Alcubierre Drive vs the Hubble Constant

[dan_r]

Dear all, I was reading about the Alcubierre drive, and although there's the more recent issue with Hawking radiation potentially frying everything within the warp field that's generated, I was wondering whether there had been any thought given to the possibility of the drive being flung parsecs in the wrong direction upon activation if the two warp fields aren't adjusted in such a way to take the Hubble constant into account?

As I understand it, there's the 'relatively' constant speed of universal expansion being (from the WMAP site) 70.8 ± 1.6 (km/s)/Mpc in flat space or 70.8 ± 4.0 (km/s)/Mpc otherwise.

Could the creation of a space-time warp according Alcubierre's hyopthesis cause the drive to be completely removed from the local space-time frame of reference and be flung into history as opposed to propelling it to worlds unknown? Would it actually be possible to operate such a drive accurately until we can calculate the absolute directions and angles in which the Universe is expanding and compensate the strength of the fields to take that into account?

 

[bcrowell]

As I understand it, there's the 'relatively' constant speed of universal expansion being (from the WMAP site) 70.8 ± 1.6 (km/s)/Mpc in flat space or 70.8 ± 4.0 (km/s)/Mpc otherwise.

The figure you're quoting isn't a velocity -- note its units. We have a FAQ entry that may be relevant: https://www.physicsforums.com/showthread.php?t=508610

It will probably be easier to have a discussion that will be helpful to you if you tell us something about your background in math and physics.

[...]I was wondering whether there had been any thought given to the possibility of the drive being flung parsecs in the wrong direction upon activation if the two warp fields aren't adjusted in such a way to take the Hubble constant into account?

From what I understand about the Alcubierre spacetime, there is no "activation." WP says, "[...]there are no known methods to create such a warp bubble in a region that does not already contain one, or to leave the bubble once inside it,[...]"

 

[dan_r]

The figure you're quoting isn't a velocity -- note its units. We have a FAQ entry that may be relevant: https://www.physicsforums.com/showthread.php?t=508610

It will probably be easier to have a discussion that will be helpful to you if you tell us something about your background in math and physics.


From what I understand about the Alcubierre spacetime, there is no "activation." WP says, "[...]there are no known methods to create such a warp bubble in a region that does not already contain one, or to leave the bubble once inside it,[...]"

I'm a complete beginner! I'm starting my studies in September after a career in law and politics, so it's totally new to me. I keep coming across all these interesting things though, and I'm trying to get an idea in my head how things gel together.

I assumed that if, in a hypothetical situation, one had access to a functioning Alcubierre drive then once the two warp fields were activated the drive itself enters the Alcubierre spacetime, hence the 'activation'. And as I stated above, in this hypothetical situation, it may well be the case that the bubble would remain static while the Universe continued to expand ahead of it.

Like your quote says though, there are no known methods of causing this to happen so I guess it's a pointless question.

 

[bcrowell]

I'm a complete beginner! I'm starting my studies in September after a career in law and politics, so it's totally new to me.

Cool! So you're starting an undergrad degree in physics...?

 

[dan_r]

Cool! So you're starting an undergrad degree in physics...?

At the grand old age of 35 indeed I am! I'm doing two year's distance learning to get myself refreshed - my original background was in Biology, but I ended up working in law and politics strangely.

On completion of that you go to university proper, but skip ahead to the second year. There's the option of doing an 'undergraduate masters' if you do well in the second year.. not completely sure about that, but it would appear that you can go straight on to doing your PhD instead of completing a standalone post-grad masters.

But yes, I am very rusty with some of the fundamentals.. I was last at uni in 1996 ;)