Is Gravity Control Propulsion viable? Part 1

In 2013 the answer is no. It seems that our reliance on chemical rocketry to get hardware into orbit will be with us for a long time to come. Private space companies are making Low Earth Orbit more accessible and cheaper however the fundamental high cost of launching hardware into orbit (between $20000/Kg to $50000/Kg depending on the launch platform) with its limitations for deep space exploration and restrictions to small payloads will still be there. Getting hardware out of Earth's gravity well only 150 Km above the surface requires vehicles with high thrust (rockets) which can expel large amounts of energy in a short period of time to overcome Earth's relentless gravitational pull. Rockets provide enough escape speed (11.2 Km/s) to reach a stable orbit. The alternatives outlined in a previous post ie the space elevator, external nuclear pulse propulsion and the Skylon Project all have some shortcomings. As usual funding is a big problem for research and whether they one day come to realisation seems to depend on economics,  politicians or the profit potential for private investors.

Can we one day replace rockets with an alternative (less expensive) propulsion method? (Photo: NASA)

 

Been looking at other alternatives such as Gravity Control Propulsion. If the weight problem can be reduced or eliminated altogether then this would change things. This would be a game changer for space exploration but is the concept viable or simply fantasy? Physics at the moment tells us that there is no means to shield an object from gravity or even control gravity for propulsion purposes. In a scene in the latest StarTrek movie, the Enterprise is built on the ground in a shipyard. This solves many problems with cost and practicalities of building the starship instead of assembling it together in space, however one begs the question: when the starship is finished, how do they get this big chunk of hardware into orbit? In the StarTrek universe, have they found a means to circumvent the effects of gravity? In the movie one doesn't see the crew floating around on the bridge of the Enterprise when galloping the galaxy as well, have they developed a means to create artificial gravity deck plating? Recreating Earth's gravity environment in the Starship is important, it solves many health issues for the astronauts who would otherwise be exposed to a zero-gee environment for long periods, not to mention doing basic tasks easier (space radiation exposure is another problem I won't discuss here). 

 

Can a Starship be built and launched from the ground? (Photo: StarTrek)

Mastery of Gravity Control Propulsion implies a deep understanding of the physics of gravity and the origin of weight on mass. So where are we up to? We have General Relativity, all experiments agree with it so far. Problem is GR explains very well how mass moves in spacetime but not the why. It is not a quantum theory of gravity and currently there are no such proven models. More specifically it does not explain for eg the dynamics of the quantum vacuum near mass and how mass interacts with the dynamic quantum vacuum. Why does mass affect spacetime? These are some of the questions that need to be answered. Closely related, what is the origin of inertia? Is Mach's principle a local or universal effect?

 

Let's have a look at several papers that touch on these topics starting first with Marc Millis on  Assessing Hypothetical Gravity Control Propulsion. The paper refers to hypothetical gravity propulsion as a propellantless vehicle which can manipulate gravity, inertia or spacetime. The primary goal is to eliminate the need for propellant to get the vehicle into orbit. A space drive is defined as "an idealised form of propulsion where the fundamental properties of matter and spacetime are used to create propulsion forces anywhere in space without having to carry and expel a reaction mass". The space drive would convert potential energy into kinetic energy for this purpose. The paper also compares the energy efficiencies of the hypothetical space drive compared to the conventional rocket equation, these are very preliminary calculations. It is noted that rockets can only levitate (hovering with no change in altitude) an object for a short period of time until their propellant runs out. The ability of a vehicle to hover indefinitely would be a big advantage. So Marc has outlined what is meant by hypothetical gravity propulsion. The elimination of the need for propellant is the big advantage here.

