Wikipedia:Reference desk/Archives/Science/2008 May 8

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May 8

Taste vs. Smell

I read our articles on "the 5 senses."

When i get sick, I can't really taste anything. Does this mean that taste is a sub-set of the sense of smell? Are the two linked in some way? If I smell something foul, am I also tasting particles of it?

Can those without a sense of smell still taste, what about the inverse?

Thanks-- —Preceding unsigned comment added by 24.218.24.148 (talk) 00:22, 8 May 2008 (UTC)

Apparently if you eat an orange with a banana under your nose, the orange tastes like a banana. Don't know where I read that, sorry. LHMike (talk) 00:28, 8 May 2008 (UTC)

There is definitely a strong relationship between taste and smell. Just try eating something while holding your nose. I don't know the details, though, really... They are the same basic thing, though - both involve detecting certain molecules, either in the air or in things we eat and drink. --Tango (talk) 00:30, 8 May 2008 (UTC)

The taste+smell thing is called flavor. See the article for loads of info. — Kieff | Talk 01:43, 8 May 2008 (UTC)

You may be interested in a recent profile of noted chef Grant Achatz, who has partially lost his sense of taste due to cancer. The article discusses the relationship of scent and taste in some detail. -- Coneslayer (talk) 17:56, 8 May 2008 (UTC)

Smell and taste are both chemical detection methods. While smell primarily works on gases, taste primarily works on liquids. There's lot of overlap though, as many liquids also evaporate to produce fragrant gases, and strong odors also contain gases that can dissolve in the saliva on the tongue. StuRat (talk) 02:03, 9 May 2008 (UTC)

The smell of any substance is recognized by the Olfactory lobe of the brain. The tiny particles from the smelling substance reach the sensors and trigger some particular chemical reactions. On the other hand taste is perceived by taste buds on the tongue surface. But, generally, we recognize any food items by the combined signals of its smell and taste, and memorise the feeling as taste of the substance. It is like matching any object by the use of two different attributes together (e.g. if something is liquide and white in colour, we think it may be milk). However, when one falls ill (specifically cold and caugh), the smell of the food cannot reach the sensors and hence, the individual fails to get the combined sugnal, what he or she recognises as taste of the materials and it appears tasteless to him/her. Also, sometimes medication with antibiotic drugs affects taste buds and everything appears to have a metallic taste. Dr.Rajarshi (talk) 10:33, 9 May 2008 (UTC)

Practically speaking, "smell" only samples gases and "taste" liquids because we happen to sniff with our noses and drink with out mouths. There are few bio-molecular reasons that non-volatile liquids cannot stimulate our smell receptors and volatiles our taste receptors. Indeed, in many species animals will sniff up liquid droplets and thereby smell liquids directly, some even have a distinct olfactory sub-organ for doings so.

As others say, you can both taste without smelling and smell without tasting. Losing one does not alter the detection of the other type of chemosensation. But if you lose one, then you lose the ability to determine flavor, which is the perception we assign to the combined sensation of taste + smell. Flavor is what what we really mean when we talk about the "taste" of something in general terms. This is why it appears we lose taste when we can't smell, because our sense of smell contributes a lot more to the flavour that we generally think. In contrast, losing the ability to taste doesn't have too much effect on smell, because we often smell things without tasting them, but rarely taste things without smelling them.

Incidentally the olfactory bulb (or lobe) doesn't recognize smells per se. The odors are detected by the olfactory epithelium, processed by the olfactory bulb and projected to cortical brain regions, which does the recognition and attribution. Rockpocket 01:38, 10 May 2008 (UTC)

Just try eating bittermelon without tasting at least some of its bitterness. Except in seniors the bitter taste is like 1000x stronger than the sweet taste sensors or something like that. Thanks. ~AH1^(TCU) 01:57, 10 May 2008 (UTC)

Decibels

I read about a set of billboards that show the noise level in decibels of the surrounding area. From an acoustics class I took, I remembered there were a few ways to measure sound levels in decibels. After reviewing the relevant articles in Wikipedia, I deduced the decibel numbers on the billboards are likely sound pressure levels, maybe unweighted or using A-weighting.

