No, we can’t make wormholes no matter how weird they are
I have been debating what to do about this news story that came out yesterday. I have been fuming about it. I was going to put it away and…
An article in Popular Mechanics about wormholes came out recently that suggested that wormholes might “work” if they are weirdly shaped. The article takes its cues from another article on space.com which takes its info from a pre-print on the arXiv.com preprint server. This game of science telephone seems to have distorted the original message of the paper, which was hardly about how to build wormholes.
If Wormholes Are Actually Going to Work, They'll Need to Look Weird
KTSDESIGN/SCIENCE PHOTO LIBRARY In a new, unreviewed paper, researchers suggest the conditions that could have created…www.popularmechanics.com
The headlines aren’t exactly false if you interpret “work” as “maybe physically possible if you make a lot of assumptions about how the physics of gravity works very, very, very, very close to the Big Bang at scales so tiny we have no idea what happens”. And, in fairness, that fact is buried in the articles, just not up front.
The article that I assume it is based on is more explanatory, which is good, but I feel may miss the point as well. This is not a step towards traveling faster than light. It is something else entirely. It is a potential window into understand how our universe came to be.
Weirdly-shaped wormholes might work better than spherical ones
Wormholes, or tunnels in the fabric of space-time, are ferociously unstable. As soon as even a single photon slips down…www.space.com
The articles quote some things from the paper (which has not been peer reviewed) without explaining them like “improved running coupling” and “antiscreening”, which I took to mean that perhaps the article writers thought maybe people would appreciate the jargon. (Otherwise, why mention them at all?)
All that told, I liked the paper itself, written by some Iranian researchers. Although I didn’t slog through checking their math, I did appreciate what they were trying to do. I’m afraid that if they had known the news media would pick it up, they might have tried harder to explain why their work is interesting in lay terms.
In reality, what they wanted to show was that at extremely high energies and small scales, quantum gravity might allow wormholes without needing “exotic matter”. I wrote an article recently about this and why the need for exotic matter made all FTL travel impossible.
They showed that if you assume asymptotic safety, the idea that quantum gravity becomes nicely behaved at extremely high energy and small scales, and that the universal gravitational constant runs towards something nice, then you can show that at Grand Unification Theory (GUT) energies wormholes are possible without exotic or negative matter.
The caveats are that GUT energies are around the Planck time, 0.0…01 (there are 42 zeros after the dot) seconds after the Big Bang. Also, they showed that their wormholes were only 14 Planck lengths wide, so even an electron couldn’t fit through. (The Planck length is the theoretical smallest measurable length.) It would be wide enough to accommodate Planck size black holes however.
Their theory is based on the idea that universal physical constants change at higher and higher energies. Part of this happens because of “screening”. In quantum physics, there are many, many interactions all the time. When we make a quantum measurement of a coupling constant like the fine structure constant or the universal gravitational constant, we are actually measuring interactions at one energy scale combined with interactions at higher ones that we can’t see. That means that high energy interactions of particles can “screen out” the effects of the interactions at the energy scales we are measuring at. The higher energy you measure at the less screening there is. You can also get the opposite where these interactions augment the coupling constant. That is called “antiscreening”. The authors are arguing that gravitational interactions are weaker at higher energies because of antiscreening, which to me is a reasonable assumption. That is critical for asymptotic safety arguments.
The academic writers make no mention of FTL travel and for the life of me I couldn’t figure out if the region of validity for their wormholes was FTL or not. An FTL wormhole is one that lets you travel between two points faster than the speed of light and has major implications on causality. A non-FTL wormhole is, on the other hand, entirely plausible within known physics since there are no causal violations. Since their wormholes were “quantum” in scale and energy, it probably doesn’t matter since quantum phenomena violate the speed of light and causality all the time.
The paper is interesting to me because it suggests that these wormholes might have played a role in the early formation of the universe, which has implications on issues like inflationary theory and what we see in the Cosmic Microwave Background. We certainly have a lot of questions about that time and how what happened when the universe began might have impacted the way it looks now.