Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes

296 Pages·2013·8.48 MB·English

by  James F. Woodward (auth.)

Making Starships and Stargates
The Science of Interstellar Transport and Absurdly Benign Wormholes

James F. Woodward
Making Starships
and Stargates
The Science of Interstellar Transport and Absurdly Benign Wormholes
With illustrations by Nembo Buldrini
and
Foreword by John G. Cramer
JamesF.Woodward
Anaheim,California
USA
SPRINGER-PRAXISBOOKSINSPACEEXPLORATION
ISBN978-1-4614-5622-3 ISBN978-1-4614-5623-0(eBook)
DOI10.1007/978-1-4614-5623-0
SpringerNewYorkHeidelbergDordrechtLondon
LibraryofCongressControlNumber:2012948981
#JamesF.Woodward2013
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This book is dedicated to all those whose
lives have been affected by my seemingly
quixotic quest to find a way around spacetime
quickly, especially Carole and the cats.

Foreword
When I arrived in Seattle in the mid-1960s to assume my new faculty position at the
University of Washington, I remarked toone of mynew Physics Department colleagues
that the magnificent views of Mt. Rainier, available from many parts of the city, gave
Seattleaspecialanduniqueflavorandambiance.
“Youknow,”hesaid,“Rainierisdormantatthemoment,butit’sstillanactivevolcano.
It erupts every 5,000 years. The geological record shows regular thick ash falls from
Rainierandgiantmudflowsdowntheglacier-fedrivervalleys,wherealotofpeoplelive
now.”
“Really,”Isaid.“Whenwasthelasteruption?”
“Fivethousandyearsago,”hesaidwithaquirkysmile.
That anecdote provides a good analogy to our present situation, as residents of this
planet. All of our “eggs,” our cities, our people, our art and culture, our accumulated
knowledgeandunderstanding,arepresentlycontainedinoneprettyblue“basket”called
PlanetEarth,whichorbitsinaSolarSystemthatisconfiguredtohurlverylargerocksin
ourdirectionatrandomintervals.
BetweentheorbitsofMarsandJupiterliestheAsteroidBelt,acollectionoflargerocky
leftoversfromtheformationoftheSolarSystem.WithintheAsteroidBeltthereareempty
bandsknownastheKirkwoodZones,broadregionsinwhichnoasteroidsareobservedto
orbit. The Kirkwood Zones are empty because when any asteroid is accidentally kicked
intooneofthem,orbitalresonanceswithJupiterwillpropelitchaoticallyintoaneworbit,
sometimes one that dives into the inner Solar System and has the potential of impacting
Planet Earth. Thus, our planetary system has a built-in shotgun that, on occasion, sends
largerocksinourdirection.
Meteors come in all sizes, and it is estimated that a total of about 14 million tons of
meteoritic material falls upon Planet Earth each year, much of it from the debris of
asteroids and comets. About 65 million years ago a large rock, probably an asteroid,
impacted Earth in the vicinity of the Yucatan Peninsula, creating the Chicxulub crater,
180 km wide and 900 m deep. Some three quarters of Earth’s species became extinct
duringtheaftermathoftheChicxulubimpact,includingthedinosaurs.Thisisoneofthe
more recent examples of the approximately 60 giant meteorites 5 or more kilometers in
vii
viii Foreword
diameterthathaveimpactedEarthinthepast600millionyears.Eventhesmallestofthese
wouldhavecarvedacratersome95kmacrossandproducedanextinctionevent.
The geological fossil records show evidence of “punctuated equilibrium,” periods in
which life-forms expand and fit themselves into all the available ecological niches,
punctuated by extinction events in which many species disappear and the survivors
scrambletoadapttothenewconditions.
Life on Planet Earth may have been “pumped” to its present state by this cycle of
extinction and regeneration, but we do not want to get caught in the next cycle of the
pump.We,asaspecies,needtodiversify,toplaceoureggsinmanybasketsinsteadofjust
one,beforetheforcesofnatureproduceanotherextinctionevent.
Thebasicproblemwithsuch“basketdiversification”isthatweresideatthebottomofa
deepgravitywell,fromwhichthelawsofphysicsmakeitverydifficultforustoescape.
The only escape method presently in use involves giant chemical rockets that burn and
eject vast volumes of expensive and toxic fuel in order to lift tiny payloads out of the
gravitywellofEarth.
AndevenifwecanescapemostofEarth’sgravitywell,thingsarenotmuchbetterin
near-Earth orbit. The Solar System, outside Earth’s protective atmosphere and shielding
magneticfield,isafairlyhostileplace,withhardvacuumandtheSun’sflaresandstorms
sendingoutwavesofsterilizingradiation.Andhumanbiologyseemstorequirethepullof
