Monday, December 6, 2010

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.

Wednesday, December 1, 2010

Red Bull Flugtag 2010 photos


A few weeks ago we had the judges onboard for the Red Bull Flugtag event in Farm Cove near the Sydney Opera House. Those crazzy people with their flying machines were at it again! It was a nice sunny day and there was a good turnup with the crowds and boats.

One of the teams made quite a long flight (it was pretty much a standard flying kite though, no exotic design). Most just fell straight down off the ramp to see their flying machine broken into bits and pieces. The judges gave scores to each team for design, asthetics etc.

After the crew are rescued by Surf Rescue, what happens to these flying machines?

Although few teams have demonstrated their mastery of flight, it was a fun day out on the water.


Saturday, November 13, 2010

A day out on a 100 tonnes mobile slewing crane

I recently finished a course at Botany Cranes to get a WorkCover 100 tonnes mobile slewing crane licence (for work reasons on boats). Because I was the only one in the class, they sent me with one of the crane drivers for a day for a dual lift job to see first hand the operations of the crane and get some dogging experience. I thoroughly enjoyed the course and more importantly passed the big test at the end. The crane I went on was a Liebherr 100 tonnes crane who make some of the best cranes in the world. The other crane that came with us was the 130t crane. A support truck and crew is also needed for the cranes to carry additional hook blocks, counterweights, packing for the outriggers etc.

Leaving the yard from Botany Bay our destination was the P&O container depot near Bankstown to put together an Omega Megastacker crane (brand new) which is used to lift and move shipping containers.

The Cranes

The job

After a toolbox meeting with the other crew, the cranes are parked into position and outriggers for the cranes extended to maintain stability of the crane during lift. Timber packings are used under the outrigger pads to spread the weight of the crane over a larger surface area onto the ground. All the wheels of the crane must be above ground and the crane dead horizontal. There is an electronic equivalent of a spirit level which makes this process fairly straightforward.

Setting up the outriggers

The crane operator will decide what hook blocks are required for the job, what hook radius he will be operating (and hence how much boom needs to be blown out) and more importantly how much the load mass with all lifting gear such as spreader beams need to be included. The crane operator reads the Load Chart for the crane which gives all this important information and will decide how much counterweight needs to be placed at the rear of the crane. All these factors will dictate what the maximum load the crane can lift for those parameters. With the boom fully extended, this crane would tip over if the operator forgets to place counterweights on the crane. The Liebherr cranes have an onboard computer which also makes all this process straightforward and safe (we don't want the crane to be tipping over or brake the $2.5 mil crane!). The more the boom is blown out or the more the boom is lowered for a given boom length, the less the crane can lift.

After unhooking the hook block at the front of the crane and setting up the counterweights, the crane operator blows out the necessary boom sections. Everything is hydraulically operated and one selects from the computer screen how much boom we want. Two heavy hauler trucks turned up with the Megastacker's boom and arms, nice $20000 paintwork!

The first truck looks like a Transformer in disguise? ;-)

After both cranes are setup and the truck with the first part of the Megastacker in position, the dogmen setup the chain slings required for the job. One person will direct the crane operators for the dual lift job. This is a delicate operation and both cranes need to work together so no extra stress is placed on the cranes and lifting gear. The first part of the job required the boom section of the Megastacker to be placed into position so the Omega technicians could pop in the holding pins for the boom. Once this was done hydraulic rams needed to be lifted and bolted on both sides. The position of the boom had to be in perfect alignment otherwise the pins wouldn't go in.

Putting the million dollar Megastacker together

After the boom section and rams were secured, the next part of the job was to lift and attach the grabber (which grabs and locks into the containers). This was also a delicate operation. Hydraulic rams needed also to be lifted and bolted into position.

The grabber section for the Megastacker
By late afternoon the job was finished and it was time to pack up the gear and stow the cranes for road travel. Because of the tare weight of these cranes, they aren't allowed to travel on some bridges (including Sydney Harbour bridge), tunnels etc so he needs to have a good read of a street directory to decide what is the best route to get to and from a job. We make it back to the Botany Cranes yard after heavy traffic on the main roads. With all the construction that goes around the city, the other cranes are also out doing jobs.

