# Stardrive technology? **URL:** \ **Category:** Factual Questions\ **Created:** [November 8, 2010, 9:11pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959 "2010-11-08T21:11:52Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [November 9, 2010, 12:13pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/21 "2010-11-09T12:13:15Z")
> [@Frylock](#): > > With God, everything is possible. Why does God need a wormhole? ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 9, 2010, 1:59pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/22 "2010-11-09T13:59:08Z")
What would the gravity difference do? It would seem like the contents of the sun would just spill out the wormhole like a hole in a high pressure tank. Would gravity travel through the wormhole also? > [@runner pat](#): > > Why does God need a wormhole? For His children to play, but then a aspect that I didn’t consider: > [@](#): > > One book I read (many years ago, no idea of the title but the series used classic movie plots) used the wormhole to the centre of the sun as a nifty weapon. Always seems like someone trying to turn a great gift into a weapon. ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [November 9, 2010, 3:20pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/23 "2010-11-09T15:20:32Z")
> [@Der\_Trihs](#): > > But will he cooperate when you try to lock him in the engine compartment? He will if he wants to be fed. “No loaves and fishes for you 'til we get to Alpha Centauri!” But seriously. Would the pressure in the solar core be able to overcome the gravity, and “squirt” the core plasma out the wormhole? The physics of that are beyond me. Anyone else want to try? ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [November 9, 2010, 3:37pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/24 "2010-11-09T15:37:05Z")
> [@Cheshire\_Human](#): > > But seriously. Would the pressure in the solar core be able to overcome the gravity, and “squirt” the core plasma out the wormhole? The physics of that are beyond me. Anyone else want to try? If you open the wormhole at the center of the star, there is no gravity (all the mass of the star is pulling away from the center with a net zero force). So compression pressure will force solar core material out the wormhole without any problem. Si ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 9, 2010, 6:11pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/25 "2010-11-09T18:11:55Z")
Quoth **Der Trihs** : > [@](#): > > I’d think then that electromagnetic radiation from the interior of the star would make the trip just fine. That’s a rather good power source right there. It wouldn’t be all that much better than what you can get from solar panels (which do, after all, work based on electromagnetic radiation from a star making the trip to your spaceship). As for the gravity gradient, think of it this way: If the star material _did_ just squirt out the end of the wormhole, you could then drop it back down to the star through normal space, and make an Escherian water-wheel (a perpetual-motion machine). Even wormholes must obey the law of conservation of energy, so that’s not going to happen. Quoth **brossa** : > [@](#): > > Is it easier to push something through the wormhole if the other end is on Ceti Alpha V (local gravity 1G) than if it is in Earth orbit? That might work (though depending on how wormholes work, you might need some sort of siphon effect), but the local gravitational field isn’t relevant, it’s the local gravitational _potential_. Think of a hilly landscape, and trying to get water from one point on the landscape to another. The gravitational potential is analogous to the height: You can easily get water from one point to another point with the same or lower elevation. The gravitational field, though, is analogous to the steepness of the slope, and that’s irrelevant to whether you can get water somewhere. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 9, 2010, 6:29pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/26 "2010-11-09T18:29:35Z")
> [@Whack-a-Mole](#): > > Doesn’t Hawking Radiation involve negative energy? When a virtual particle is created and one part of that falls into a black hole doesn’t that part become negative energy while the escaped half becomes positive energy? > > Obviously we can’t get our hands on the stuff in the BH but if Hawking radiation is real then the stuff does exist. The particle itself has a positive energy density (positive mass) it only has negative energy with respect to its position in the holes gravitational field (in other words its potential energy is negative). ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 9, 2010, 6:41pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/27 "2010-11-09T18:41:08Z")
> [@Ring](#): > > The particle itself has a positive energy density (positive mass) it only has negative energy with respect to its position in the holes gravitational field (in other words its potential energy is negative). Also, in case you’re wondering, the hole still loses mass/energy because it expended enough energy to create two real particles, but only got the energy of one particle back. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 9, 2010, 11:38pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/28 "2010-11-09T23:38:59Z")
