope to choose the name Francis. The researchers believed that there would be very little reason for anyone without prescient knowledge to be using those terms before they entered the popular lexicon. And because the use of hashtags is widespread and makes information easier to find, the researchers included the hashtags “#cometison” (but not #comet and #ison, which would not have returned information about just Comet ISON) and “#popefrancis” in their searches.

Nemiroff and Wilson first turned to search engines to look for evidence of time travelers. But Google turned out to be unreliable; recent advertisements on older news stories returned many results that, at first glance, appeared to be prescient. Bing, meanwhile, “did not appear to have a sufficient ability to filter results by posting dating to be useful,” the paper notes. Facebook and Google-Plus also weren't useful: Facebook allows the backdating of posts, and Google-Plus didn’t always sort search results chronologically, which made it difficult to dig up potentially prescient content.

The team then turned to Twitter, which had a number of advantages: The microblogging platform sorts searches chronologically and doesn’t allow backdating. They looked for their terms using Twitter’s own search, which enabled them to look all the way back to 2006 (when the service was created) and via the Topsy, a Twitter search service. Unfortunately,

No clearly prescient content involving “Comet ISON,” “#cometison,” “Pope Francis,” or “#popefrancis” was found from any Twitter tweet—ever. … Each of these search terms occurred numerous times—hundreds for Comet ISON and thousands for Pope Francis—but, with one noted exception, only after 2012 September for Comet ISON and 2013 March for Pope Francis.

That one exception the researchers mention was a blog that involved speculative discussion of “Pope Francis” that was advertised in a tweet, but the researchers concluded that the tweet and blog were not prescient.

Searching the Searches

Nemiroff and Wilson also looked for prescient queries on Internet search engines. “A time traveler … might have searched for a prescient term to see whether a given event was yet to occur,” they write. “We searched online databases for potentially prescient search terms themselves.”

A search of Google Trends revealed a number of searches, but the team didn’t consider them early enough to be prescient. Still, they don’t consider their results reliable, because Google Trends only reported back on terms with a large search volume. According to Google Trends, for example, there were no instances of “#cometison” ever being searched for, but during a manual search, the researchers did uncover some instances of that term being used. What’s more,

Google Trends only reported on the prevalence of searches as normalized to the largest search volume the desired time window, and not in absolute terms. … Search terms “Comet ISON” reported a zero score for all days from January 2004 through September 2012, the month that Comet ISON was discovered, but numerous search queries thereafter. This zero score, however, was normalized to the peak score set to 100 for 2013 March. The raw numbers of searches for March 2013 were not revealed by Google Trends. Therefore, to our understanding, the zero score really meant "less than 0.5 percent of the March 2013 value", which could well be greater than zero. Quite possibly, a single prescient search for Comet ISON would not have been recorded.

The team also searched the search engine of NASA’s Astronomy Picture of the Day website, during which a handful of results returned for ISON—but all appeared to be misspellings or “extraneous information.”

Emailing the Evidence

The researchers used one last test to tease our time travelers: They asked them to reveal themselves. In September 2013, Nemiroff and Wilson created a post online that asked time travelers to either tweet or email two hashtags—"#ICanChangeThePast2" or "#ICannotChangethePast2"—before August 2013.

A message incorporating the hashtagged term "#ICannotChangeThePast2" would indicate that time travel to the past is possibile but that the time traveler believes that they do not have the ability to alter the authors' past. ... Conversely, a message incorporating "ICanChangeThePast2" would indicate that time travel to the past is possible and that the time traveler can demonstrate the ability to alter the authors' past.

Asking the time travelers whether or not they could change the past would help the researchers determine what theories of time travel might hold water (the Novikov Self-Consistency Conjecture, which holds that history is fixed, or plastic time, in which history can be changed, leading to things like the Grandfather paradox).

Unfortunately, no instance of either of these hashtags appeared before August 2013, and none appeared in September 2013, either. The researchers didn't receive any emails that provided evidence of time travelers.

But there’s still hope…

Nemiroff and Wilson's search for prescient content turned up nothing, but they say that's no reason to give up hope. Changes to the NASA APOD search engine could have rendered their search incomplete, they note. Also, "although the negative results reported here may indicate that time travelers from the future are not among us and cannot communicate with us over the modern day Internet, they are by no means proof." The researchers might have missed traces either due to human error or because Internet catalogs were incomplete. What's more, time travelers might not be able to leave even informational traces, or it might be impossible to find anything left by them because it would violate "some yet-unknown law of physics." And what if time travelers don't want to be found?

You can read Nemiroff and Wilson's paper here.