So there you go, great day out and learnt a lot. If you want to see how big these cranes get, checkout the Liebherr 1200 tonnes mobile slewing crane! (Other crane types get even bigger). Doing the Dogman course at the moment (at another school because of timetable reasons). A Dogman is the person who slings the loads, directs the crane operator etc, big test in a few days so better get back to studying! Till next time.


Monday, November 8, 2010


Got a visit in the wheelhouse yesterday by Caricaturist Gavin Bell during a cruise in Sydney Harbour (Red Bull Flugtag event photos coming soon). Here it is!

Saturday, October 16, 2010

Voyages to Lord Howe Island

It's been a while since I've updated my blog, been a bit busy with work/new job/studies etc.

Started working on the general cargo vessel MV Island Trader the last several weeks. Doing my 4th trip this coming week. Lord Howe Island is just over 300nm East of Port Macquarie, NSW. The boat delivers everything that a small community of 300 + 400 or so tourists need on the island including diesel for the island's power station, petrol, LPG, A-1 jet fuel for the airport, frozen and refrigerated goods, building materials, cars/trucks, mail and all kinds of other general cargo. The Island Trader departs Port Macquarie usually every second Thursday and on the return trip picks up garbage, return mail, empty fuel drums etc from the island for disposal back on the mainland. A one way trip takes just under 2 days.


The previous day and on the day of departure, the derrick cranes on the boat and forklifts are getting a good workout loading the cargo onboard, crew secure all cargo and make sure everything is well strapped in. Final drafts of the vessel are taken, stability calculations done, cargo gear stowed and secured, final checks done, we then wait for the next high tide to leave port. Leaving the wharf which is a few Kilometers up the Hastings River near the Pacific Highway, we venture downstream past the two cable car ferries that service the Port Macquarie area further down from Dennis Bridge.

Getting to Lord Howe Island is pretty easy, after crossing the bar at Port Macquarie head East and eventually you'll get to the Island. From the island head dead West 270° T to get back to Port Macquarie. There can be busy shipping traffic near the coast but once clear of the coast there is very rarely any vessels in sight after 50nm.

During the trip I typically do regular 4 hour watches on and off as Officer Of the Watch (OOW) in the wheelhouse. The boat is on autopilot so I'm not actually steering the boat in the above photo ;-) however minor course corrections need to be regularly made as the autopilot steers by the steering compass. According to the GPS, our speed over ground is usually around 8Kn however sometimes the ocean currents will make us go slower or faster for our given engines RPM and our SOG can vary from 6.5Kn to 12.5Kn (record so far), big difference! This can affect our ETA to the island significantly to the point where sometimes we can miss the high tide or we would arrive too early which in this case we would slow down during the last leg. There are quite a lot of sea birds visible along the way as well including Albatrosses. Close to the coast we saw the usual migrating whales and dolphins.

Our destination at the island is the wharf constructed in front of the site which used to be the island's flying boat airport terminal when flying boats used to provide regular flights to the island from Rose Bay, Sydney. The island now has a 1Km runway and Qantas provide usually 3 flights a day out from Sydney, Port Macquarie and Brisbane using Dash-8s.

The wharf is inside the lagoon on the western side of the island which is surrounded by reefs however there is a narrow passage for vessels to enter the lagoon marked with transit leads and sector lights. To get to the wharf we also need a high tide and the Lord Howe Island Harbour Master will give us a reading of the current tide at the wharf via VHF radio as the current tide readings can vary depending on weather conditions (such as barometric pressure) compared to predicted tide table readings.

Getting through the channel can get a bit hairy when the sea is a bit rough and the Captain (Master 3) who has lots of local knowledge will decide whether to enter or not. If conditions are too rough to make an entry, the boat can either do circles around the island or drop anchor at a sheltered location till things settle down. Once inside the lagoon the waters are usually pretty calm however at high tide big waves can still go over the surrounding reefs and cause surges in the lagoon.