> [@Chronos](#): > > As for the gravity gradient, think of it this way: If the star material _did_ just squirt out the end of the wormhole, you could then drop it back down to the star through normal space, and make an Escherian water-wheel (a perpetual-motion machine). Even wormholes must obey the law of conservation of energy, so that’s not going to happen. I think you may not be thinking of the overall picture. Wormholes can be thought of as sort of subspace tunnels, and outside the laws that govern 3d space, but can also obey the law of conservation of energy. There is no reason to assume that the law of conservation of energy would be violated, just that the resulting energy in the star may be reduced somehow. A star has energy that can be tapped into to and doing so does not violate the LoCoE, just like a coal fired power plant or the space shuttle doesn’t violate it, the question is where this ‘law’ will come into play. This seems no more a problem then the amount Jupiter had to slow down for the Voyager space probe to sling shot to Saturn. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 9, 2010, 11:50pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/29 "2010-11-09T23:50:51Z")
> [@Chronos](#): > > Quoth **Der Trihs** :It wouldn’t be all that much better than what you can get from solar panels (which do, after all, work based on electromagnetic radiation from a star making the trip to your spaceship). I don’t think so; the sunlight that reaches me on Earth is attenuated according to the inverse square law because it is spreading into open space. A wormhole would be more like a tunnel, with no place for the radiation to spread and with nothing to absorb it. I’d expect it to arrive with nearly the full force it had at its origin. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 10, 2010, 4:51am UTC](https://boards.straightdope.com/t/stardrive-technology/559959/30 "2010-11-10T04:51:22Z")
At best, what you’d get is a ball of something the size of the mouth of your wormhole, with an effective temperature the same as that of the star. Which isn’t really all that hot, compared to what we can produce artificially. Although, come to think of it, there’s nothing that says that the star end of the wormhole has to be near the surface. You could do significantly better by dipping your drinking straw down into the core. ---
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [November 10, 2010, 5:22am UTC](https://boards.straightdope.com/t/stardrive-technology/559959/31 "2010-11-10T05:22:25Z")
> [@Chronos](#): > > At best, what you’d get is a ball of something the size of the mouth of your wormhole, with an effective temperature the same as that of the star. Which isn’t really all that hot, compared to what we can produce artificially. > > Although, come to think of it, there’s nothing that says that the star end of the wormhole has to be near the surface. You could do significantly better by dipping your drinking straw down into the core. Why aren’t you making the input end of the wormhole larger than the output end? Capture all the photons leaving one hemisphere (well, some large fraction anyway) of the star and push them through a hole 1 meter across? ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [November 10, 2010, 5:01pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/32 "2010-11-10T17:01:42Z")
> [@Ring](#): > > the area between Casimir plates has a negative energy density, and I believe this is the type of exotic matter necessary to keep a wormhole open, but I’m not sure about that. If I remember correctly even **Chronos** didn’t know which specific flavor of exotic matter was necessary. One theoretical model for a warp drive system is to surround the spaceship with shells of Casimir plates, essentially enclosing the ship in a bubble of negative energy and allowing faster than light travel. The amount of energy within a set of Casimir plates is so tiny though, that to propel a decent sized spaceship at a decent speed would require a shell several light years thick. Not very practical. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [November 10, 2010, 6:14pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/33 "2010-11-10T18:14:10Z")
> [@Ring](#): > > Also, in case you’re wondering, the hole still loses mass/energy because it expended enough energy to create two real particles, but only got the energy of one particle back. This doesn’t make sense to me. I thought virtual particles are created everywhere all the time and do not need a black hole to borrow energy from. Further, if the particles borrowed energy from the BH then aren’t you saying energy escaped the BH? Isn’t that impossible? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 10, 2010, 9:40pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/34 "2010-11-10T21:40:06Z")
> [@](#): > > Why aren’t you making the input end of the wormhole larger than the output end? Capture all the photons leaving one hemisphere (well, some large fraction anyway) of the star and push them through a hole 1 meter across? Most of the photons would end up getting reflected back out of the hole, and you’d end up with an output no different than if you had just made the star end the same size as the ship end. Oh, and > [@](#): > > I think you may not be thinking of the overall picture. Wormholes can be thought of as sort of subspace tunnels, and outside the laws that govern 3d space, They’re not outside the laws that govern 3d space. There’s no physical boundary between “inside the tunnel” and “normal space”. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [November 10, 2010, 11:10pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/35 "2010-11-10T23:10:09Z")
