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Can we time travel? A theoretical physicist provides some answers – Phys.org

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Our curiosity about time travel is thousands of years old. Credit: Shutterstock

Time travel makes regular appearances in popular culture, with innumerable time travel storylines in movies, television and literature. But it is a surprisingly old idea: one can argue that the Greek tragedy Oedipus Rex, written by Sophocles over 2,500 years ago, is the first time travel story.

But is in fact possible? Given the popularity of the concept, this is a legitimate question. As a , I find that there are several possible answers to this question, not all of which are contradictory.

The simplest answer is that time travel cannot be possible because if it was, we would already be doing it. One can argue that it is forbidden by the , like the or relativity. There are also technical challenges: it might be possible but would involve vast amounts of energy.

There is also the matter of time-travel paradoxes; we can—hypothetically—resolve these if free will is an illusion, if many worlds exist or if the past can only be witnessed but not experienced. Perhaps time travel is impossible simply because time must flow in a linear manner and we have no control over it, or perhaps time is an illusion and time travel is irrelevant.

Laws of physics

Since Albert Einstein’s theory of relativity—which describes the nature of time, space and gravity—is our most profound theory of time, we would like to think that time travel is forbidden by relativity. Unfortunately, one of his colleagues from the Institute of Advanced Study, Kurt Gödel, invented a universe in which time travel was not just possible, but the past and future were inextricably tangled.

We can actually design time machines, but most of these (in principle) successful proposals require negative energy, or negative mass, which does not seem to exist in our universe. If you drop a tennis ball of negative mass, it will fall upwards. This argument is rather unsatisfactory, since it explains why we cannot time travel in practice only by involving another idea—that of negative energy or mass—that we do not really understand.

Mathematical physicist Frank Tipler conceptualized a time machine that does not involve negative mass, but requires more energy than exists in the universe.

Time travel also violates the second law of thermodynamics, which states that entropy or randomness must always increase. Time can only move in one direction—in other words, you cannot unscramble an egg. More specifically, by traveling into the past we are going from now (a high entropy state) into the past, which must have lower entropy.

This argument originated with the English cosmologist Arthur Eddington, and is at best incomplete. Perhaps it stops you traveling into the past, but it says nothing about time travel into the future. In practice, it is just as hard for me to travel to next Thursday as it is to travel to last Thursday.

Resolving paradoxes

There is no doubt that if we could time travel freely, we run into the paradoxes. The best known is the “grandfather paradox”: one could hypothetically use a to travel to the past and murder their grandfather before their father’s conception, thereby eliminating the possibility of their own birth. Logically, you cannot both exist and not exist.

Kurt Vonnegut’s anti-war novel “Slaughterhouse-Five,” published in 1969, describes how to evade the grandfather paradox. If free will simply does not exist, it is not possible to kill one’s grandfather in the past, since he was not killed in the past. The novel’s protagonist, Billy Pilgrim, can only travel to other points on his world line (the timeline he exists in), but not to any other point in space-time, so he could not even contemplate killing his grandfather.

The universe in “Slaughterhouse-Five” is consistent with everything we know. The second law of thermodynamics works perfectly well within it and there is no conflict with relativity. But it is inconsistent with some things we believe in, like free will—you can observe the past, like watching a movie, but you cannot interfere with the actions of people in it.

Could we allow for actual modifications of the past, so that we could go back and murder our grandfather—or Hitler? There are several multiverse theories that suppose that there are many timelines for different universes. This is also an old idea: in Charles Dickens’ “A Christmas Carol,” Ebeneezer Scrooge experiences two alternative timelines, one of which leads to a shameful death and the other to happiness.

Time is a river

Greek emperor Marcus Aurelius wrote that: “Time is like a river made up of the events which happen, and a violent stream; for as soon as a thing has been seen, it is carried away, and another comes in its place, and this will be carried away too.”

We can imagine that time does flow past every point in the universe, like a river around a rock. But it is difficult to make the idea precise. A flow is a rate of change—the flow of a river is the amount of water that passes a specific length in a given time. Hence if time is a flow, it is at the rate of one second per second, which is not a very useful insight.

Theoretical physicist Stephen Hawking suggested that a “chronology protection conjecture” must exist, an as-yet-unknown physical principle that forbids time travel. Hawking’s concept originates from the idea that we cannot know what goes on inside a black hole, because we cannot get information out of it. But this argument is redundant: we cannot time travel because we cannot time travel!

Researchers are investigating a more fundamental theory, where time and space “emerge” from something else. This is referred to as quantum gravity, but unfortunately it does not exist yet.

So is time travel possible? Probably not, but we don’t know for sure!

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Time travel could be possible, but only with parallel timelines

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Slack researcher discusses the fear, loathing and excitement surrounding AI in the workplace

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October 21, 2024

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SAN FRANCISCO (AP) — Artificial intelligence‘s recent rise to the forefront of business has left most office workers wondering how often they should use the technology and whether a computer will eventually replace them.

