MATT STRASSLER
Of Particular Significance

Send Your Dog Through a Wormhole?

A wormhole! What an amazing concept — a secret tunnel that connects two different regions of space! Could real ones exist? Could we — or our dogs — travel through them, and visit other galaxies billions of light years away, and come back to tell everyone all about it?

I bring up dogs because of a comment, quoted in the Guardian and elsewhere, by my friend and colleague, experimentalist Maria Spiropulu. Spiropulu is a senior author on the wormhole-related paper that has gotten so much attention in the past week, and she was explaining what it was all about.

  • “People come to me and they ask me, ‘Can you put your dog in the wormhole?’ So, no,” Spiropulu told reporters during a video briefing. “… That’s a huge leap.”

For this, I can’t resist teasing Spiropulu a little. She’s done many years of important work at the Large Hadron Collider and previously at the Tevatron, before taking on quantum computing and the simulation of wormholes. But, oh my! The idea that this kind of research could ever lead to a wormhole that a dog could traverse… that’s more than a huge leap of imagination. It’s a huge leap straight out of reality!

I’ve been trying to train our dog, Phoebe, to fetch a ball through a wormhole. She seems eager but nervous.

What’s the problem?

Decades ago there was a famous comedian by the name of Henny Youngman. He told the following joke — which, being no comedian myself, I will paraphrase.

  • I know a guy who wanted to set a mousetrap but had no cheese in his fridge. So he cut a picture of a piece of cheese from a magazine, and used that instead. Just before bed, he heard the trap snap shut, so he went to look. In the trap was a picture of a mouse.

Well, with that in mind, consider this:

  • Imaginary cheese can’t catch a real mouse, and an imaginary wormhole can’t transport a real dog!
(more…)
Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 9, 2022

Read More

Mars Meets the Moon

A break from all these wormholes and strings; let’s take a moment to look at the sky. In the US, sadly, most of the country will be under cloud, but for those who aren’t, you have a spectacle tonight, at around 10-11pm Eastern Time in the US, roughly 5-6 am UT in Northern Europe.

It’s not terribly unusual for the Moon to pass in front of a planet and block it, from the point of view of some of us on Earth. This time it is Mars’ turn. You’ll be able to see the Moon eclipsing Mars (a “lunar occultation” of Mars), weather permitting, in the region shown below. This map is taken from in-the-sky.org, where you can enter your location and find out exactly when you’ll see Mars disappear behind the Moon and then reappear.

Visibility of tonight’s occultation of Mars by the Moon. See in-the-sky.org for more details.

This should be fun even with the naked eye — Mars won’t disappear in an instant but will do so gradually — but it will be better with binoculars, and great in a small telescope. It will give you a chance to see that yes, the Moon is in slow, steady motion in the sky relative to the planets, which (being further) seem to move more slowly. Lunar and solar eclipses provide a similar opportunity to observe this motion, but I think occultations provide the clearest sense of it.

The Full Moon can be seen from south to north across the Earth. Why isn’t the occultation visible everywhere? It is because the Moon is smaller than the Earth, as I explained here as part of my series on “Do It Yourself Astronomy”. In a sense, the light of Mars effectively (though not literally) casts the Moon’s shadow onto the Earth, and the shadow’s width — the width of the region over which the occultation is visible — would be the same as the diameter of the Moon, were the occultation visible close to the Earth’s equator. (As I pointed out, you can use this fact to measure the Moon’s size without ever leaving the Earth.) Because tonight’s occultation is visible closer to the poles, the region of visibility on the Earth’s surface is distorted by the Earth’s curvature, making it larger than the Moon by about 50% — about 3000 miles (5000 km) or so. (That’s yet more evidence that the Earth’s not flat, in case you needed some.)

Finally, there’s something quite remarkable about this occultation. It occurs close to two special moments:

  1. almost at full Moon (within a few hours);
  2. almost at “Mars opposition” (within a few hours) — when Mars is (nearly) closest, brightest and highest in the midnight sky, as brilliant as it gets over its cycle.

Since (1) happens once a month, and (2) happens once every two years, and occultations don’t occur all the time, this seems like quite a coincidence!

Only… it’s not as big a coincidence as it looks. A puzzler for you: why isn’t it a coincidence that (1) and (2) happen at the same time? That is, if there’s an lunar occultation of Mars at full Moon, why must Mars be nearly at opposition? [Hint: it’s just geometry.]

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 7, 2022

Read More

How Do You Make a Baby Cartoon Wormhole In a Lab?

This post is a continuation of the previous one, which you should read first…

Now, what exactly are these wormholes that certain physicists claim to be trying to make or, at least, simulate? In this post I’ll explain what the scientists did to bring the problem within reach of our still-crude quantum computers. [I am indebted to Juan Maldacena, Daniel Jafferis and Brian Swingle for conversations that improved my understanding.]

An important point from last post: a field theory with quarks and gluons, such as we find in the real world or such as we might find in all sorts of imaginary worlds, is related by the Maldacena conjecture to strings (including quantum gravity) moving around in more dimensions than the three we’re used to. One of these dimensions, the “radial dimension”, is particularly important. As in the previous post, it will play a central role here.