Once secured at the wharf, the Engineer will start emptying the ballast tanks so the boat sits at the bottom, this makes it safer for cargo unloading however even then one has to be careful with the derrick cranes as at high tide the boat can still surge a bit. There can be quite a large crowd at the wharf apart from the wharf crew, tourists turn up to check out all the maritime action. It will take the rest of the day and the next day to unload all the cargo with the help of the wharf crew who live on the island. Supplies and goods are then delivered to their destinations by several trucks that go throughout the island. The Captain was kind enough to let me off so I could hop on one of the trucks to get a sightseeing drive of the island on my first trip.

The boat usually stays at the island for a couple of days. During those days it's very busy as after all the cargo is unloaded, there is the back load cargo to be taken onboard, stowed and secured. However sometimes we finish a bit earlier in the afternoon and on one trip managed to go for a walk to some other areas on the island. Ned's Beach which is on the eastern side of the island was interesting with big King fish swimming around my legs when I was feeding them nibblies. I also introduced myself to the local cows and went hill hiking to get a better view of the scenery:

There are many resorts on the island and tourism is the main revenue maker and the export of the local Kentia palm tree seeds which is native to the island. There are a few boats that also do diving, fishing and sightseeing trips to Elizabeth and Middleton coral reefs which are located 150Km north-east of the island. These are the southern most coral reefs in Australia. If you venture at night to have a beer at the local bowling club, bring a torch with you because there are no street lights (which is great because you can see the Milky Way, should have brought my telescope with me ;-) There is no mobile phone reception on the island however there is a Telstra public phone available and we can watch TV onboard when we are at the island.

The back load is usually light, skip bins full of garbage, recycled plastic etc, lots of empty 200L A-1 jet fuel drums, empty LPG tanks and IBCs (Intermediate Bulk Containers) for petrol and other stuff. I'm told that the airplanes that land at the island have to always refuel in case they can't land back at their destination and have to be diverted so no one wonder they go through a lot of fuel drums.

Heading back to Port Macquarie is pretty much the same routine with watches and I'm finding sleeping in the bunk with the boat rolling side to side relaxing however the trips that I've done so far haven't been that rough. One of the deckhands onboard cooks dinner for the crew every day and he's a pretty good cook too. The most relaxing part of the job is while we are at sea as in port things get busy and this gives me a chance to catchup on my readings.
On the second day of the return sea voyage we also do an emergency drill such as Man Overboard, Fire drills etc and test equipment. After we are docked at the wharf back at Port Macquarie up the Hastings River all the back load is unloaded and we give the cargo hold and boat a good cleanup and any maintenance required on the cargo gear and boat is carried out. After signing off it's a 5 hour drive for me back to Sydney. Till next time.


Monday, April 19, 2010

More interesting technology

Been a bit busy with my studies so no long posts for a while but here's an interesting photo of a touch screen onboard a boat I work on as Engineer ;-)

Tuesday, March 23, 2010

New T3000 Marine Autopilot

Just can't keep up with technology these days, what will they think of next? ;-)

Sunday, February 14, 2010

Part 8: Book Review - Prospects for Interstellar Travel

In the final part of this book review series we look at the last chapter where the author gives his conclusions and further thoughts on many of the topics discussed so far and gives some assessments on how far it would be feasible to push technology and possible scientific breakthroughs needed: "If prospects for mastering the ultra-technical problem of interstellar travel in the near future seem somewhat discouraging, this chapter tries to show where we must try harder." so let's have a look.

In the search for better technology based on our laws and theories discovered so far, it is pointed out that: "Science consists partly of revolutions in understanding (e.g. relativity). More revolutions are needed to make interstellar travel easy, although laws of nature are not so much overthrown as refined." [CI: This reminds me of what Roger Penrose said in his book quoted below:]

Mauldin goes on mentioning that very few stones have been left unturned as far as energy sources go. Many of the topics discussed in the book are based on 19th century physics with relativity imposing refinements and limits to travel in the form of lightspeed and mass-energy for propulsion and the Standard Model doesn't appear to have any new undiscovered nuclear energy sources however it is expected that new materials and new uses of electromagnetic fields for eg. will allow progress in many areas such as the possibility of warm superconductors and fusion reactors.
[CI: Image: Example of a proposed reactor to study fusion: ITER.]