> [@Chronos](#): > > At best, what you’d get is a ball of something the size of the mouth of your wormhole, with an effective temperature the same as that of the star. Which isn’t really all that hot, compared to what we can produce artificially. > > Although, come to think of it, there’s nothing that says that the star end of the wormhole has to be near the surface. You could do significantly better by dipping your drinking straw down into the core. That’s what I was thinking of actually. Besides, I wasn’t thinking so much of getting huge amounts of energy from it as the fact that it lets you feed energy to the ship at any distance. And a little mass too if particles are making the trip too, I’d think some would. That means you’ve potentially got yourself a drive that won’t run out of fuel for as long as the star is still active. Perhaps not a high acceleration one - but you can achieve relativistic velocities with a low acceleration drive if you can run it long enough. > [@Chronos](#): > > Most of the photons would end up getting reflected back out of the hole, and you’d end up with an output no different than if you had just made the star end the same size as the ship end. What would do the reflecting? I wouldn’t expect a real wormhole to have interior walls like you see on sci-fi shows; since it is a spacial distortion I’d expect moving side to side within the wormhole to bring you back where you started in a loop. Like circumnavigating the globe, or a closed universe. ---
**Author:** ![sleestak](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sleestak](https://boards.straightdope.com/u/sleestak)\ **Post date:** [November 11, 2010, 12:48am UTC](https://boards.straightdope.com/t/stardrive-technology/559959/36 "2010-11-11T00:48:14Z")
> [@Frylock](#): > > With God, everything is possible. Oh yeah? Could god microwave a burrito so hot that even he couldn’t eat it?\* Slee \*Simpsons reference ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 11, 2010, 3:15am UTC](https://boards.straightdope.com/t/stardrive-technology/559959/37 "2010-11-11T03:15:26Z")
> [@Whack-a-Mole](#): > > This doesn’t make sense to me. > > I thought virtual particles are created everywhere all the time and do not need a black hole to borrow energy from. Correct. _Virtual_ particles not _real_ particles. It takes energy to convert virtual to real. > [@](#): > > Further, if the particles borrowed energy from the BH then aren’t you saying energy escaped the BH? Isn’t that impossible? The hole has a gravitational field outside the horizon? And its immense tidal gravity creates the real particles. Virtual gravitons are not constrained by the speed of light. But exactly how this works is going to require **Chronon** to explain it. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 11, 2010, 5:23am UTC](https://boards.straightdope.com/t/stardrive-technology/559959/38 "2010-11-11T05:23:58Z")
Crap, I really y screwed that post up. Why is there a question mark, and who the hell is Chronon? I’ve read in sci.physics that Hawking Radiation is extremely complicated and almost impossible to explain to a non-physicist. I remember one fairly reputable scientist explain that the hole only acts as an enabler, similar to a photon of 1.02 MeV requiring a momentum absorber for electron anti electron pair production. Again, maybe **Chronos** could take a stab at explaining it, but I’m at my limit. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 11, 2010, 7:14pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/39 "2010-11-11T19:14:53Z")
First of all, here’s who John Baez is. > [@](#): > > John Carlos Baez (born June 12, 1961) is an American mathematical physicist and a professor of mathematics at the University of California, Riverside (UCR) in Riverside, California. He is known for his work on spin foams in loop quantum gravity. > > Snip > > Baez is also known to science fans as the author of This Week’s Finds in Mathematical Physics, an irregular column on the internet featuring mathematical exposition and criticism. He started This Week’s Finds in 1993 for the Usenet community, and it now has a worldwide following in its new form, the blog “Azimuth”. > **[John C. Baez](https://en.wikipedia.org/wiki/John_C._Baez)** > > John Carlos Baez (/ˈbaɪ.ɛz/ BY-ez; born June 12, 1961) is an American mathematical physicist and a professor of mathematics at the University of California, Riverside (UCR) in Riverside, California. He has worked on spin foams in loop quantum gravity, applications of higher categories to physics, and applied category theory. Additionally, Baez is known on the World Wide Web as the author of the crackpot index. > John C. Baez attended Princeton University where he graduated with an A.B. in mathem... And second here’s his take on Hawking Radiation, and its usual pop science explanation. > **[Hawking Radiation](https://www.desy.de/user/projects/Physics/Relativity/BlackHoles/hawking.html)** ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [November 11, 2010, 7:26pm UTC](https://boards.straightdope.com/t/stardrive-technology/559959/40 "2010-11-11T19:26:52Z")
> [@kanicbird](#): > > Always seems like someone trying to turn a great gift into a weapon. Like when my parents gave me that Transformer when I was a kid, and I threw it at my brother. Really makes you think, man. [Previous page](https://boards.straightdope.com/t/stardrive-technology/559959.md?page=1) [Next page](https://boards.straightdope.com/t/stardrive-technology/559959.md?page=3)