Those were among the highlights of a recent study conducted by the workplace communications platform Slack. After conducting in-depth interviews with 5,000 desktop workers, Slack concluded there are five types of AI personalities in the workplace: “The Maximalist” who regularly uses AI on their jobs; “The Underground” who covertly uses AI; “The Rebel,” who abhors AI; “The Superfan” who is excited about AI but still hasn’t used it; and “The Observer” who is taking a wait-and-see approach.

Only 50% of the respondents fell under the Maximalist or Underground categories, posing a challenge for businesses that want their workers to embrace AI technology. The Associated Press recently discussed the excitement and tension surrounding AI at work with Christina Janzer, Slack’s senior vice president of research and analytics.

Q: What do you make about the wide range of perceptions about AI at work?

A: It shows people are experiencing AI in very different ways, so they have very different emotions about it. Understanding those emotions will help understand what is going to drive usage of AI. If people are feeling guilty or nervous about it, they are not going to use it. So we have to understand where people are, then point them toward learning to value this new technology.

Q: The Maximalist and The Underground both seem to be early adopters of AI at work, but what is different about their attitudes?

A: Maximalists are all in on AI. They are getting value out of it, they are excited about it, and they are actively sharing that they are using it, which is a really big driver for usage among others.

The Underground is the one that is really interesting to me because they are using it, but they are hiding it. There are different reasons for that. They are worried they are going to be seen as incompetent. They are worried that AI is going to be seen as cheating. And so with them, we have an opportunity to provide clear guidelines to help them know that AI usage is celebrated and encouraged. But right now they don’t have guidelines from their companies and they don’t feel particularly encouraged to use it.

Overall, there is more excitement about AI than not, so I think that’s great We just need to figure out how to harness that.

Q: What about the 19% of workers who fell under the Rebel description in Slack’s study?

A: Rebels tend to be women, which is really interesting. Three out of five rebels are women, which I obviously don’t like to see. Also, rebels tend to be older. At a high level, men are adopting the technology at higher rates than women.

Q: Why do you think more women than men are resisting AI?

A: Women are more likely to see AI as a threat, more likely to worry that AI is going to take over their jobs. To me, that points to women not feeling as trusted in the workplace as men do. If you feel trusted by your manager, you are more likely to experiment with AI. Women are reluctant to adopt a technology that might be seen as a replacement for them whereas men may have more confidence that isn’t going to happen because they feel more trusted.

Q: What are some of the things employers should be doing if they want their workers to embrace AI on the job?

A: We are seeing three out of five desk workers don’t even have clear guidelines with AI, because their companies just aren’t telling them anything, so that’s a huge opportunity.

Another opportunity to encourage AI usage in the open. If we can create a culture where it’s celebrated, where people can see the way people are using it, then they can know that it’s accepted and celebrated. Then they can be inspired.

The third thing is we have to create a culture of experimentation where people feel comfortable trying it out, testing it, getting comfortable with it because a lot of people just don’t know where to start. The reality is you can start small, you don’t have to completely change your job. Having AI write an email or summarize content is a great place to start so you can start to understand what this technology can do.

Q: Do you think the fears about people losing their jobs because of AI are warranted?

A: People with AI are going to replace people without AI.

The Canadian Press. All rights reserved.

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Biden administration to provide $325 million for new Michigan semiconductor factory

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October 21, 2024

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WASHINGTON (AP) — The Biden administration said Tuesday that it would provide up to $325 million to Hemlock Semiconductor for a new factory, a move that could help give Democrats a political edge in the swing state of Michigan ahead of election day.

The funding would support 180 manufacturing jobs in Saginaw County, where Republicans and Democrats were neck-in-neck for the past two presidential elections. There would also be construction jobs tied to the factory that would produce hyper-pure polysilicon, a building block for electronics and solar panels, among other technologies.

Commerce Secretary Gina Raimondo said on a call with reporters that the funding came from the CHIPS and Science Act, which President Joe Biden signed into law in 2022. It’s part of a broader industrial strategy that the campaign of Vice President Kamala Harris, the Democratic nominee, supports, while Republican nominee Donald Trump, the former president, sees tariff hikes and income tax cuts as better to support manufacturing.

“What we’ve been able to do with the CHIPS Act is not just build a few new factories, but fundamentally revitalize the semiconductor ecosystem in our country with American workers,” Raimondo said. “All of this is because of the vision of the Biden-Harris administration.”

A senior administration official said the timing of the announcement reflected the negotiating process for reaching terms on the grant, rather than any political considerations. The official insisted on anonymity to discuss the process.

After site work, Hemlock Semiconductor plans to begin construction in 2026 and then start production in 2028, the official said.

Running in 2016, Trump narrowly won Saginaw County and Michigan as a whole. But in 2020 against Biden, both Saginaw County and Michigan flipped to the Democrats.