To understand Nature, theories are developed to help us describe her and to verify these theories experimental evidence is acquired to see if Nature agrees with them. Many theories are developed however few standup to observational evidence or experiment. [CI: a good quote from Planck below].

[CI: Photo: Our closest star the Sun, a natural fusion reactor.]

The author goes on to mention that: "Whether our science is slowing for lack of startling new evidence, or for lack of deeper, more clever human thinking, or from reaching final barriers inherent in nature cannot be determined. The situation is perplexing. Some would say that scientific progress continues to accelerate, not just applied science but basic science." It is also pointed out that as far as interstellar travel is concerned, this is partly an engineering problem and building a starship would involve assembling materials of the right size, with reliability, performance and cost. This may also mean pushing known materials to their limits. Several examples are then given with a discussion on the current state of affairs regarding superconductors, magnetic fields and materials sciences and their applications to previously discussed power systems, shields and solar sails. The author then mentions some of the current problems we face in science related to interstellar travel: 

"Scientifically, the crucial advances are needed first in physics. If powerful propulsion is developed, along with solutions to some of the operations problems, then biological, social, and economic problems of travel would eventually be solved. Those who study interstellar travel in a fascinating blend of fantasy and real physics have found a large number of different ways of getting there, almost all meriting careful theoretical study, none yet leading to affordable hardware even if scientists had ready access to space now. Unfortunetly, there is very little indication in general relativity or elementary particles of new higher energy sources, forces, or effects that could be used in propulsion. If there were, motion in the context of general relativity (curved space-time) would also merit more study and be part of this book."
[CI: Research is ongoing. Regular conferences are also held. For those who wish to study the propulsion aspects further, a  good starting point is: Frontiers of Propulsion Science. If you need to brushup on your physics try this free book, these free lecture notes and read this other free book while you're at it. Understanding the physics of the vacuum (and how it affects matter/energy and vice versa) may be an important step in making some progress in this area. Here are some interesting items to get started: 1, 2, 3. Regular news in this field can also be found from Centauri Dreams and keep an eye for the latest papers on arXiv and viXra. Here's a useful guide to sort out the crackpots.]

The author then discusses further the enormous energy requirements for interstellar travel and even with anti-matter  we still have the fundamental energy problem: "how to get more energy from less inertial mass." It is pointed out that some studies for eg. have looked into the vacuum with its varying amounts of fluctuating energy mostly as particle/anti-particle pairs and the possibility of harnessing these quanta of energy. Nature allows one to borrow energy without penalty provided this loan is over a very short period of time: "Planck's constant is involved and permits only very tiny effects [see Appendix D]. One could borrow 10^24 J, the whole KE requirement of a star journey, from space itself for about 10^-58 second, an inconveniently short-term loan." with longer time loans one could borrow smaller amounts of energy but for 1 J the loan period would still only be 10^-34 second and this quantum borrowing doesn't appear feasible however notes: "A way to cheat nature on this law is yet to be found. Perhaps it will be overthrown in some subtle, unforseen, dramatic way."

Other areas worth a look where the Stardard Model has left doors open include the possibility for a "false vacuum" field or Higgs field which is thought to be left over from the Big Bang and might be producing the masses for all particles by "resisting" their motion until they enter the TeV energy domain. The Higgs field would make itself known by its Higgs bosons over 1 TeV [CI: one of the goals of the LHC is to detect these particles] and the author gives a rundown of what we think of this Higgs field looking at the cosmological constant considerations and inflation theories. The author suggests further studies into the higher energy domains using space based accelerators may provide some solutions for interstellar drives and notes that: "space has many "vacuum" fields: gravitational, electro-magnetic, hypothesized false vacuum (Higgs), nuclear, and others that may be discovered. All should be ruled by the law of quantum physics in that the amount of energy that temporarily appears is determined by Planck's constant." Studies in the the electromagnetic field of the vacuum have also been ongoing with the Casimir effect. The force on the plates can be made to

[CI: Image: When two metal plates are a few micrometers apart, an attractive Casimir force develops due to an inbalance of the electromagnetic fluctuations in the vacuum between the plates.]

do work that is yield energy however no useful amounts of energy are expected to be extracted using this method. Some consideration is given to "Dark matter" and the author gives a rundown of what is and isn't known so far however notes that: "More discouraging is that the bulk of dark matter, if it exists, seems to be present not within galaxies but in intergalactic space where we cannot use it." All avenues for a possible "ultra-energy" source need investigating, this is directly linked to any future prospects for ultra-relativistic interstellar travel.