Einstein-Rosen Bridge (ER) vs. Einstein-Podolsky-Rosen Entanglement (EPR)

It’s too bad that Einstein didn’t live long enough to learn that two of his famous but apparently unrelated papers actually describe the same thing, at least in the context of Maldacena’s conjecture. As Maldacena and Lenny Susskind explored in this paper, the Maldacena conjecture suggests that ER is the same as EPR, at least in some situations.

We begin with two identical black holes in the context of a string theory on the same curved space that appears in the Maldacena conjecture. These two black holes can be joined at the hip — well, at the horizon, really — in such a way as to form a bridge. It is not really a bridge in spacetime in the way you might imagine a wormhole to be, in the sense that you can’t cross the bridge; even if you move at the speed of light, the bridge will collapse before you get to the other side. Such is the simplest Einstein-Rosen bridge — a non-traversable wormhole.

What, according to the Maldacena conjecture, is this bridge from the point of view of an equivalent field theory setting? The answer is almost fixed by the symmetries of the problem. Take two identical field theories that would each, separately, be identical to one of the two black holes in the corresponding string theory. These two theories do not affect each other in any way; their particles move around in separate universes, never interacting. Despite this, we can link them together, forming a metaphorical bridge, in the most quantum sense you can imagine — we entangle them as much as we can. What does this mean?

(more…)
Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 6, 2022

Read More

Physicists Discover String Theory and Extra Dimensions in a Laboratory!

With a headline like that, you probably think this is a parody. But in fact, I’m dead serious. Not only that, the discovery was made in the 1960s.  Due to an accident of history, the physicists involved just didn’t realize it back then.

That said, there are profound problems with this headline.  But the headlines we’ve seen this week, along the lines that “Physicists create a baby wormhole in the laboratory”, are actually WORSE than this one. 

It is more accurate to say that “string theory and extra dimensions were discovered experimentally in the 1960s” than to say that “a baby wormhole was created in a lab in the early 2020s.” 

And now I’m going to show you why. As you’ll see in this post and the next, the two claims are related.

(more…)
Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 5, 2022

Read More

[Not] A Wormhole in a Laboratory

Well, now…

  • Did physicists create a wormhole in a lab? No.
  • Did physicists create a baby wormhole in a lab? No.
  • Did physicists manage to study quantum gravity in a lab? No.
  • Did physicists simulate a wormhole in a lab? No.
  • Did physicists make a baby step toward simulating a wormhole in a lab? No.
  • Did physicists make a itty-bitty baby step toward simulating an analogue of a wormhole — a “toy model” of a wormhole — in a lab? Maybe.

Don’t get me wrong. What they did is pretty cool! I’d be pretty proud of it, too, had I been involved. Congratulations to the authors of this paper; the methods and the results are novel and thought-provoking.

But the hype in the press? Wildly, spectacularly overblown!

I’ll try, if I have time next week, to explain what they actually did; it’s really quite intricate and complicated to explain all the steps, so it may take a while. But at best, what they did is analogous to trying to learn about the origin of life through some nifty computer simulations of simple biochemistry, or to learning about the fundamental origin of consciousness by running a new type of neural network. It’s not the real thing; it’s not even close to the real thing; it’s barely even a simulation of something-not-close-to-the-real-thing.

(more…)
Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 1, 2022

Read More

In Brief: Unfortunate News from the Moon

Sadly, the LunaH-MAP mini-satellite (or “CubeSat”) that I wrote about a couple of days ago, describing how it would use particle physics to map out the water-ice in lunar soil, has had a serious setback and may not be able to carry out its mission. A stuck valve is the most likely reason that its thruster did not fire when instructed to do so, and so it has sailed past the Moon instead of going into the correct orbit. There’s still some hope that the situation can be salvaged, but it will take some luck. I feel badly for the scientists involved, who worked so hard and now face great disappointment.

In fact at least four and perhaps five of the ten CubeSats launched along with NASA’s Artemis mission have apparently failed in one way or another. This includes the Near-Earth Asteroid Scout and Team Miles, both of which were intended to test and use new technologies for space travel but with whom communication has not been established, and OMOTENASHI, which is intended to study the particle physics environment around the Moon and land a mini-craft on the surface, but which has had communication issues and will not be able to deploy its lander. It’s not clear what’s happening with Lunar-IR either.

One has to wonder whether this very high failure rate is due to the long delays suffered by the Artemis mission. The original launch date was at the end of August; batteries do degrade, and even satellites designed for the rigors of outer space can suffer in Florida’s heat and moisture.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON November 24, 2022

Read More
Search

Recent Posts

Buy The Book

Reading My Book?

Got a question? Ask it here.

Media Inquiries

For media inquiries, click here.

Order Waves In An Impossible Sea

Harvard Book Store
Amazon
Audiobook: Audible
Barnes & Noble
Powell's Books
Elliot Bay Book Company
Vroman's Bookstore