The Orion's Arm Universe Project Forums





Harold White's warp drive and OA
#11
Shocked 
A lot of GR phenomena such as wormholes and warp drives can actually be simulated in metamaterials:

How to Build a Warp Drive using Metamaterials

Not just Science Fiction: Electromagnetic Wormholes Possible, say Mathematicians

There have been any number of "No-Go" attempts on both for the past 25 years at least, and the fact that we haven't found any such theorems coupled with finding examples in fields such as material science actually makes me hopeful that someday our descendants may be able to construct them.

Physics is cool!
Reply
#12
The Pdf on the NASA site was taken down, but I still have his paper on my computer (it was freely accessible on the NASA site). This is the bit I found most interesting. His version acts as a FTL "booster" for a more conventional propulsion system. Basically, he seems to be saying that a fusion rocket that travels at *edit* .2c will be boosted up to 20c *edit*.



"The concept of operations as described by Alcubierre is that the spacecraft would depart the point of
origin (e.g. earth) using some conventional propulsion system and travel a distance d, then bring the
craft to a stop relative to the departure point. The field would be turned on and the craft would zip off
to its stellar destination, never locally breaking the speed of light, but covering the distance in an
arbitrarily short time period of time just the same. The field would be turned off a similar standoff
distance from the destination, and the craft would finish the journey conventionally. This approach
would allow a journey to say Alpha Centauri as measured by an earth bound observer (and spacecraft
clocks) measured in weeks or months, rather than decades or centuries.
A paradox identified in [6] is an issue that arises due to the symmetry of the energy density about the x
= xs surface. When the energy density is initiated, the choice in direction of the +x-axis is mathematically
arbitrary, so how does the spacecraft “know” which direction to go? Comparing Figure 1 to Figure 2
visually displays the asymmetry of the York Time and the symmetry of the energy density. Both sets of
three frames were purposely aligned to make direct comparison easier. This asymmetry/symmetry
paradox issue can be potentially resolved when considering the canonical form of the metric derived by
using a gauge transformation in [6] as shown in equation 4.

Using this new information, a modified concept of operations is proposed that may resolve the
asymmetry/symmetry paradox. In this modified concept of operations, the spacecraft departs earth and
establishes an initial sub-luminal velocity vi, then initiates the field. When active, the field’s boost acts on
the initial velocity as a scalar multiplier resulting in a much higher apparent speed, <veff>= γ vi as
measured by either an earth bound observer or an observer in the bubble. Within the shell thickness of
the warp bubble region, the spacecraft never locally breaks the speed of light and the net effect as seen
by earth/ship observers is analogous to watching a film in fast forward. Consider the following to help
illustrate the point – assume the spacecraft heads out towards Alpha Centauri and has a conventional
propulsion system capable of reaching 0.1c. The spacecraft initiates a boost field with a value of 100
which acts on the initial velocity resulting in an apparent speed of 10c. The spacecraft will make it to
Alpha Centauri in 0.43 years as measured by an earth observer and an observer in the flat space-time
volume encapsulated by the warp bubble. While this line of reason seems to resolve the paradox, it also
suggests that the York Time may not be the driving phenomenon, rather a secondary result. In this
physical explanation of the mathematics, the York Time might be thought of as perhaps a Doppler strain
on space as this spherical region is propelled through space. A pedestrian analog to use to help envision
this concept would be to consider the hydrodynamic pressure gradients that form around a spherical
body moving through a fluid – the front hemisphere has a high pressure region while the rear
hemisphere has a low pressure region. Analogously, the warp bubble travelling through space-time
causes space to pile up (contract) in front of the bubble, and stretch out (expand) behind the bubble.
Reply
#13
Actually, if I'm reading this right the ship would go from .2c to 20x c, not 200% (or 2x) c.

I have no idea if this is a reasonable idea or not. In OA, we presume that the archai are somehow able to influence the properties of a warp bubble using equipment inside it such that it 'warps' in whatever direction and at whatever (sub-c) velocity is desired.

What is described here seems less advanced than that, but we'll need Adam to weigh in on whether this particular warp drive seems workable in any fashion or not.

ToddSmile
Reply
#14
(05-10-2013, 11:31 AM)Drashner1 Wrote: Actually, if I'm reading this right the ship would go from .2c to 20x c, not 200% (or 2x) c.

I have no idea if this is a reasonable idea or not. In OA, we presume that the archai are somehow able to influence the properties of a warp bubble using equipment inside it such that it 'warps' in whatever direction and at whatever (sub-c) velocity is desired.

What is described here seems less advanced than that, but we'll need Adam to weigh in on whether this particular warp drive seems workable in any fashion or not.

ToddSmile

Not sure why I wrote 2 times the speed of light rather than 20...

As far as I can tell, this paper also makes no mention of the need for tachyonic matter, massive amounts of hawking radiation building up in the bubble etc.
Reply
#15
http://earthtech.org/publications/davis_...ence_2.pdf

Here is White's 2011 paper. Unfortunately, it's miles over my head.
Reply
#16
(05-28-2013, 10:40 AM)Sim Koning Wrote: http://earthtech.org/publications/davis_...ence_2.pdf

Here is White's 2011 paper. Unfortunately, it's miles over my head.

Wow! Me too... But thanks for the link all the same!
Reply
#17
(05-28-2013, 10:40 AM)Sim Koning Wrote: http://earthtech.org/publications/davis_...ence_2.pdf

Here is White's 2011 paper. Unfortunately, it's miles over my head.

A few notes:

1. This requires a very specific model of spacetime, the Chung-Freese metric
2. The article is cited only once in INSPIRE-HEP, by a publication from the same institute, indicating it's not well read/accepted
3. The experiment described in the paper should be fairly simple to do. There are no reports of the experiment being successfully replicated.

The paper describes a way to get negative energy density from positive energy. However, none of the other bad effects (e.g. causality violation, non-unitarity) have been resolved.

None of these items completely rules out this model, but Alcubierre's original paper, by contrast, was cited 136 times and there have been numerous follow-on papers. This implies that most people in the field don't take White's idea seriously. And of course, if we live in something other than the Chung-Freese spacetime, all bets are off.

BTW, the Van Den Broeck paper/metric on which OAUP's current warp drives are based have been cited 32 times.

http://inspirehep.net/search?ln=en&ln=en...rg=25&sc=0
Reply
#18
http://archive.thespaceshow.com/shows/19...-01-04.mp3

Here is an interview with Harold White and Eric Davis regarding the paper and the experiments.

It looks like his more recent paper (the one that was all over the news) is back up on the NASA site: http://ntrs.nasa.gov/archive/nasa/casi.n...016932.pdf
Reply
#19
I'd like to have someone with better physics knowledge than me (which isn't difficult; my qualifications have thirty years of rust on them and were in biochemistry in the first place) to clear something up. It's not really relevant to OA, because it is to do with superluminal (Alcubierre and now White) warp drives. Apologies for that.

From what I've read, the drive needs to build up really large amounts (Jupiter mass or thereabouts) of positive energy at the sides of the bubble, with a roughly equal amount of negative energy at the front and back. If that's the case, is there really a problem? Sure, handling extremely large amounts of energy is going to be necessary - but generating large amounts is not.
Reply
#20
http://www.nytimes.com/2013/07/23/scienc...l?_r=1&amp;

New interview.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)