Tech

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

Published

2 years ago

June 15, 2022

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 time travel in fact possible? Given the popularity of the concept, this is a legitimate question. As a theoretical physicist, 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 laws of physics, like the second law of thermodynamics 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 time machine 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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Tech

Ottawa orders TikTok’s Canadian arm to be dissolved

Published

3 days ago

November 6, 2024

Anne Joseph

The federal government is ordering the dissolution of TikTok’s Canadian business after a national security review of the Chinese company behind the social media platform, but stopped short of ordering people to stay off the app.

Industry Minister François-Philippe Champagne announced the government’s “wind up” demand Wednesday, saying it is meant to address “risks” related to ByteDance Ltd.’s establishment of TikTok Technology Canada Inc.

“The decision was based on the information and evidence collected over the course of the review and on the advice of Canada’s security and intelligence community and other government partners,” he said in a statement.

The announcement added that the government is not blocking Canadians’ access to the TikTok application or their ability to create content.

However, it urged people to “adopt good cybersecurity practices and assess the possible risks of using social media platforms and applications, including how their information is likely to be protected, managed, used and shared by foreign actors, as well as to be aware of which country’s laws apply.”

Champagne’s office did not immediately respond to a request for comment seeking details about what evidence led to the government’s dissolution demand, how long ByteDance has to comply and why the app is not being banned.

A TikTok spokesperson said in a statement that the shutdown of its Canadian offices will mean the loss of hundreds of well-paying local jobs.

“We will challenge this order in court,” the spokesperson said.

“The TikTok platform will remain available for creators to find an audience, explore new interests and for businesses to thrive.”

The federal Liberals ordered a national security review of TikTok in September 2023, but it was not public knowledge until The Canadian Press reported in March that it was investigating the company.

At the time, it said the review was based on the expansion of a business, which it said constituted the establishment of a new Canadian entity. It declined to provide any further details about what expansion it was reviewing.

A government database showed a notification of new business from TikTok in June 2023. It said Network Sense Ventures Ltd. in Toronto and Vancouver would engage in “marketing, advertising, and content/creator development activities in relation to the use of the TikTok app in Canada.”

Even before the review, ByteDance and TikTok were lightning rod for privacy and safety concerns because Chinese national security laws compel organizations in the country to assist with intelligence gathering.

Such concerns led the U.S. House of Representatives to pass a bill in March designed to ban TikTok unless its China-based owner sells its stake in the business.

Champagne’s office has maintained Canada’s review was not related to the U.S. bill, which has yet to pass.

Canada’s review was carried out through the Investment Canada Act, which allows the government to investigate any foreign investment with potential to might harm national security.

While cabinet can make investors sell parts of the business or shares, Champagne has said the act doesn’t allow him to disclose details of the review.

Wednesday’s dissolution order was made in accordance with the act.

The federal government banned TikTok from its mobile devices in February 2023 following the launch of an investigation into the company by federal and provincial privacy commissioners.

— With files from Anja Karadeglija in Ottawa

This report by The Canadian Press was first published Nov. 6, 2024.

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Health

Here is how to prepare your online accounts for when you die

Published

2 weeks ago

October 24, 2024

Anne Joseph

LONDON (AP) — Most people have accumulated a pile of data — selfies, emails, videos and more — on their social media and digital accounts over their lifetimes. What happens to it when we die?

It’s wise to draft a will spelling out who inherits your physical assets after you’re gone, but don’t forget to take care of your digital estate too. Friends and family might treasure files and posts you’ve left behind, but they could get lost in digital purgatory after you pass away unless you take some simple steps.

Here’s how you can prepare your digital life for your survivors:

Apple

The iPhone maker lets you nominate a “ legacy contact ” who can access your Apple account’s data after you die. The company says it’s a secure way to give trusted people access to photos, files and messages. To set it up you’ll need an Apple device with a fairly recent operating system — iPhones and iPads need iOS or iPadOS 15.2 and MacBooks needs macOS Monterey 12.1.

For iPhones, go to settings, tap Sign-in & Security and then Legacy Contact. You can name one or more people, and they don’t need an Apple ID or device.

You’ll have to share an access key with your contact. It can be a digital version sent electronically, or you can print a copy or save it as a screenshot or PDF.

