Time Travel Trivia and Some Spoilers

I love all things about time travel. I'd love to know it's possible to go back or forward in time, but science rarely points to either possibility. 

Science meets pop culture on StarTalk! with host astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life. 

The video embedded here hits on the type of time travel used in A Christmas Carol and whether Ebenezer Scrooge gets pulled through a wormhole.

How about considering how people thought about time travel before Einstein, and how the special theory of relativity changed how we think about time? 

Discover time dilation and how speed and gravity affect an object’s passage of time. And what about those pesky paradoxes of traveling and meddling with the past? 

So many questions!

Is there one immutable timeline or many timelines in a multiverse? Do we have free will? What is time to a photon traveling at the speed of light? How would we police time travel if it were possible? Will we even have time travel in the future? If time travel gets invented, why are we not overrun by tourists from the future? 

Which films depict time travel best? 

How are cells affected by time travel? 

Could we theoretically travel to before the Big Bang, because is there even a place to travel to before the Big Bang? 

When Black Holes Collide

That is not a headline I would think we would not want to see, but astronomers have detected the largest merger of two black holes to date via measuring gravitational waves. The collision produced a single black hole roughly 225 times the mass of the Sun.

A post at caltech.edu says that the signal, designated GW231123, was detected during the fourth observing run of the LVK network on November 23, 2023. I didn't feel a thing back then - or since.

These points in space, whose gravitational pull is so strong that nothing escapes (including light), form when very large stars run out of fuel in their cores. The object collapses in on itself, shrouding the core in an incredibly warped region of spacetime. That's why they are sometimes theorized to be a way to travel through time. At least, in science fiction tales, the idea of a wormhole works.

Being a time travel fan, I like this hypothetical structure that connects disparate points in spacetime. One way to visualize it is as a tunnel with two ends at separate points in spacetime (i.e., different locations, different points in time, or both). 

A wormhole visualized as a two-dimensional surface.
Route (a) is the shortest path through normal space between points 1 and 2.
Route (b) is a shorter path through a wormhole. 
Image: MikeRun, CC BY-SA 4.0, Link

Wormholes are based on a special solution of the Einstein field equations. It's not helpful to me but, more precisely, they are a transcendental bijection of the spacetime continuum, an asymptotic projection of the Calabi–Yau manifold manifesting itself in anti-de Sitter space.

The existence of black holes was first theorized by Einstein in 1916, predicted by his theory of general relativity. The theory posited that what we experience as gravity is actually the effect of mass curving space and time—in the case of black holes, it's curved to the point where light is effectively "stuck" inside.

The event horizon is the term for the boundary of a black hole beyond which light can't escape.

Black holes are probably fairly common on a universe level. Scientists estimate there are 40 quintillion (1 quintillion equals 1 billion billion) black holes in the universe, none of which can be seen directly. Instead, their effect on nearby objects reveals their presence, indicating properties like size and spin. The pull of black holes can cause nearby matter to superheat, emitting X-rays detected on Earth. This is how the presence of Cygnus X-1, the first confirmed black hole, was detected in 1964.

The first-ever "image" of a black hole was published in 2019 by the Event Horizon Telescope, capturing the light bent around the object. The black hole is located 50 million light-years away in the M87 galaxy.

9 Types of Paralell Universes

 I wrote a post about time travel and in researching the post I ended up delving into parallel universes as one possible way to time travel. 

Brian Greene, physicist and science writer, wrote The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos asking "Is our universe the only universe?" 

In the multiverse, there is a duplicate of every one of us. Greene discussed nine types of parallel universes. This is not simple.

The quilted multiverse conditions in an infinite universe necessarily repeat across space, yielding parallel worlds.

The inflationary multiverse says that eternal cosmological inflation yields an enormous network of bubble universes, of which our universe would be one.

The brane multiverse states that in M-theory, in the brane world scenario, our universe exists on one three-dimensional brane, which floats in a higher dimensional expanse potentially populated by other branes – other parallel universes.

The cyclic multiverse is saying that collisions between braneworlds can manifest as big bang-like beginnings, yielding universes that are parallel in time.

The landscape multiverse states that by combining inflationary cosmology and string theory, the many different shapes for string theory's extra dimensions give rise to many different bubble universes.

The quantum multiverse creates a new universe when a diversion in events occurs, as in the many-worlds interpretation of quantum mechanics.

The holographic multiverse is derived from the theory that the surface area of a space can simulate the volume of the region.

The simulated multiverse implies that technological leaps suggest that the universe is just a simulation.