gravityforahealthyexistence.Amicro-geespacestationisanunhealthyplaceforlong-
termhabitation,andastronautsreturnfromextendedstaysthereasnear-invalids.
TheotherplanetsandmoonsoftheSolarSystem,potentialsourcesoftheneededpull
ofgravity,arenotpromisingsitesforhumanhabitation.Marsistoocold,tooremotefrom
theSun,andhasathinatmosphere,mostlycarbondioxidewithapressureof1/100ofan
Earthatmosphere.Venusismuchtoohot,withasurfacetemperaturearound870(cid:1)Fandan
atmosphere of mostly carbon dioxide, with pressures of about 90 times that of Earth.
Moons,asteroids,andartificialspacehabitatsmaybebettersitesforhumancolonies,but
theyallhavelowgravityandotherproblems.TofindatrueEarth-likehabitat,weneedto
leavetheSolarSystemfortheEarth-likeplanetsofotherstars.
But if escaping Earth’s gravity well is difficult, travel to the stars is many orders of
magnitude more difficult. Fairly optimistic studies presented at the recent 100 Year
Starship Symposium in Orlando, Florida, sponsored by DARPA and NASA, showed
conclusively that there was little hope of reaching the nearby stars in a human lifetime
using any conventional propulsion techniques, even with propulsion systems involving
nuclearenergy.Theuniverseissimplytoobig,andthestarsaretoofaraway.
Whatisneedediseithertrans-spatialshortcutssuchaswormholestoavoidtheneedto
traverse the enormous distances or a propulsion technique that somehow circumvents
Newton’s third law and does not require the storage, transport, and expulsion of large
volumesofreactionmass.Inshort,thepathwaytothestarsrequires“exotic”solutions.
ThisbringsustotheworkofJamesWoodward.Jim,armedwithathoroughtheoretical
groundingingeneralrelativityandaconsiderabletalentasanexperimentalphysicist,has
pioneered“outsidethebox”thinkingaimedatsolvingthepropulsionproblemandperhaps
eventheproblemofcreatingexoticmatterforwormholesandwarpdrives.Hisworkhas
included investigations in general relativity as applied to Mach’s principle and experi-
mentalinvestigationsofpropulsionsystemsthatproposetocircumventthethirdlawneed
Foreword ix
toejectreactionmassinordertoachieveforwardthrust.Thislineofinquiryhasalsoledto
aplausiblewayofsatisfyingtheneedfor“exoticmatter”toproducewormholesandwarp
drives.Thebookyouholdmayofferthekeytohumantraveltothestars.
Let’s consider the problem of reactionless propulsion first. Woodward extended the
workofSciamaininvestigatingtheoriginsofinertiaintheframeworkofgeneralrelativity
by consideration of time-dependent effects that occur when energy is in flow while an
object is being accelerated. The result is surprising. It predicts large time-dependent
variations in inertia, the tendency of matter to resist acceleration. Most gravitational
effects predicted in general relativity are exceedingly small and difficult to observe,
becausethealgebraicexpressionsdescribingthemalwayshaveanumeratorthatincludes
Newton’sgravitationalconstantG,aphysicalconstantthathasaverysmallvaluedueto
the weakness of gravity as a force. The inertial transient effects predicted by the
Woodward–Sciama calculations are unusual and different, in that they have G in the
denominator,anddividingbyasmallnumberproducesalargeresult.
Woodwardhasdevotedmanyyearstodemonstratingthattheseinertialtransienteffects
exist, and recently he has been able to demonstrate tens of micronewton-level thrusts
delivered to a precision torsion balance, effects that show the correct behavior in the
presenceofvariationsandreversalsoftheexperimentalparameters. Thelatest resultsof
thisworkhavenotyetbeenpublishedinpeer-reviewedphysicsjournalsorreproducedin
other laboratories, but nevertheless they represent convincing evidence that
Woodward–Sciamainertialtransientsarearealphysicalphenomenonandthattheunder-
lyingcalculationsbehindthemshouldbetakenseriously.
Thepropulsioneffectsobservedsofararequitesmall,butnotsosmallastobeuseless.
Some of the ionthrusters employed by NASAfor long-duration space missions produce
comparablethrusts.Further,becauseoftheG-in-denominatorandtheirstrongfrequency
dependence, the inertial transients can inprinciple produce verylarge propulsion forces.
Developing Woodward–Sciama units that operate large volumes of inertia-varying mass
athighfrequenciescould,inprinciple,producemacroscopicthrustandlift.Personalflying
cars and reactionless heavy-lift Earth-to-orbit space vehicles cannot be ruled out if such
technologycouldberealized.
But perhaps the most interesting Woodward–Sciama inertial transient is the “second
term,”whichisalwaysnegativeandcaninprinciplebeusedtodrivetheinertialmassto