So in 2013 are there any loose ends in General Relativity? According to Schiller's Strand Model of Physics which looks promising, one of his many predictions include "No deviations from special or general relativity appear for any measurable energy scale. No doubly or deformed special relativity arises in nature." Let's have a look at the paper from Orfeu Bertolami et al. on General Theory of Relativity: Will it survive the next decade? Yes. However several interesting comments are made. It is mentioned on p2 "Even at the classical level, and assuming the Equivalence Principle, Einstein’s theory does not provide the most general way to establish the spacetime metric." This is an important point which we'll come back to later. Note the Equivalence Principle ie freely falling bodies have the same acceleration in the same gravitational field independent on their compositions (second important point we'll come back to later) which means a feather and a cannon ball for eg dropped in a vacuum will touch the ground at the same time, watch this video. It is also mentioned that GR does not provide an understanding how gravity should be described at the quantum level. Many researchers are concentrating their efforts on a unified theory of Physics that would include the electromagnetic, weak and strong interactions with gravity. Currently Quantum Field Theory fails in strongly curved spacetime metrics (ie where GR is applicable) while GR only works when Planck's constant (Quantum Field Theory) is ignored. The two models when considered separately work very well though at describing Nature on the large and small scales however concepts such as warp drives and wormholes for eg which are allowed in GR are denied by QFT (more specifically the physics of the quantum vacuum see Vol 5 p116 of Motion Mountain). The paper goes on to describe the many solar system wide experiments that have been carried out that confirm GR to great detail.

Section 3.4 deals with the interesting concept of gravity shielding. An earlier paper by Majorana in 1920 suggested the introduction of a screening or extinction coefficient, \(h\) to measure the shielding of a material of density \(\rho\text{(r)}\) of the gravitational force between two masses which can be modelled as follows
 

$$F'=\frac{G\, m_{1}\, m_{2}}{r^{2}}exp\left[-h\int\rho\text{(r) dr}\right].$$

There is currently no avenue in physics to derive \(h\), the gravitational shielding constant, without violating the equivalence principle and there are no materials known that would affect this coefficient. According to the paper the modern laboratory constraint is currently set at  \(h\leq4.3\times10^{-15}m^{2}kg^{-1}\). So is gravitational shielding a dead concept? It appears that no materials regardless of their density or composition will do the job, we'll get back to this topic in Part 2. The rest of the paper looks at other cosmological studies to confirm GR, alternate models of gravity and talks about dark matter (made of conventional matter and black holes surrounding galaxies) and dark energy (vacuum energy).

 

In the next post I'll look at a few more interesting papers and further thoughts on Gravity Control Propulsion.

CI.

Nuts and Bolts

Hi everyone,

There's a very interesting ABC radio interview available online titled The future of Interstellar Travel worth a listen. Various issues are talked about including getting Helium-3 for future fusion reactors and the challenges involved for interstellar travel.

Interesting post on Centauri Dreams regarding Icarus Interstellar. Impressive list of projects they got going. Myself I think it is 100 years too early to start designing starships in 2013 especially since we currently don't have a working industry grade fusion power plant let alone a flight ready version to put on a starship. However the two projects they have listed ie Project Bifrost and X-Physics Propulsion & Power Project  are worth pursuing now. I stopped looking at warp drives and wormholes last year. Although the field equations in General Relativity do have solutions that allow these spacetime curvatures, GR doesn't take into account the properties of the quantum vacuum and isn't a unified model of Physics. The solutions are not realistic in nature and are purely interesting exercises in GR. As for extracting energy out of the quantum vacuum, there are currently no mechanisms to do this.

Another interesting SBS article: Space: the mining frontier. Seems like space mining is making more headlines these days. Interesting issues raised include who owns the Moon, Mars, Asteroids etc and their minerals? Free for all who can afford to develop the space mining infrastructure? No doubt the UN needs to start developing some kind of legal framework as the private space sector is catching on. I wouldn't hold your breath though, one should remember that the International Space Station cost $150bn to build and this is in low earth orbit.

CI. 

Titan descent movie

Saw this on APOD, what a great movie!

Book Review: Deep Space Propulsion

Recently finished reading Deep Space Propulsion - A Roadmap to Interstellar Flight by Kelvin F. Long, 2012. A book review has already been written here so won't duplicate however will comment on a few points made in this excellent introductory text.  A rundown of current known propulsion schemes is given outlining their pros and cons for interstellar flight ranging from electric and nuclear based propulsion, solar sails, beamed power, nuclear fusion and external nuclear pulse propulsion, antimatter etc. Projects Daedalus and Icarus are also mentioned.

 

 

Some interesting points I picked up while reading the book:

Seven key motivations for interstellar travel are given:

 

Continued survival ie the ability of humans to survive on another planet would greatly increase our prospects for long term survival and also makes the point that while some suggest we should be focusing inwards on our problems on Earth and remain home  the author's reply to this is "These attitudes will only lead to one result: stagnation and regression of the human race" which I agree with. If one looks back in history some of those nations that went to the trouble of building ships to explore new worlds are fairly well off financially and increased our knowledge base (scientifically and culturally).