Original image
Big Questions
How Long Could a Person Survive With an Unlimited Supply of Water, But No Food at All?
Original image

How long could a person survive if he had unlimited supply of water, but no food at all?

Richard Lee Fulgham:

I happen to know the answer because I have studied starvation, its course, and its utility in committing a painless suicide. (No, I’m not suicidal.)

A healthy human being can live approximately 45 to 65 days without food of any kind, so long as he or she keeps hydrated.

You could survive without any severe symptoms [for] about 30 to 35 days, but after that you would probably experience skin rashes, diarrhea, and of course substantial weight loss.

The body—as you must know—begins eating itself, beginning with adipose tissue (i.e. fat) and next the muscle tissue.

Google Mahatma Gandhi, who starved himself almost to death during 14 voluntary hunger strikes to bring attention to India’s independence movement.

Strangely, there is much evidence that starvation is a painless way to die. In fact, you experience a wonderful euphoria when the body realizes it is about to die. Whether this is a divine gift or merely secretions of the brain is not known.

Of course, the picture is not so pretty for all reports. Some victims of starvation have experienced extreme irritability, unbearably itchy skin rashes, unceasing diarrhea, painful swallowing, and edema.

In most cases, death comes when the organs begin to shut down after six to nine weeks. Usually the heart simply stops.

(Here is a detailed medical report of the longest known fast: 382 days.)

This post originally appeared on Quora. Click here to view.

Original image
NSF/LIGO/Sonoma State University/A. Simonnet
Astronomers Observe a New Kind of Massive Cosmic Collision for the First Time
Original image
NSF/LIGO/Sonoma State University/A. Simonnet

For the first time, astronomers have detected the colossal blast produced by the merger of two neutron stars—and they've recorded it both via the gravitational waves the event produced, as well as the flash of light it emitted.

Physicists believe that the pair of neutron stars—ultra-dense stars formed when a massive star collapses, following a supernova explosion—had been locked in a death spiral just before their final collision and merger. As they spiraled inward, a burst of gravitational waves was released; when they finally smashed together, high-energy electromagnetic radiation known as gamma rays were emitted. In the days that followed, electromagnetic radiation at many other wavelengths—X-rays, ultraviolet, optical, infrared, and radio waves—were released. (Imagine all the instruments in an orchestra, from the lowest bassoons to the highest piccolos, playing a short, loud note all at once.)

This is the first time such a collision has been observed, as well as the first time that both kinds of observations—gravitational waves and electromagnetic radiation—have been recorded from the same event, a feat that required co-operation among some 70 different observatories around the world, including ground-based observatories, orbiting telescopes, the U.S. LIGO (Laser Interferometer Gravitational-Wave Observatory), and European Virgo gravitational wave detectors.

"For me, it feels like the dawning of a next era in astrophysics," Julie McEnery, project scientist for NASA's Fermi Gamma-ray Space Telescope, one of the first instruments to record the burst of energy from the cosmic collision, tells Mental Floss. "With this observation, we've connected these new gravitational wave observations to the rest of the observations that we've been doing in astrophysics for a very long time."


The observations represent a breakthrough on several fronts. Until now, the only events detected via gravitational waves have been mergers of black holes; with these new results, it seems likely that gravitational wave technology—which is still in its infancy—will open many new phenomena to scientific scrutiny. At the same time, very little was known about the physics of neutron stars—especially their violent, final moments—until now. The observations are also shedding new light on the origin of gamma-ray bursts (GRBs)—extremely energetic explosions seen in distant galaxies. As well, the research may offer clues as to how the heavier elements, such as gold, platinum, and uranium, formed.

Astronomers around the world are thrilled by the latest findings, as today's flurry of excitement attests. The LIGO-Virgo results are being published today in the journal Physical Review Letters; further articles are due to be published in other journals, including Nature and Science, in the weeks ahead. Scientists also described the findings today at press briefings hosted by the National Science Foundation (the agency that funds LIGO) in Washington, and at the headquarters of the European Southern Observatory in Garching, Germany.

(Rumors of the breakthrough had been swirling for weeks; in August, astronomer J. Craig Wheeler of the University of Texas at Austin tweeted, "New LIGO. Source with optical counterpart. Blow your sox off!" He and another scientist who tweeted have since apologized for doing so prematurely, but this morning, minutes after the news officially broke, Wheeler tweeted, "Socks off!") 

The neutron star merger happened in a galaxy known as NGC 4993, located some 130 million light years from our own Milky Way, in the direction of the southern constellation Hydra.