zeroornegativevalues.Ascarefullyoutlinedinthebook,thiscould,withabitofluckand
clever engineering design, be used to provide the “exotic mass” needed to stabilize
wormholesandproducesuperluminalwarpdrives.
WhenIwasstudyingphysicsingraduateschool,thecalculationsofgeneralrelativity
weredonebyhypothesizingaconfigurationofmassandthencalculatingthe“metric”or
distortionofspacetimethatitproduced.Thisapproachhasledtomanyinterestingresults,
butnonethatcouldbeconsidered“exotic”or“unphysical.”Butthereisanotherwaytodo
such calculations in general relativity, an approach that has been labeled “metric engi-
neering.” One specifies a spacetime metric that will produce some desired result, for
example, a wormhole or warp drive, and then calculates the distribution of masses that
wouldberequiredtoproducesuchametric,withallitsconsequences.Generalrelativity,
used in this way, had suggested the possibility of wormholes, time machines, and warp
drivesthatcouldtransportalocalmassatspeedsfarfasterthanthespeedoflight.
x Foreword
Manyofthetheoreticalphysicistswhoworkwithgeneralrelativityhavefundamental
objections to the very idea of wormholes and warp drives, which they consider to be
unphysical. Some of them have decided that one should erect a “picket fence” around
thosesolutionsofEinstein’sequationsthatareconsideredtobephysicallyreasonable,and
to place exotica such as stable traversable wormholes, faster-than-light warp drives, and
time machines in the forbidden area outside the fence, excluded because it is presumed
thatnaturedoesnotallowsuchdisreputableobjectstoexist.Theyare,ineffect,attempting
todiscovernewlawsofphysicsthatwouldplacerestrictionsonGRsolutions.
Their first attempt at building such a fence was called the Weak Energy Condition
(WEC). In essence, the WEC assumes that negative energy is the source of “problems”
withGRandrequiresthatforallobservers,thelocalenergyinallspacetimelocationsmust
be greater than or equal to zero. In other words, if any possible observer would see a
negative energy, that solution of Einstein’s equations is excluded by the WEC. A less
restrictive variant of the WEC is the Average Weak Energy Condition (AWEC), which
requiresthatwhentime-averagedalongsomearbitraryworldlinethroughalltime,thenet
energymustbegreater than orequaltozero,sothatanytime period whenthe energyis
negativemustbecompensatedbyaperiodofpositiveenergy.
TheWEC,AWEC,andtheothersimilarenergyrulesare“made-up”lawsofnatureand
arenotderivablefromgeneralrelativity.Theyappeartobeobeyedforobservationsofall
known forms of matter and energy that do not fall within the domain of quantum
mechanics. However, even for simple situations involving quantum phenomena
(examples: the Casimir effect, squeezed vacuum, and the Hawking evaporation of black
holes),theWECandAWECarebothviolated.
Morerecently,certainquantuminequalities(QI)tobeappliedtowormholesandwarp
driveshavebeenderivedfromquantumfieldtheory.Basically,onechoosesa“sampling
function,” some bell-shaped curve with unit area and width T that specifies a particular
restrictedregionoftime.Thisfunctionisthenusedwithquantumfieldtheorymethodsto
average the energy per unit volume of a field within the time-sampling envelope and to
placelimitsonhowmuchnegativeenergycanexistforhowlong.
The QI are bad news for would-be practitioners of metric engineering. Taken at face
value,theQIsaythatstablewormholesmaybeimpossibleandthatawarpdrivemight,at
best, exist for too short a time to go anywhere. While a wormhole might wink into
existence during the short time that the negative energy is present, it would wink out of
existence again before any matter could pass through it. It appears that within the QI
conditions,whennegativeenergyiscreated,itiseithertoosmallinmagnitudeortoobrief
indurationtodoanythinginteresting.
However, it is not clear whether the techniques outlined in this book for employing
inertiatransientsaresubjecttotheQIlimitations.Further,therearereasonstothinkthat
quantum field theory cannot be trusted in its application to the field-energy situations
envisioned by the QI calculations. Quantum field theory must be wrong, in some funda-
mental way, because it attributes far too much positive energy to spacetime itself.
The density of “dark energy” deduced from the observations of astrophysicists
investigatingTypeIasupernovaeandthespace-frequencystructureofthecosmicmicro-
wavebackgroundisabout6.7 (cid:3) 10(cid:4)10Jpercubicmeter.Thesamequantity,ascalculated
by quantum field theory, is about 1040 J per cubic meter. Thus, quantum field theory