A discussion is then given on Back Holes and other interesting phenomena that follow from General Relativity that "greatly distort, disconnect, or connect space-time" such as hypothetical wormholes and whiteholes. Some studies have looked into the possiblities of using these unusual spacetime topologies for interstellar travel and all are highly speculative. The author notes that: "Black Holes are probably real although finding sufficient evidence to be convincing has been a major task. The nearest partly-confirmed one Cygnus X-1 is thousands of lightyears away." Approaching a black hole alone would be very dangerous because of the intense radiation due to infalling material and the large gravitational tidal effects ripping objects apart. Various authors have considered black holes as a possible power source for starships however these appear unrealistic.

Some mention is also given to so called "anti-gravity", "hyderdrives", "spacewarp drives" and Faster-than-light (FTL) ideas which are thought to be either physically unrealistic or highly speculative however notes that General Relativity as currently understood does not prohibit particles moving FTL locally but they cannot move slower than light, these hypothetical particles are called Tachyons. [CI: Many authors have written papers on various spacetime warping schemes  however  some authors have also shown that these may not be physically possible when one considers quantum effects as well. My point of view is that the highly distorted spacetime topologies are unfeasible when one considers quantum vacuum effects and are at best interesting exercises in General Relativity for considering the various solutions it can offer, not all of which can be used or are allowed in nature.]

In chapter 8 the author discussed the problem of space transport from the starship to the surface of the new planet and vice versa with a discussion of why this would be a problem as there would presumably be no facilities on the new planet (for shuttle launches for eg) and the use of chemical rockets for moving large amounts of materials and personel is expensive and unsuitable for planets larger than Earth (with a deeper gravity well) because of the large amounts of fuel (preferably hydrogen/oxygen) to be carried on the interstellar mission and this would need to be found at the destination. It is also noted that with new planets with an atmosphere, shuttles could glide their way to the surface however for some interesting airless planets these will require rocket landings (and probably would be deficient in fuel). Capsule landings via parachute are not recommended because they only carry small loads and are less likely to be reusable. Abundant hydrogen would still be required even if anti-matter provided the energy.

Mention is given to new designs of spaceplanes which were considered such as the Hermes however these may be difficult to design for unknown atmospheres. All the previous other ideas pointed out on non-rocket space launches (space elevators, launch tracks, balloon supported launches etc) also have their problems and notes that: "As with spaceplanes, most of these methods seem to use materials to their limits in strength, toughness, and/or integrity. At an interstellar destination, most of these involve massive structures which cannot easily be carried or built on site." It is also pointed out that: "At present massive emigration from Earth to local space seems impossible due to the cost and complexity of lifting just the people, never mind their equipment, into space. Transport using cables and the like would change that." It would be necessary to  build an extensive infrastructure in the local space environment (for fuel and structures) before landing people on the planet is considered.

[CI: Image: One alternative to using rockets on an airless moon or planet: shoot your
precious cargo off the planet using the eletromagnetic catapult concept?]

Some considerations are also given to the "wilder ideas" such as stronger materials using only neutrons (such as the closely packet matter in neutron stars where the electrons have combined with protons and notes that: "If neutrons did "touch" and bond, nuclear matter would be a trillion times stronger than ordinary everyday matter." and with physicists starting to collect very cold and slow neutrons in bottles the possibility could be explored.