Gravitational wave astronomy is barely a year and a half old. The first detection of gravitational waves—physicists describe them as ripples in space-time—came in fall 2015, when the signal from a pair of merging black holes was recorded by the LIGO detectors. The discovery was announced in February 2016 to great fanfare, and was honored with this year's Nobel Prize in Physics. Virgo, a European gravitational wave detector, went online in 2007 and was upgraded last year; together, they allow astronomers to accurately pin down the location of gravitational wave sources for the first time. The addition of Virgo also allows for a greater sensitivity than LIGO could achieve on its own.

LIGO previously recorded four different instances of colliding black holes—objects with masses between seven times the mass of the Sun and a bit less than 40 times the mass of the Sun. This new signal was weaker than that produced by the black holes, but also lasted longer, persisting for about 100 seconds; the data suggested the objects were too small to be black holes, but instead were neutron stars, with masses of about 1.1 and 1.6 times the Sun's mass. (In spite of their heft, neutron stars are tiny, with diameters of only a dozen or so miles.) Another key difference is that while black hole collisions can be detected only via gravitational waves—black holes are black, after all—neutron star collisions can actually be seen.


When the gravitational wave signal was recorded, on the morning of August 17, observatories around the world were notified and began scanning the sky in search of an optical counterpart. Even before the LIGO bulletin went out, however, the orbiting Fermi telescope, which can receive high-energy gamma rays from all directions in the sky at once, had caught something, receiving a signal less than two seconds after the gravitational wave signal tripped the LIGO detectors. This was presumed to be a gamma-ray burst, an explosion of gamma rays seen in deep space. Astronomers had recorded such bursts sporadically since the 1960s; however, their physical cause was never certain. Merging neutron stars had been a suggested culprit for at least some of these explosions.

"This is exactly what we'd hoped to see," says McEnery. "A gamma ray burst requires a colossal release of energy, and one of the hypotheses for what powers at least some of them—the ones that have durations of less than two seconds—was the merger of two neutron stars … We had hoped that we would see a gamma ray burst and a gravitational wave signal together, so it's fantastic to finally actually do this."

With preliminary data from LIGO and Virgo, combined with the Fermi data, scientists could tell with reasonable precision what direction in the sky the signal had come from—and dozens of telescopes at observatories around the world, including the U.S. Gemini telescopes, the European Very Large Telescope, and the Hubble Space Telescope, were quickly re-aimed toward Hydra, in the direction of reported signal.

The telescopes at the Las Campanas Observatory in Chile were well-placed for getting a first look—because the bulletin arrived in the morning, however, they had to wait until the sun dropped below the horizon.

"We had about eight to 10 hours, until sunset in Chile, to prepare for this," Maria Drout, an astronomer at the Carnegie Observatories in in Pasadena, California, which runs the Las Campanas telescopes, tells Mental Floss. She was connected by Skype to the astronomers in the control rooms of three different telescopes at Las Campanas, as they prepared to train their telescopes at the target region. "Usually you prepare a month in advance for an observing run on these telescopes, but this was all happening in a few hours," Drout says. She and her colleagues prepared a target list of about 100 galaxies, but less than one-tenth of the way through the list, by luck, they found it: a tiny blip of light in NGC 4993 that wasn't visible on archival images of the same galaxy. (It was the 1-meter Swope telescope that snagged the first images.)


When a new star-like object in a distant galaxy is spotted, a typical first guess is that it's a supernova (an exploding star). But this new object was changing very rapidly, growing 100 times dimmer over just a few days while also quickly becoming redder—which supernovae don't do, explains Drout, who is cross-appointed at the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto. "We ended up following it for three weeks or so, and by the end, it was very clear that this [neutron star merger] was what we were looking at," she says.

The researchers say they can't be sure if the resulting object was another, larger neutron star, or whether it would have been so massive that it would have collapsed into a black hole.

As exciting as the original detection of gravitational waves last year was, Drout is looking forward to a new era in which both gravitational waves and traditional telescopes can be used to study the same objects. "We can learn a lot more about these types of extreme systems that exist in the universe, by coupling the two together," she says.

The detection shows that "gravitational wave science is moving from being a physics experiment to being a tool for astronomers," Marcia Rieke, an astronomer at the University of Arizona who is not involved in the current research, tells Mental Floss. "So I think it's a pretty big deal."

Physicists are also learning something new about the origin of the heaviest elements in the periodic table. For many years, these were thought to arise from supernova explosions, but spectroscopic data from the newly observed neutron star merger (in which light is broken up into its component colors) suggests that such explosion produce enormous quantities of heavy elements—including enough gold to put Fort Knox to shame. (The blast is believed to have created some 200 Earth-masses of gold, the scientists say.) "It's telling us that most of the gold that we know about is produced in these mergers, and not in supernovae," McEnery says.

Editor's note: This post has been updated.


More from mental floss studios