When measuring street noise, how large of a difference would there be between the different weightings?

Also in terms of street noise, how much does the location of the sensor affect the decibel reading?

--Bavi H (talk) 00:45, 8 May 2008 (UTC)

dB (decibel) is a ratio, not an absolute measure of sound. Thus, it is valid to say that "ambient sound increased by 20dB" (i.e, there is 100 times more acoustic power) without specifying any particular absolute level. To specify an abolute level, you must relate the level to a particular absolute standard: 0dB(SPL) is the smallest (absolute) acoustical energy perceptible to a (statistically average) human, and 20dB(SPL) is 100 times as much acoustical energy. The various alternative measures differ in the ways they assign weights to the frequencies in the acoustic spectrum. Each such weighting is a convention that derives from some perspective, not a mathematical or physical fact. The only objective measure of sound at a particular location would be a spectral graph, and even that is only valid for a particular integration period.-Arch dude (talk) 01:35, 8 May 2008 (UTC)

To answer your question on the different readings you would get with different weightings for street noise - you cannot say because it depends on the exact frequency content of the noise in that particular street at that particular time. Even with unweighted measurements, it makes a difference what frequency range the measurement is filtered to, but again, this cannot be enumerated without reference to the spectrum of the particualr sound you are measuring. SpinningSpark 21:29, 8 May 2008 (UTC)

Expanding Universe

Thanks everyone for the help so far! But there's still something I'm missing: if the universe is expanding, what is in the space before the universe expands into it? Is it impossible to know how far that area on non-universe goes or if there's something on the other side? Evaunit♥666♥ 00:52, 8 May 2008 (UTC)

Generally, the Metric expansion of space is defined by the objects in the universe, and the distance between objects. Said simply, the expanding universe isn't expanding into anything, it is simply increasing the distance between objects. -- JSBillings 00:58, 8 May 2008 (UTC)

Take a non-inflated balloon. Draw some dots on it. Now blow it up and watch the dots - they move apart as the balloon expands. There isn't an edge of the balloon (considered as just a 2D surface) that's expanding into anything, the expansion is caused by the balloon itself stretching at every point. The universe is the same, just with one more dimension. The only problem with the analogy is that the balloon is a 2D surface existing inside our 3D world - the universe doesn't exist within anything, it simply is, so you need to ignore all of the world except the balloon. Consider what an ant living on the balloon would see. --Tango (talk) 02:04, 8 May 2008 (UTC)

Here's a very concrete thought experiment you can use to understand this concept: Send an astronaut somewhere into space with a stopwatch and a flashlight, and put a mirror very far away from him/her, such that the astronaut and the mirror are stationary with respect to each other. Have the astronaut shine the flashlight at the mirror, and time how long it takes for the light to make the round trip. When cosmologists say "space is expanding", it means that if the astronaut repeats the experiment over time, the astronaut will measure that the round trip time is increasing!! There are a few tricky issues about making the mirror and astronaut "stationary", but they aren't too difficult to figure out. That's basically all we know about this concept of "expanding space". It's anyone's guess what it really means - physicists have come up with an intuitive description of the concept, and a comprehensive mathematical formulism (see general relativity) that seems to describe it. -Bmk (talk) 02:23, 8 May 2008 (UTC)

PS: They have to be very far apart wait a very long time in between trials for a measurable effect (i.e. not on humanly accessible distances or time scales). --Bmk (talk) 04:48, 8 May 2008 (UTC)

Mu (negative) --Shaggorama (talk) 10:17, 8 May 2008 (UTC)

Centrifuge

Seeing as we are now in the era of unmanned space travel for a while, why would it not be a good idea to build a centrifuge in orbit around the earth and use it to catapult unmanned space ships at extreme velocity, thus shortening the time for travel to other planets? Also, as we will be re-entering the 'manned space race to unearthly bodies' in the near future, what effect would this system have on astronauts, considering they are already in practically zero gravity? Would the 9Gs or more affect them? My question is, in a zero gravity environment, how would this work, if at all?--ChokinBako (talk) 03:30, 8 May 2008 (UTC)