Several interesting conclusions are then given by the author on the various topics discussed throughout the book and makes a note again that: "The key practical step toward the stars is propulsion, but technology is inseparable from purpose." and points out that a trend in the articles published on starship propulsion ideas seem to lean more and more towards lower speeds from the high gammas of 0.9c down to 0.1c (Daedalus) to 0.01c for some fusion drives. The author gives his assessment on propulsion on p303:

"The best guesses here for propulsion at present are sunbeam-pushed sail or pulsed fusion, with a separate braking system. Farther down the list because they are still slower are an ion-drive powered by a fusion reactor, or a solar sail using direct local sunlight."
and notes further along that: "shielding, artificial gee, operating power (especially if sails are used), and landing remain to be solved as discussed earlier." pointing out that a starship with no artificial gee is likely to deny the crew to land on a planet due to the permanent changes this would cause to their bodies.
Further conclusions on the sociopoliticial context are also given. It is pointed out that although there was initial great enthusiasm for the space age, progress has become very slow and: "public support and money seem to have diminished, although US NASA's budget increases year by year. Less and less is done, while some billions of dollars are spent on mistakes." and further along asks:

"Political problems aside, is this the trend of our future in space, less and less over longer and longer time, with perhaps bigger confusion and failures? Have we reached technical limits already? Delays on new propulsion would seem to corroborate this... A yet unimagined drive would drastically change the situation."
It is also pointed out by the author that over the several chapters, many great problems were presented and this all might seem discouraging to future prospects for successful interstellar missions:

"the difficulty of determining a habitable destination before going there, the difficulty of returning, the long ordeal of many generations traveling to a near star, the hazards of breakdowns, radiation, and zero gee, the long time commitment to find out if a mission yields results, and the lack of visitors here who have accomplished such travel. But it is too early in our social and technological history to draw final conclusions about this futuristic goal, and no single paramount conclusion can be presented here. To reach the expected scientific and technical adventures and achievements, we simply may need to try harder."
Given the expected enormous costs of an interstellar mission (given at 100 T$ upwards for a 100 person mission), the author gives his point of view of why interstellar travel should be pursued despite the costs and great technical difficulties:

"The energy, environmental, and monetory costs of launch from Earth already seem almost prohibitive. Some say that we can no longer afford space, that we must work on problems of population control, environment, energy, housing, education, equality, crime, and health at home. Even if these problems were fully and cooperatively addressed, one should still ask, toward what end? Is this all a young civilization can do for the rest of its time, try to hold onto a high quality of life for some and establish a mediocre but adequate quality for the rest? Restricted to one planet, humans at most can try for an ecologically stable or "sustainable" set of "lifestyles", more complex, based on different economics, probably more austere than present varied styles. At best, a garden planet with a lower stable population would result. New frontiers in space can provide direct and symbolic outlets for untamable instincts, places for adventurers to fulfull themselves and initiatives for homebound populations to support at modest levels."
and also makes several conclusions based on human nature as it appears now.  Contrary to what is portrayed in science fiction, because of the many difficulties mentioned earlier, very few people would actually get to travel to the stars and interstellar travel cannot also be used to "save" Earth.  Sending any useful practical results back to Earth could also take centuries (if one considers a 1000 year mission) and hence interstellar missions would be very difficult politically to implement and most people would have forgotten of the mission over time however: "While the problem of interstellar travel is closely intermeshed with our future, it is an open question whether we can expect a study of interstellar travel to make a difference in the general human condition."

The author concludes by mentioning that the goal of his study and review on interstellar travel was: "to leave the case in the hands of present and future readers with a wide range of interests and let them judge what the prospects are now and later. All options should be set out for contemplation and planning... Interstellar studies as a complex branch of science and technology could serve as one of many inspiring vehicles to teach the spectrum of sciences and applied math, to introduce systems and design, to teach integrated and creative thinking, to show the interaction of technology and society, and much more. Grasping and exploring the problem can engross a student for years. Education in the broadest ways possible is one key to a future that permits interstellar missions."

[CI: In the Appendix sections of the book, the author gives a concise summary of classical physics and relativistic travel with an explanation of the physics behind the various concepts discussed in the book with more detailed mathematical treatment and numerical output tables of the included BASIC programs comparing various values of acceleration, time, gammas, distance traveled etc. The author has also put together an impressive bibliography section.

Although somewhat dated, this was one of the best books on Interstellar Travel I've read and thoroughly enjoyed reading it. I was impressed by the level of detail and information given by the author and highly recommend the book to anyone.]