The ultimate multiverse is the ultimate theory, saying the principle of fecundity asserts that every possible universe is a real universe, thereby obviating the question of why one possibility – ours – is special. These universes instantiate all possible mathematical equations.

What If You Gave a Party for Time Travellers and No One Showed Up?

I love the idea of time travel and all the theories of it and all the fiction that has been created about it. That giant of theoretical physics, cosmology, and pop culture, Stephen Hawking, once did a simple time travel experiment. He invited time travelers to a party.

It was held on a Sunday, June 29, 2009. Hawking had a nice party room set up with champagne and food at Gonville & Caius College, Cambridge, beneath a banner reading, “Welcome Time Travellers” and he waited.

The party invitations gave precise GPS coordinates for the travelers. Of course, Stephen did not send out any of the invitations until after the reception had passed. That was critical to the experimental design: Only those who could travel back in time would be able to attend.

No one showed up. There is a video of the party. Canapes uneaten, flutes filled with Krug champagne untouched, balloons decorating the place and Stephen sitting in his wheelchair under that banner.

Wouldn't any future time traveler have been excited to go back and party with Hawking? 

The invitation was included in his mini-series Into the Universe With Stephen Hawking and the Discovery TV crew filmed the event just in case someone did travel back. 

Some fancy invitations were auctioned off for charity and the party got a lot of press and exists all over the Internet. “I’m hoping copies of [the invitation], in one form or another, will survive for many thousands of years,” Hawking said, considering that maybe some future time traveler will see it and decide to show up to the party. Of course, that would create a whole new timeline in one of the many possible universes out there.

So why didn't any time travelers attend? I've seen a bunch of possible reasons posited.

1. We never do figure out how to time travel because it's not possible. A bummer reason for believers.
2. Maybe people in the future who had a way to time travel just never knew about Hawking's party.
3. Despite Hawking's wishes, the invites didn't survive to the time when time travel was invented.
4. Might Stephen had lied and they did show up but he kept it secret to protect the space-time continuum?
5. Perhaps you can only travel back to the point where time travel was invented.
6. Maybe the party didn't sound all that exciting and they decided to pass on this party.
7. The blog Giant Freakin Robot came up with some other possible reasons including that the party took place on a different reality timeline;
8. “time travelers are dicks” 
9. Even if people do figure out how to time travel, they may not have precise control like Doc Brown. "Ask Dr. Sam Beckett. Ask Billy Pilgrim. Ask Fry, Bender, and Professor Farnsworth who invented a time machine that only goes forward"
10. The darker version of #4 - "Hawking killed them all to preserve the time-space continuum.”

An earlier version of this post appeared on my blog Weekends in Paradelle

Time Machines

When I was in second grade, I saw the film The Time Machine at a drive-in theater. It was directed by George Pal, starred Rod Taylor, and was released in 1960. It was scary. It was cool. It had "primitive" special effects by today's standards. But I loved it.

Eventually, it sent me to the library to get the novel by H.G. Wells. Twenty years later, I taught that book to a bunch of like-minded seventh graders that I had lured into reading its very 19th century pages with very 21st century imaginings about traveling through time.

Then, the summer after fourth grade, I tried to build a time machine in my own basement. I had a "lab" in a old coal bin that was full of chemistry sets, rockets, rocks, any tool I could find, model car kits and salvaged electronic components.

I had no idea where to start or what to do, but I just went at it. (Years later, I would jealously watch ET do the same kind of thing successfully.) I have never lost my fascination for time travel.

Last May, artist Paul St George exhibited an outdoor interactive video installation linking London and New York City in a faux "telectroscope."

Unfortunately, I only found out about it after it was over.

Of course, it wasn't any more real than the ones from earlier centuries - but it "worked."

It had a fictional "back story" that said that the device worked by using a transatlantic tunnel started by the artist's fictional great-grandfather, Alexander Stanhope St. George. People looking in one end in NYC could see and hear those at the other end in London.

telectroscope photo via my Flickr friend urbanshoregirl

I like the term "distant seeing" that was attached to the invention and has remained.

The installation art actually used a visual high speed broadband link between London and New York City that did allow people to see across the ocean.

You can't really call any of these "television systems" or "time machines." And the term telectroscope was replaced by the term "television." But, looking back at the original 1870s imaginings, it sounds like they were describing television or the Internet - or some merging of the two that is in progress right now.




Go Deeper

• Paul St. George's Telectroscope Project
• http://en.wikipedia.org/wiki/Telectroscope
• The Telectroscope Project Blog
• BBC News video of the Telectroscope Project
• Telectroscope Video from New York City