Balance of resources given the rate of population growth there will be a breaking point as far as the need for resources to sustain the future population unless more resources outside earth are found. When a nation runs out of critical resources they either buy more, take it by force or perish.

Economic opportunities ie plenty of money to be made by mining asteroids etc. Very rare minerals/metals required for certain key technologies on Earth may be in abundance in other places in our solar system.

Quest for knowledge ie Are we alone for eg? How many Earth like planets are there within 50 ly from Earth for eg? Astronomy / AstroPhysics / Universe etc

Spreading of life

Freedom factor

Starstuff driver ie the atoms in our bodies were made in stars and the author hints that we have a longing to return to what created us.

 

Another interesting point made by the author: "Any material that is launched into Earth orbit will cost typically around $50000 / Kg." This needs to be reduced substantially for any large scale space exploration. The current alternatives to chemical rockets are:

 

 The space elevator: feasible however the technology to mass fabricate the Earth to Orbit cable using high strength carbon nano-tubes is not in place (steel wire cable won't do the job).

 

 Project Orion: (external nuclear pulse propulsion): the energy release from nuclear reactions is of the order a million times greater than that from a typical chemical reaction making this vehicle a feasible alternative to chemical rockets. However detonating nuclear bombs in earth's atmosphere to get the vehicle off the ground leaving a radioactive trail behind isn't a good idea.

 

 Skylon Project: although this proposed spaceplane still would use a liquid oxygen/hydrogen rocket to reach orbit it is worth a mention because this is a step in the right direction as far as reducing the cost of getting hardware into orbit is concerned however not the breakthrough solution I am after (ie an elegant non-chemical propulsion solution).

All in all a good introductory text worth a read, has nice colour pages of the various designs talked about in the book.

CI.

Dampier, WA with Red Dog.

 

Some thoughts for 2012

Haven't posted for a while so better put something up! Wishing everyone clear skies and smooth waters for the year. What is the difference between Mathematics and Physics? Picked up this interesting quote which is food for thought:

"We are able to demonstrate geometrical matters because we make them; if we could prove physical matters we would be able to make them".  

Giovanni Vico (1668-1744).

What's happening with Propulsion Physics and where are we going? Is Interstellar Travel going to happen sometime soon? Several interesting papers were published in 2011 and the 100 year Starship conference went ahead however don't see them leading to a breakthrough anytime soon. Several key technologies such as fusion reactors need to be in place before the propositions in the papers can be turned into a Starship so one might have to wait at least 50 years, Marc has his wonderings on a possible future timelime here. It appears that the Universe as we understand it with our current models is not human friendly as far as practical interstellar flight is concerned although the Physics doesn't deny us Interstellar Travel, it appears that one needs to be prepared for the extreme challenges of distances and time required to travel to possible nearby Earth-like planets in our Galaxy.

If Schiller's Strand model for eg turns out correct, then it looks like Physics is close to being complete which would make it even more difficult for Breakthrough Propulsion Physics. Between work, I am pursuing my studies for 2012 in Quantum Vacuum Physics & Engineering and see where it leads. The other big problem is getting large amounts of hardware into orbit without using chemical rockets. Is there a viable solution without using space elevators?

Some recents photos taken when I was recently in Exmouth, Western Australia. Most interesting sites are the US Navy VLF transmitter for submarines and the Learmonth Solar Observatory. Didn't see any turtles laying eggs on the beach, they turn up at night.     

CI.

Local Exmouth resident.

Vlamming Head Lighthouse.

Navy VLF station in the distance.

Closer view.

Checkout the Sydney outline diagram!

An interstellar position fixing method

Paper is now available for download at:

http://vixra.org/abs/1106.0053

CI.

Nuts and bolts

It has been an interesting start of the year for 2011 with some recent items worth mentioning:

Marc Millis of the Tau Zero Foundation posted two papers related to interstellar flight:

Progress in revolutionary Propulsion Physics: summarises the current state of where we stand towards a solution? for "timely interstellar flight - to reach other habitable worlds within a human lifespan". There are currently many options available to reach other stars using known physics. Most would take many decades just to reach our neighbour stars and none of them can get us to destinations beyond many light-years away in a timely, human lifespan timeframe. The paper uses many references from the first recent textbook devoted to this area of research and is worth every dollar: Frontiers of Propulsion Science. I like Figure 1 in the paper which graphically shows the many areas of Physics and concepts that need further research grouped by the key barriers to practical interstellar flight as stated in the paper: Non-propellant propulsion, faster than light travel and energy breakthroughs.