A centrifuge, flinging a ship with that much velocity, would itself be flung back towards to Earth with tremendous speed, would it not? I can't envision how this will work... 206.126.163.20 (talk) 03:37, 8 May 2008 (UTC)

Well, you could fling two similar ships in opposite directions without altering the centrifuge station's trajectory much, but I don't really see how this system could become more feasible than rockets. Perhaps it could be valuable for unmanned missions, but according to our article on g-force, NASA recommends limiting human acceleration to around 10 Gs for a few minutes of exposure. A centrifuge that is - let's be very generous - 500 m in radius (that's a kilometer in diameter!) with a centripetal acceleration at the edge of 10 Gs would only send a spaceship flying off at 220 m/s (that's 500 mph), which is not terribly impressive considering unmanned spacecraft going to mars average speeds in the 30,000 m/s (75,000 mph) range. Unfortunately, the speed goes up with the square root of radius and square root of acceleration, so if you double the permissible acceleration and double the radius (which seems improbable to me), you only get 1000 mph exit velocity. I think moon-based linear accelerators (using a rail gun or something) for unmanned craft is more feasible. --Bmk (talk) 04:38, 8 May 2008 (UTC)

Additionally, how are you putting the spacecraft on the centrifuge to begin with? It seems that your options are to either stop and restart the centrifuge or accelerate the craft up to centrifuge speed, neither of which suggests an advantage over just launching the craft normally. — Lomn 12:15, 8 May 2008 (UTC)

You could load them in at the center, then feed them down the length of the arm from there. Also the 2 arms don't have to be the same length, one side could be shorter but more massive, but you still wouldn't even be able to get velocities out of it that would even be close to the orbital velocity of the centrifuge, and if Bmk's correct it would still be going less than escape velocity. Mad031683 (talk) 15:14, 8 May 2008 (UTC)

It might be easier to use a Gravitational slingshot, though I couldn't say for certain as I don't have much expertise in this area. AlmostReadytoFly (talk) 13:18, 8 May 2008 (UTC)

You'd need a booster to get into a trajectory around another planet or you couldn't get the angles right from what I gather, so no savings. This is from an old Discover Magazine article [1] "Meanwhile, mechanical engineer Stephen Canfield of Tennessee Technological University in Cooksville and others are investigating using a whiplike tether to hurl a probe from Earth orbit toward another planet, eliminating the need for a booster rocket. "The idea is to store up a lot of energy by spinning the tether. Then you release that energy by briefly capturing a payload on the tether's end," Canfield says. They also had another rotating system they proposed that tossed and caught loads until it reached escape velocity the concept drawing for it looked sort of like a ninja shuriken with only 2 prongs. (Can't find that one. I had filed it somewhere for later reading.) I admit I'm quite nebulous on the concept, too, but it must work out somehow. The only tether I know of that they tried in earth orbit fried because they hadn't thought they'd get that much juice from just dangling a wire and there was a problem with isolation. Can't figure out how they'd make use of the induction in the spinning tether but maybe the two are not related. You'd get less power in a lunar orbit, but you wouldn't have to deal with an atmosphere. 71.236.23.111 (talk) 21:56, 8 May 2008 (UTC)

An interesting feature of a space elevator is that, if you had one, you could also use it as a centrifugal launch platform: it has to extend some distance beyond geostationary orbit anyway, in order to provide a counterweight to the lower portion, so anything thrown off the top will get flung away from the Earth — the energy for this ultimately coming from the Earth's rotation. —Ilmari Karonen (talk) 12:44, 11 May 2008 (UTC)

Indeed, in one beanstalk proposal I've seen, the height was said to be enough to fling to Saturn or Venus. —Tamfang (talk) 00:35, 14 May 2008 (UTC)

Pls, helping to answer this question !?