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The Internet is Littered in ‘Educated Guesses’ Without the ‘Education’

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October 8, 2024

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Although no one likes a know-it-all, they dominate the Internet.

The Internet began as a vast repository of information. It quickly became a breeding ground for self-proclaimed experts seeking what most people desire: recognition and money.

Today, anyone with an Internet connection and some typing skills can position themselves, regardless of their education or experience, as a subject matter expert (SME). From relationship advice, career coaching, and health and nutrition tips to citizen journalists practicing pseudo-journalism, the Internet is awash with individuals—Internet talking heads—sharing their “insights,” which are, in large part, essentially educated guesses without the education or experience.

The Internet has become a 24/7/365 sitcom where armchair experts think they’re the star.

Not long ago, years, sometimes decades, of dedicated work and acquiring education in one’s field was once required to be recognized as an expert. The knowledge and opinions of doctors, scientists, historians, et al. were respected due to their education and experience. Today, a social media account and a knack for hyperbole are all it takes to present oneself as an “expert” to achieve Internet fame that can be monetized.

On the Internet, nearly every piece of content is self-serving in some way.

The line between actual expertise and self-professed knowledge has become blurry as an out-of-focus selfie. Inadvertently, social media platforms have created an informal degree program where likes and shares are equivalent to degrees. After reading selective articles, they’ve found via and watching some TikTok videos, a person can post a video claiming they’re an herbal medicine expert. Their new “knowledge,” which their followers will absorb, claims that Panda dung tea—one of the most expensive teas in the world and isn’t what its name implies—cures everything from hypertension to existential crisis. Meanwhile, registered dietitians are shaking their heads, wondering how to compete against all the misinformation their clients are exposed to.

More disturbing are individuals obsessed with evangelizing their beliefs or conspiracy theories. These people write in-depth blog posts, such as Elvis Is Alive and the Moon Landings Were Staged, with links to obscure YouTube videos, websites, social media accounts, and blogs. Regardless of your beliefs, someone or a group on the Internet shares them, thus confirming your beliefs.

Misinformation is the Internet’s currency used to get likes, shares, and engagement; thus, it often spreads like a cosmic joke. Consider the prevalence of clickbait headlines:

  • You Won’t Believe What Taylor Swift Says About Climate Change!
  • This Bedtime Drink Melts Belly Fat While You Sleep!
  • In One Week, I Turned $10 Into $1 Million!

Titles that make outrageous claims are how the content creator gets reads and views, which generates revenue via affiliate marketing, product placement, and pay-per-click (PPC) ads. Clickbait headlines are how you end up watching a TikTok video by a purported nutrition expert adamantly asserting you can lose belly fat while you sleep by drinking, for 14 consecutive days, a concoction of raw eggs, cinnamon, and apple cider vinegar 15 minutes before going to bed.

Our constant search for answers that’ll explain our convoluted world and our desire for shortcuts to success is how Internet talking heads achieve influencer status. Because we tend to seek low-hanging fruits, we listen to those with little experience or knowledge of the topics they discuss yet are astute enough to know what most people want to hear.

There’s a trend, more disturbing than spreading misinformation, that needs to be called out: individuals who’ve never achieved significant wealth or traded stocks giving how-to-make-easy-money advice, the appeal of which is undeniable. Several people I know have lost substantial money by following the “advice” of Internet talking heads.

Anyone on social media claiming to have a foolproof money-making strategy is lying. They wouldn’t be peddling their money-making strategy if they could make easy money.

Successful people tend to be secretive.

Social media companies design their respective algorithms to serve their advertisers—their source of revenue—interest; hence, content from Internet talking heads appears most prominent in your feeds. When a video of a self-professed expert goes viral, likely because it pressed an emotional button, the more people see it, the more engagement it receives, such as likes, shares and comments, creating a cycle akin to a tornado.

Imagine scrolling through your TikTok feed and stumbling upon a “scientist” who claims they can predict the weather using only aluminum foil, copper wire, sea salt and baking soda. You chuckle, but you notice his video got over 7,000 likes, has been shared over 600 times and received over 400 comments. You think to yourself, “Maybe this guy is onto something.” What started as a quest to achieve Internet fame evolved into an Internet-wide belief that weather forecasting can be as easy as DIY crafts.

Since anyone can call themselves “an expert,” you must cultivate critical thinking skills to distinguish genuine expertise from self-professed experts’ self-promoting nonsense. While the absurdity of the Internet can be entertaining, misinformation has serious consequences. The next time you read a headline that sounds too good to be true, it’s probably an Internet talking head making an educated guess; without the education seeking Internet fame, they can monetize.

______________________________________________________________

 

Nick Kossovan, a self-described connoisseur of human psychology, writes about what’s

on his mind from Toronto. You can follow Nick on Twitter and Instagram @NKossovan.

 

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