Take note that there are some types of files you won’t be able to pass on — including digital rights-protected music, movies and passwords stored in Apple’s password manager. Legacy contacts can only access a deceased user’s account for three years before Apple deletes the account.

Google

Google takes a different approach with its Inactive Account Manager, which allows you to share your data with someone if it notices that you’ve stopped using your account.

When setting it up, you need to decide how long Google should wait — from three to 18 months — before considering your account inactive. Once that time is up, Google can notify up to 10 people.

You can write a message informing them you’ve stopped using the account, and, optionally, include a link to download your data. You can choose what types of data they can access — including emails, photos, calendar entries and YouTube videos.

There’s also an option to automatically delete your account after three months of inactivity, so your contacts will have to download any data before that deadline.

Facebook and Instagram

Some social media platforms can preserve accounts for people who have died so that friends and family can honor their memories.

When users of Facebook or Instagram die, parent company Meta says it can memorialize the account if it gets a “valid request” from a friend or family member. Requests can be submitted through an online form.

The social media company strongly recommends Facebook users add a legacy contact to look after their memorial accounts. Legacy contacts can do things like respond to new friend requests and update pinned posts, but they can’t read private messages or remove or alter previous posts. You can only choose one person, who also has to have a Facebook account.

You can also ask Facebook or Instagram to delete a deceased user’s account if you’re a close family member or an executor. You’ll need to send in documents like a death certificate.

TikTok

The video-sharing platform says that if a user has died, people can submit a request to memorialize the account through the settings menu. Go to the Report a Problem section, then Account and profile, then Manage account, where you can report a deceased user.

Once an account has been memorialized, it will be labeled “Remembering.” No one will be able to log into the account, which prevents anyone from editing the profile or using the account to post new content or send messages.

It’s not possible to nominate a legacy contact on Elon Musk’s social media site. But family members or an authorized person can submit a request to deactivate a deceased user’s account.

Passwords

Besides the major online services, you’ll probably have dozens if not hundreds of other digital accounts that your survivors might need to access. You could just write all your login credentials down in a notebook and put it somewhere safe. But making a physical copy presents its own vulnerabilities. What if you lose track of it? What if someone finds it?

Instead, consider a password manager that has an emergency access feature. Password managers are digital vaults that you can use to store all your credentials. Some, like Keeper,Bitwarden and NordPass, allow users to nominate one or more trusted contacts who can access their keys in case of an emergency such as a death.

But there are a few catches: Those contacts also need to use the same password manager and you might have to pay for the service.

___

Is there a tech challenge you need help figuring out? Write to us at onetechtip@ap.org with your questions.

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Tech

Google’s partnership with AI startup Anthropic faces a UK competition investigation

Published

2 weeks ago

October 24, 2024

Anne Joseph

LONDON (AP) — Britain’s competition watchdog said Thursday it’s opening a formal investigation into Google’s partnership with artificial intelligence startup Anthropic.

The Competition and Markets Authority said it has “sufficient information” to launch an initial probe after it sought input earlier this year on whether the deal would stifle competition.

The CMA has until Dec. 19 to decide whether to approve the deal or escalate its investigation.

“Google is committed to building the most open and innovative AI ecosystem in the world,” the company said. “Anthropic is free to use multiple cloud providers and does, and we don’t demand exclusive tech rights.”

San Francisco-based Anthropic was founded in 2021 by siblings Dario and Daniela Amodei, who previously worked at ChatGPT maker OpenAI. The company has focused on increasing the safety and reliability of AI models. Google reportedly agreed last year to make a multibillion-dollar investment in Anthropic, which has a popular chatbot named Claude.

Anthropic said it’s cooperating with the regulator and will provide “the complete picture about Google’s investment and our commercial collaboration.”

“We are an independent company and none of our strategic partnerships or investor relationships diminish the independence of our corporate governance or our freedom to partner with others,” it said in a statement.

The U.K. regulator has been scrutinizing a raft of AI deals as investment money floods into the industry to capitalize on the artificial intelligence boom. Last month it cleared Anthropic’s $4 billion deal with Amazon and it has also signed off on Microsoft’s deals with two other AI startups, Inflection and Mistral.

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