What is the difference between macronutrients and micronutrients? Will the consequences of depriving a plant of a micronutrient be less severe than those of depriving the plant of a macronutrient? —Preceding unsigned comment added by 121.1.58.38 (talk) 03:51, 8 May 2008 (UTC)

I would recommend you read wikipedia's article on micronutrients. A macronutrient is simply a nutrient which is required in large quantities to sustain life, like water, carbon dioxide, and nitrates for plants. It's hard to answer your second question precisely - can you be more specific? I would suspect removing water or air supply will kill a plant much more quickly than removal of the supply of most micronutrients. --Bmk (talk) 04:22, 8 May 2008 (UTC)

First of all I would like to differ and negate the answer given above. It was wrongly dealt with. However, to answer your question, both micro and macro nutrients can be defined as essetial elements required for the plant growth and defficiency of which leads to certain metabolic disorders having definite symptoms. Only difference is that micronutrients are necessary in micro quantity while macro nutrients are necessary in large quantity for the plants growth. Carbon, Oxygen, Nitrogen, Hydrogen, Calcium, Magnaseum, Phosphorus, Potassium and Sulfur are macro nutrients, while Iron, Chlorine or Chloride, Zinc, Molybdenum, Manganese, Copper, Boron are major micronutrients. Sometimes Iron is also kept in the list of macro nutrients. So, difficiency of any of any of the nutrients will be similarly sever, and that will have some definite symptoms. —Preceding unsigned comment added by Dr.Rajarshi (talk • contribs) 05:14, 8 May 2008 (UTC)

I might be missing something here but the good doctor Rajararshi vehemently seeks to "differ and negate" from Bmk's reply, but then paraphrases it almost word for word. Bmk is wrong (I believe) to class air and water as nutrients, but apart from that their answers are much of a muchness Myles325a (talk) 03:09, 9 May 2008 (UTC)

Both answers agree on the definition of macro and micro nutrients. After that point, I think Bmk and Dr.Rajarshi are talking about 2 different things. I think they are both right.

Bmk talks about whether lack of a micronutrient will kill a plant. I think a plant with an adequate supply of micronutrients could live a long time if its supply of micronutrients was stopped (i.e, it did not get any more, but kept what it had.)

Dr.Rajarshi says that a deficiency in any nutrient, macro or micro, will cause definite symptoms. If a plant needs a particular nutrient to grow normally, lack of that nutrient will stop it from growing, or at least affect its growth.

That's my take on it. CBHA (talk) 04:47, 9 May 2008 (UTC)

The comment has flickered some controversies, which may not be desirable. But, the terms 'macronutrient' and 'micronutrient' are two definite scientific terminologies and those refer only to the nutrients listed above. There is no scopes left, that both the answers are correct. However, it is absolutely right that, if any of the nutrients (be it micro or macro) is necessary for growth, then deficiency of the same will affect the growth. It is also true that if the minimum amount of nutrient is available, then the proper growth and other functioning will continue, irrespective of the fact, whether it is being supplied from outside or not. Dr.Rajarshi (talk) 09:57, 9 May 2008 (UTC)

Organic Matter

Organic matter is not advisable to be added to paddy soils. Yes or No? Why? —Preceding unsigned comment added by 121.1.58.38 (talk) 03:59, 8 May 2008 (UTC)

Decomposition#Plant decomposition, Eutrophication and Hypoxia (environmental) might help. --71.236.23.111 (talk) 06:17, 8 May 2008 (UTC)

Pic

At 2:05 in [2], there's a picture of a cat with crazy blue eyes. Is that really possible? Black Carrot (talk) 05:23, 8 May 2008 (UTC)

No, it is photoshopped, to make the kitten look like someone who takes spice. --98.217.8.46 (talk) 20:22, 8 May 2008 (UTC)

Gingiva Recession

My gums are receding. My dentist says it's probably genetic. But I did not tell my dentist that my sister and mom have recession (see below).

My sister has recession, and I believe she has been flossing once and brushing twice a day. I never had recession, and my dental hygenine is the same. I think I am actually noticing recession. Is that possible? Because I haven't changed how I brush and floss to months ago, but it seems like my gums are receding faster. Also, my mom has recession, but she doesn't floss every day, but I think she at least brushes once a day.