Second paper by Marc: Energy, incessant obsolescence, and the first interstellar missions: there's a review here. Regarding the "incessant obsolescence postulate: No matter when an interstellar probe is launched, a subsequent probe will reach the destination sooner and with more modern equipment": better launch as soon as one has the capabilities to do so because the opportunity may not present itself again due to unforseen circumstances in the future or "societal retardation" ie unforseen catastrophies or less energy production. The implicit motivations for interstellar flight, Table 6 in the paper is interesting, apart from the obvious scientific benefits from the mission and safeguarding humanity's long term survival, I liked another reason that Marc mentions in his talk to pursue interstellar flight: it gives nations something to conquer peacefully and together rather than concentrating on conquering each other on Earth.

Significant results released by the Kepler space telescope shows possible candidates for other Earth like planets. From the NASA press release:

"The fact that we’ve found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting stars like our sun in our galaxy," said Borucki. "Kepler can find only a small fraction of the planets around the stars it looks at because the orbits aren’t aligned properly. If you account for those two factors, our results indicate there must be millions of planets orbiting the stars that surround our sun."

Also checkout APOD, Centauri Dreams, this and this.

Got in the mail a few days ago: Advanced Propulsion Systems and Technologies, Today to 2020. Another major problem to practical interstellar flight is getting the expected large amounts of hardware out of Earth's gravity well into orbit without using chemical rockets. Space elevators have been proposed (which seems only viable if ultra high strength carbon nanotube cables can be commercially fabricated in the required lengths). A more elegant solution? from Space Drive Physics is worth looking into (see Marc's first paper for an introduction, Chapter 3 Prerequisites for Space Drive Science and Chapter 12 Thrusting against the Quantum Vacuum in Frontiers of Propulsion Science). Anyway should be an interesting read.

CI.

Fremantle Harbour, Western Australia.

Dampier Harbour, Western Australia.

Book Review: And Yet It Moves

Today I finished reading And Yet It Moves: strange systems and subtle questions in Physics by Mark P. Silverman. I found this book particularly interesting as it introduced me to quantum phenomenon which previously weren't very familiar to me. The author being a research physicist has first hand experience with the topics he discusses. Several experiments are descibed including the wave like propagation of electrons in the two-slit experiment describing the familiar wave interference effect and the Aharonov-Bohm effect and other subtle behaviour of electrons. To me the nature of this particle is somewhat still not understood. Some texts for example will describe the electron as point-like as today's experiments give no measurable size of this particle (the classical electron radius is given as 10^-13 cm), however there is no such thing as a point-like entity (and no such as thing as a mathematical singularity in nature for that matter which rules out infinities as well, the Universe is not infinite) so suffice to say the electron must have a size albeit very small and unmeasurable with current technology.

The author goes on to describe some exotic atoms describing some which can be nearly the size of bacteria!, the physics of light reflections, light polarisation, the Mach-Zehnder interferometer, the amazing (check this out!)  Vortex Tube and other interesting subtle effects. The author asks on p204:

"Can the rotation of the Earth influence the structure of an atom?"

And goes on to discuss biomolecular chirality ie why living things make and use specific types of molecules such as right-handed sugar molecules or left-handed amino acids (this isn't understood, Earth evolutionary reasons?). The last chapter "Science and wonder" gives a personal account on various issues with science education, from the last page:

"To teach science well, one must have the philosophical attitudes of a scientist: to see science as culturally important, technically useful and aesthetically moving; to understand that the pursuit and acquisition of scientific knowledge helps free the mind from the bondage of ignorance, superstition and prejudice; to have a driving curiosity to comprehend the reason that manifests itself in nature and to enjoy sharing this curiosity with others.

  Einstein's eloquent words say it all:

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. He who knows it not and can no longer wonder, no longer feel amazement, is as good as dead, a snuffed-out candle."

Great book, definately recommend reading it, got me chasing up some of the references at the back as well.