Scientists Announce a Physical Warp Drive Is Now Possible. Seriously.

[arthwollipot]

Scientists Announce a Physical Warp Drive Is Now Possible. Seriously.

Humans are one step closer to traveling at faster-than-light speeds.

www.popularmechanics.com

...This brings us to the new study, which scientists in the Advanced Propulsion Laboratory (APL) at Applied Physics just published in the peer-reviewed journal Classical and Quantum Gravity. In the report, the APL team unveils the world's first model for a physical warp drive—one that doesn't require negative energy.

The study is understandably pretty thick (read the whole thing here), but here's the gist of the model: Where the existing paradigm uses negative energy—exotic matter that doesn't exist and can't be generated within our current understanding of the universe—this new concept uses floating bubbles of spacetime rather than floating ships in spacetime.

The physical model uses almost none of the negative energy and capitalizes on the idea that spacetime bubbles can behave almost however they like. And, the APL scientists say, this isn't even the only other way warp speed could work. Making a model that's at least physically comprehensible is a big step.

Plus, Alcubierre himself has endorsed the new model, which is like having Albert Einstein show up to your introductory physics class.

The word "almost" is doing an awful lot of heavy lifting in that third paragraph. The abstract (most of the paper is way above my education level) says that they have decreased the negative energy requirement by two orders of magnitude. That's not zero. There's also this, from the Discussion section:

At last in the subluminal case, warp drive spacetimes may be constructed by using purely positive energy density, as presented in Section 3 for the spherically symmetric case. They can likewise be constructed using purely negative energy density, as is the case for the Alcubierre solution, or constructed using both positive and negative energy density. In Section 3 we showed, for the first time, that the only type of modification to the internal spacetime that is achievable with purely positive energy for spherically symmetric warp drives is slowing down the rate of time inside the craft.

I have no idea what this means.

I also wish they'd got someone other than Sabine Hossenfelder to do a video about it.

 

[bigred]

Not sure how this is news? Theoretically, warp drive has always been possible.

 

[arthwollipot]

Not sure how this is news? Theoretically, warp drive has always been possible.

The original Alcubierre drive required negative energy density in order to be applicable. Since as far as we know there is no kind of matter that has a negative energy density, and we're not even sure what that would look like, the Alcubierre drive has always been a curiosity on the fringes of relativity.

The new proposal either doesn't require a negative energy density, or the negative energy density requirement is much, much lower (I can't tell which), it is far more feasible.

 

[Darat]

I think (and that "think" is doing a lot lifting!) in the purely positive energy version the spacecraft wouldn't exceed the speed of light in our reference frame so as far as we are concerned it will still take the spaceship a hundred years to get to Delta Draconis but for the crew it would be much less time, so it may be for the crew they can "engage" the warp drive and arrive pretty much instantaneously - to them - at Delta Draconis. It's an extreme version of "time dilation".

 

[shemp]

Popular Mechanics was once a respected publication. It is now the Daily Mail of science.

 

[3point14]

So this method requires slightly fewer impossible materials than the last one..?

 

[theprestige]

So this method requires slightly fewer impossible materials than the last one..?

No. This method requires no impossible materials, but only for sub light speeds, and only provides time dilation for the ship in transit.

The same analysis also says that the super light speed method requires less impossible material than previously theorized.

I bet even the possible method still requires far more mass-energy than we have acces to, or any hope of controlling.

That's the bit that never seems to come up in these articles. Warping spacetime in any practically significant way requires a lot of mass-energy. Look at how much mass it takes to appreciably precess the perihelion of Mercury's orbit. And those are rookie numbers, gonna have to pump those numbers way up, if you want interstellar voyages of any appreciable payload.

So yeah, I imagine this paper says it's "possible" for a warp drive colony ship to Alpha Centauri in a single life time. Of its passengers, not the generations of observers on Earth. As long as you have several (hundred? thousand?) solar masses (or equivalent energy) to work with.

Which brings up another point. Testing a warp drive at any appreciable scale will probably have to be done in deep space - Kuiper distances, at least - to avoid the risk of knocking half the solar system out of orbit when you start flaring gravity waves willy-nilly.

 

[The Atheist]

So this method requires slightly fewer impossible materials than the last one..?

They're looking the wrong way..

Clearly, the infinite improbability drive is equally possible.

And a lot more fun.

 

[arthwollipot]

No. This method requires no impossible materials, but only for sub light speeds, and only provides time dilation for the ship in transit.

The same analysis also says that the super light speed method requires less impossible material than previously theorized.

That's a good explanation - thanks.

I bet even the possible method still requires far more mass-energy than we have acces to, or any hope of controlling.

That's the bit that never seems to come up in these articles. Warping spacetime in any practically significant way requires a lot of mass-energy. Look at how much mass it takes to appreciably precess the perihelion of Mercury's orbit. And those are rookie numbers, gonna have to pump those numbers way up, if you want interstellar voyages of any appreciable payload.

So yeah, I imagine this paper says it's "possible" for a warp drive colony ship to Alpha Centauri in a single life time. Of its passengers, not the generations of observers on Earth. As long as you have several (hundred? thousand?) solar masses (or equivalent energy) to work with.

Which brings up another point. Testing a warp drive at any appreciable scale will probably have to be done in deep space - Kuiper distances, at least - to avoid the risk of knocking half the solar system out of orbit when you start flaring gravity waves willy-nilly.

Indeed, this would be a technology for a K2 civilisation at lowest, methinks.

 

[theprestige]

If we're looking for alien civilizations of any import, we should be looking for early galaxies or quasars winking out of existence, as the civilizations with access to those mass-energy concentrations harness them to generate causality-violating spacetime warps. We should also be looking for antecedents and procedents of such spacetime warping. And if we're really ambitious, setting up some sort of spacetime beacon to attract those distant but also too-near civilizations to our infinitesimal scrap of the spacetime continuum.