Why can't recession be reversed, as in, why can't I build up bone growth again? How come I lose bone growth and can't gain it back? What are the causes of genetic gum recession? And have there been research to determine if bone can be rebuilt (in terms of gum recssion)? If not, why can't bone be rebuilt (in terms of gum recssion)? And what new research is being done to see if bone can be rebuilt? What are the new techniques? Thanks so much for all your help.68.148.164.166 (talk) 02:45, 7 May 2008 (UTC)68.148.164.166 (talk) 02:48, 7 May 2008 (UTC)68.148.164.166 (talk) 02:48, 7 May 2008 (UTC)

This is not medical advice and I'm no expert, but you might find more information on the following pages Receding gums, Periodontitis (look at the mention of risk factors there), Osteoimmunology As to your question why it can't be reversed (yet?) may be that despite surprising results (see Refdesk, "Humpty" May 2 ) our understanding of how cells work and what it takes to start and stop them from growing is still poorly understood. Particularly in dentistry, bone grafting and autologous (own) Stem cell treatments are areas with lots of studies on the way. Whether the results will be generally applicable, feasible and when they will reach common practice is another question. Lisa4edit (talk) 04:05, 7 May 2008 (UTC)

(see Refdesk, "Humpty" May 2 )???68.148.164.166 (talk) 09:40, 8 May 2008 (UTC)

Look particularly at the Scientific American article linked [3] I hope this works. If not click "Archive" above and look at May 2 in the Science desk archive. 71.236.23.111 (talk) 19:51, 8 May 2008 (UTC)

subliminal masseging

how to make subliminal messaging to subconcious mind —Preceding unsigned comment added by 117.197.48.133 (talk) 17:09, 8 May 2008 (UTC)

Subliminal message? Not sure what you're asking. --Ouzo (talk) 17:45, 8 May 2008 (UTC)

As a note, subliminal massaging would be, well, not that much fun, I imagine. Or would it? --98.217.8.46 (talk) 18:03, 8 May 2008 (UTC)

Really? Then why do you feel so good today? Nil Einne (talk) 19:34, 8 May 2008 (UTC)
Let's just get that nice spot right between your shoulder blades. Isn't that nice? Just relax, and let my hands take care of the work.

Huh? I don't know what you are talking about. There's no such thing. Obvious nonsense, that's it. --98.217.8.46 (talk) 20:24, 8 May 2008 (UTC)

It was once 'obvious nonsense' to propose the Earth was round. Don't dismiss things, unless you have proof to the contrary. Regards, CycloneNimrod^Talk? 20:29, 8 May 2008 (UTC)

I think you missed the joke. --98.217.8.46 (talk) 02:48, 9 May 2008 (UTC)

Please then, share your subliminal massaging technique. 24.76.169.85 (talk) 20:52, 8 May 2008 (UTC)

Sorry to post spam, but actually, you can buy such a thing [4] SpinningSpark 20:56, 8 May 2008 (UTC)

Havat our article on Hypnosis. Julia Rossi (talk) 23:54, 8 May 2008 (UTC)

If you are refering to "Neurolynguistic Programing" techniques, I can help you. An example of one of these tactics would be as follows:

Say you need to feel more confident. Close your eyes, and visualize yourself in a past time, when everything just clicked (everyone has at least one, whether it was with family or close friends.) Visualise yourself in the moment, pay close attention to the sounds, visuals, and environment. Try to make them as vivid as possible. Now imagine yourself stepping out of the "flashback" and see yourself watching yourself in this situation. This allows you to become an observer. Take some time, once again to visualise and make sounds, pictures, and envioronments as real as possible. Following this, (still playing an observer) imagine a time when you'll need this confidence again, say like a party, or a wedding. From there, visualise yourself stepping into that scene (whatever it may be). Once again, try to make everything as real in your mind as possible. Open your eyes, and let your subconcious do the rest!. This technique can be applied wherever needed. Even if you are nervous for a test. I use these techniques all the time, they work wonders for me. However, everyone's different. I would be interested to know who this helps, though. Please give feedback. —Preceding unsigned comment added by 72.40.54.255 (talk) 15:09, 12 May 2008 (UTC)

Validity of Sigmund Freud's work

From a scientific standpoint, how accurate or valid are Freud's theories? In particular, he introduced the world to the concepts of id, ego and super-ego, the unconscious, and others. Are these measurable? If so, how? If, not, why do they still hold such prominence in western society? —Preceding unsigned comment added by 72.35.21.126 (talk) 20:42, 8 May 2008 (UTC)

