computing precise insights modeling precise understanding modeling calibrated estimations delivering precise wisdom composing critical estimations mapping the future mapping accurate understanding computing definitive insights mapping critical futures assembling contingent predictions calculating predictive understanding forecasting probable estimations computing intelligent understanding assembling probable forecasts

Question

Metaculus Help: Spread the word

If you like Metaculus, tell your friends! Share this question via Facebook, Twitter, or Reddit.

Will a sample of negative energy be produced by 2100?

Warp drives. Wormholes. Time machines. These exotic structures are the stuff of science fiction, but also have valid mathematical structures behind them in the form of spacetime "metrics" one can write down with the requisite properties.

There is one major physical issue standing in the way actually making them, however: all these possibilities require negative energy.

More specifically, relativists have devised a number of mathematical conditions that may be assumed regarding matter and energy, known as "energy conditions." Wormhole, warp-drive, and time-machine solutions to Einstein's equations essentially always require some substance that violates the "weak energy condition" (WEC), and generally others. Most simply, the WEC states that in the restframe of a material, its energy density is non-negative. (Technically the substance's pressure also must be sufficiently non-negative; see e.g. here for a brief description, and a good relativity text like this one for more gory detail, and here for a recent, interesting review.)

These energy conditions are generically violated at the quantum level, because quantum mechanics entails uncertainty in the energy of a system over a very short time period, so must allow very brief negative-energy fluctuations. But macroscopic amounts of negative energy do not appear possible with any particles or fields we know to exist.

On the other hand, it is somewhat unclear what fundamentally forbids negative energy. Negative energy particles would be bad news, as they would likely render low-energy particles unstable to decay into positive and negative energy ones – such a universe would not last long. But could we devise some strange substance that has the property, using something like the Casimir effect, that takes empty space and removes some energy from it? It sees plausible that negative energy is closely related to violations of the second law of thermodynamics, which would mean that it is very, very hard to violate. But maybe not impossible. "Violations" of the second law (downward movements in entropy) can happen if you wait long enough, or if you set up very, very careful initial conditions (see, e.g. here) So it does not seem impossible that with a high level of tuning a sample of negative energy could be made, though the author is not at all clear how...

So instead we ask:

Will a sample of negative energy material be created by the year 2100?

To be specific, we'll ask whether > 10 proton masses worth of negative energy will be created and confined to a volume of less than 1 cubic centimeter for longer than 1 microsecond, in such a way that during that microsecond there exists a volume of space that could be considered to have a mass of less than -10 proton masses. (As of 2017, the record for antimatter, an altogether easier substance to make, was about 300 proton masses.)

{{qctrl.predictionString()}}

Metaculus help: Predicting

Predictions are the heart of Metaculus. Predicting is how you contribute to the wisdom of the crowd, and how you earn points and build up your personal Metaculus track record.

The basics of predicting are very simple: move the slider to best match the likelihood of the outcome, and click predict. You can predict as often as you want, and you're encouraged to change your mind when new information becomes available. With tachyons you'll even be able to go back in time and backdate your prediction to maximize your points.

The displayed score is split into current points and total points. Current points show how much your prediction is worth now, whereas total points show the combined worth of all of your predictions over the lifetime of the question. The scoring details are available on the FAQ.

Note: this question resolved before its original close time. All of your predictions came after the resolution, so you did not gain (or lose) any points for it.

Note: this question resolved before its original close time. You earned points up until the question resolution, but not afterwards.

This question is not yet open for predictions.

Thanks for predicting!

Your prediction has been recorded anonymously.

Want to track your predictions, earn points, and hone your forecasting skills? Create an account today!

Track your predictions
Continue exploring the site

Community Stats

Metaculus help: Community Stats

Use the community stats to get a better sense of the community consensus (or lack thereof) for this question. Sometimes people have wildly different ideas about the likely outcomes, and sometimes people are in close agreement. There are even times when the community seems very certain of uncertainty, like when everyone agrees that event is only 50% likely to happen.

When you make a prediction, check the community stats to see where you land. If your prediction is an outlier, might there be something you're overlooking that others have seen? Or do you have special insight that others are lacking? Either way, it might be a good idea to join the discussion in the comments.