Psychology is a social science for a good reason, it studies empirically how people act but it, usually, doesn't relate all that much to biological function. Yes, we can detect things like depression by changes in chemicals and the like, but things like the ego are unmeasurable beyond visual observation and just listening. Regards, CycloneNimrod^Talk? 20:56, 8 May 2008 (UTC)

There's a lot of current discussion about this, actually. There are some who argue that modern neuroscience has vindicated some aspects of Freud's work and some who are that it has disproved it. There are also those—largely psychoanalysts, I believe—who argue that Freud's description was not meant to be a literal biological description of the mind, but is a set of concepts that maps well onto how the mind functions, and thus serve as tools for affecting what, at some level, has to be the the neurological basis of behavior and emotion (analogous argument: the basic principles of engineering can be used without any knowledge of how they correspond with quantum mechanics; a reductionist approach can be unreliable on larger scales). And there are those who argue that it is a 19th century, overly literary approach to what should be a harder science. From what I can tell it is all over the board at the moment.

The question of prominence in Western society is a difference one, though, from the question of whether modern neuroscientists use Freud. Freud is wonderfully literary and his idea of deep seated drives, secrets, and internal struggle is one that has appealed to Americans in particular since the 1940s. The ideas triggered strong cultural valences in postwar America and still holds sway today, even though most people know jack squat about cognitive behavior and science. --98.217.8.46 (talk) 23:04, 8 May 2008 (UTC)

Dont forget the idea of psychological energy. The idea that mental processes are subject to 'forces' and 'energies' just like physical processes are. http://en.wikipedia.org/wiki/Psychic_energy. Em3ryguy (talk) 23:25, 8 May 2008 (UTC)

By the way, this article is a combination of 2 articles. 'psychological energy' which is scientific and 'phychic energy' which isnt. see the discussion page for comments. Em3ryguy (talk) 00:15, 9 May 2008 (UTC)

That entire article reads as though it's riddled with pseudoscience. It's especially hard to tell as it isn't well sourced. 206.126.163.20 (talk) 00:23, 9 May 2008 (UTC)

The whole point of psychological energy was to show that mental phenomena are subject to laws just like physical ones. Someone who didnt know what they were doing combined that article with the 'psychic energy' article and screwed it up. Em3ryguy (talk) 00:50, 9 May 2008 (UTC)

The original version of that article describes Freud's theory of energy as 'psychic energy' and directs the reader to that pseudoscience article. I dont believe that is accurate. Em3ryguy (talk) 01:04, 9 May 2008 (UTC)

The original version of the article was poorly explained itself. I'm reading it right now and I don't get the point. It says "Some people think everything in the mind can be explained in terms of energy, though mainstream scientists are hesitant to accept this... general things about hormones and neurotransmitters follow". The last part of which could be stripped out, leaving the article with only a single sentence. That's like an uber-stub. 206.126.163.20 (talk) 01:52, 9 May 2008 (UTC)

Stereographic projection

Stereographic projection example

I need help to make sure that what I wrote at Template:POTD/2008-05-13 actually makes sense. Asked at Talk:Stereographic projection with no response, so trying here. Yes, I know that the article talks about representing spheres with 2-D pictures, and this is kind of the opposite, but it's way down at Stereographic projection#Photography. I mostly just copied-and-pasted from there, but since I didn't really understand this section of the article, I'd like more eyes please. Thanks. howcheng {chat} 21:15, 8 May 2008 (UTC)

You're close. I think the point opposite actually becomes infinitely enlarged - since the picture has only finite area, it isn't the whole sphere, it's the sphere with a small disc around the opposite point removed (roughly - the picture isn't circular, so it won't be quite a disc). --Tango (talk) 22:20, 8 May 2008 (UTC)

Nuclear Bomb Powered Rocket Project

I'm intrigued by a project from the 1950s or 1960s for building a spaceship which was powered by a number of nuclear bombs inside itself, going off at regular intervals to propel the vehicle. I wonder why this was even considered, as if one bomb went off, it would set all the others off, probably devastating half the planet in the process. Sure, it would get into space (or bits of it), but it wouldn't be a good way to do it. The fix for this would be to put each bomb inside some sort of material that is resistant to a nuclear blast, but this would just make the bombs go off inside their own casings and nothing would happen. It seems that NASA actually funded this project, and I have heard a rumour (sorry, forgot source) that they are even considering it again now. Is this true and is it even feasible?--ChokinBako (talk) 23:07, 8 May 2008 (UTC)

Project Orion (nuclear propulsion). First, you don't start the nuclear explosions on Earth, so there's no way for Earth to be "devestated." It would certainly take some radiation from orbital detonations, but if I recall correctly, such an explosion would only have enough radiation to kill ten people (proabalistically speaking, from the increased likelihood of cancer). Once the ship is out of orbit, that would cease to be an issue. As for the explosions destroying the rest of the nukes, this is sovled very easily in the two ways you could do this. If you're firing nukes at the ship from Earth or from an orbital/moon based/whatever platform, then you simply have the explosions take place far enough apart that each nuke is always outside the destructive radius of the previous nuke's blast. If the ship is carrying its own nukes, it simply waits until after each explosion to drop the next one in place. Someguy1221 (talk) 23:45, 8 May 2008 (UTC)

Ah, I see. So, the idea was that the ship would actually 'let go' of one bomb at a time and let them detonate a safe distance from the ship, but close enough to get the propulsion? The diagrams I have seen in the past just showed a rocket with about ten or twenty nuclear bombs inside it and didn't explain that bit. It seems to make some sense now. Thanks.ChokinBako (talk) 00:54, 9 May 2008 (UTC)

That's exactly right. The ship shoots the bombs out behind it, then the bomb detonates, and the force of the explosion is picked up by a big plastic plate (the pusher plate) when then imparts the radiant energy as kinetic energy, moving the ship. This YouTube video does a pretty good job of illustrating its pulsing approach right after it gets out of the atmosphere (in the "re-imagining" of the concept by the guy who made the video, he has it taking off with chemical rockets, to avoid fallout problems on Earth). --98.217.8.46 (talk) 02:39, 9 May 2008 (UTC)

The plan was indeed for the nukes to go off on Earth, as the spaceship was to be far too heavy for a chemical rocket to get it into space. The planners even specified that it would have one of those enormously heavy swiveling barber's chair, just to thumb their noses at the extremely-weight-restricted chemical rocket crowd who eventually won the day at NASA. The effects of atmospheric nuclear explosions were only just becoming known at that time, and when their danger became clear the project was doomed. One of my favorite books is The Starship and the Canoe, a dual biography of Freeman Dyson, who was one of the principal Orion people, and his son George Dyson, who lived in a tree in British Columbia. --Sean 01:03, 9 May 2008 (UTC)

Oh, I didn't realize that was actually the case. In any event, you could still use the concept as an in-space-only propulsion mechanism, since you can still send up your 400 ton space ship in little pieces, then use the bombs for the heavy work of getting to Alpha Centauri in a meaningful time frame. Someguy1221 (talk) 01:37, 9 May 2008 (UTC)

Here's a nice government-produced picture of where the bomb would go off relative to the spaceship, and then it would explode, and then push up against the "pusher plate" of the spacecraft, which would be made of a material that would reflect the energy primarily. Following Newton's whatever law, the act of this reflection would exert an equal and opposite force on the spaceship itself, pushing it along. --98.217.8.46 (talk) 02:45, 9 May 2008 (UTC)

Larry Niven and Jerry Pournelle used this propulsion method in their science fiction novel Footfall. They make the interesting point that for a launch from earth it is the second bomb that is crucial. If the first one fails - well you are still sitting on the deck, have another try. If the third one fails while you are in the air, you have enough time to detonate another. However, if the second one fails, thousands of tons of concrete platform (or whatever you have made the vehicle from) come crashing back to the ground before any corrective action can be taken. SpinningSpark 17:07, 9 May 2008 (UTC)

The fallout issue is unfortunate, because an Orion engine is twice as efficient in an atmosphere as it is in space: the atmosphere lets you catch more of each bomb's energy. --Carnildo (talk) 21:30, 9 May 2008 (UTC)