Wikipedia:Reference desk/Archives/Science/2011 March 31

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March 31

Space and matter shortly after the Big Bang

Hi

1. In the early Universe, just after the Big Bang, was there "as much space" as there is now but compressed into a smaller volume, or was there actually "less space"? If there was "as much space" then in what sense was the Universe "smaller"?

2. In the time shortly after the Big Bang, were particles and atoms in some sense actually "smaller" than they are now? Or did the formation of matter have to wait until enough space had been created to contain it?

86.177.108.189 (talk) 00:19, 31 March 2011 (UTC)

1. What's the difference?
2. There were no atoms. Only a subatomic particle soup. Dauto (talk) 00:33, 31 March 2011 (UTC)

If there was "as much space" then "as much stuff" could fit into it (e.g. all the atoms that now exist), yet that stuff would be "smaller" in some sense that I do not understand. If there was "less space" then "less stuff" could fit into it. In the latter case, as we get smaller and smaller, eventually there would be no room for the particles in your soup. Then what? Just energy in some other form? 86.177.108.189 (talk) 00:53, 31 March 2011 (UTC)

(edit conflict) I think I see what you are getting at. There was actually less space; in the sense that the stuff that was not space (matter and energy) was all closer together. The big bang and inflation created the space in which matter and energy organized itself into its current state. See Metric expansion of space and Timeline of the Big Bang and Inflationary epoch and Inflation (cosmology). Your sense is correct; all the "stuff" in the universe was compressed so there was a lot less room, even down to a singularity at the moment of genesis. --Jayron32 03:49, 31 March 2011 (UTC)

In simple terms, yes. The universe was much, much smaller, and all of the mass-energy was compressed into that very small space. I say mass-energy because at that density it's practically impossible for particles as we know them to exist, and it was all pretty much just high-energy photons. After a while, as the universe expanded, the energy density dropped, and particles started to condense out - starting with the really small ones like quarks and leptons. Check out Timeline of the Big Bang for more info. Confusing Manifestation(Say hi!) 03:45, 31 March 2011 (UTC)

Atoms were never smaller. But atoms only exist at low temperatures, because it doesn't take much energy to knock the electrons off, and it doesn't take much more than that to knock the nuclei apart. So physics is effectively different at higher temperatures, though the laws are the same. At even higher temperatures, the Higgs field gets knocked out of its nonzero vacuum state, and concepts like "electron" and "photon" break down, though the laws of physics are still the same. At even higher temperatures, nobody has any idea what happens (but I suppose the laws of physics are the same even then, by definition...)

Generally, things can be smaller at higher temperatures because there are more accessible fermion states. Ordinary matter is hard to compress because all of the low-energy electron states are occupied, and you aren't strong enough to push a substantial fraction of the electrons into higher energy states. But far more compact configurations of matter are physically possible when the energy is available.

I don't agree with ConMan's response. At high enough temperatures you can pair-produce arbitrary Standard Model particles, so all of the particle types are equally represented in the soup. (And, as I said, at even higher energies the low-energy particle types are meaningless.) I'm also unhappy with the idea that small things condense out first. Things condense out when there's insufficient energy to knock them apart.

I think the "Timeline of the Big Bang" article is of rather poor quality right now. The "inflationary epoch" is certainly misplaced; it should have no start time, since (1) A.B.B. times only make sense post-inflation, and (2) nobody has the slightest idea how long inflation lasted, nor what the pre-inflationary state might have been. I don't want to rewrite the article, though, because I don't really know very much about high energy physics. -- BenRG (talk) 05:56, 31 March 2011 (UTC)

• Thanks for the replies. I'm still a little confused about how we actually measure the size of things when space is not constant. In principle, could we take a 30cm ruler back to the time when the Universe was 30cm across and find that the ruler only just fitted (ignoring practical complications such as the conditions being too extreme for the ruler to survive)? Let's assume the answer is "yes". Then, over billions of years, space has expanded, but the ruler has stayed the same size? How does that work? Space must be expanding in all places, right, so why isn't it expanding "inside" the ruler, thereby stretching it? (Imagine the ruler is a drawing on the surface of a balloon. As the balloon inflates -- as space expands -- the ruler gets bigger.) This is what I don't understand. Thank you! 86.179.115.14 (talk) 12:58, 31 March 2011 (UTC)

I will say "yes" to your first question, although most solids vary in size with temperature and no solid can exist at those temperatures. A better answer is that the laws of the Standard Model haven't changed (it's thought) and various length scales can be derived from that. For example, the confinement scale of the strong force is about a femtometer, and that was the same back then. This is how the size of space is defined, essentially—it's the amount of space you'd need now to reproduce similar conditions in the lab. If the physical laws were different, there would be some fuzziness in how much the universe had expanded.

The reason rulers don't lengthen as the universe expands is the same as the reason they don't lengthen in other circumstances. Rulers are bound together by forces that, for complicated reasons, prefer a certain separation between particles and resist attempts to increase or decrease the separation. The laws of physics don't change, so the preferred separation doesn't change. There's nothing special about the recessional motion associated with the expansion of the universe; it is the same as any other recessional motion as far as the laws of physics are concerned.

Self-gravitation does act on rulers; it's constantly squeezing them. They don't collapse into black holes because the forces binding the ruler resist compression with a force that roughly follows Hooke's law (everything is like a spring under small enough deformations). Self-gravitation compresses the ruler until the opposing force matches the compression force, and the ruler remains permanently in that equilibrium state. It's slightly smaller than it would be without gravity, but it doesn't get smaller over time. If the cosmological constant is real then it also acts on rulers, trying to pull them apart, but because rulers resist pulling also, the effect is again just a slight change in the equilibrium size (much smaller than the effect of self-gravitation, which is already very small). If there were a pushing/pulling force directly associated with the expansion of the universe (which, I want to stress, there is not—Aristotle was wrong about that), it also would simply change the equilibrium size. -- BenRG (talk) 18:38, 31 March 2011 (UTC)

Ben, thank you for your very helpful answer. If I could prevail upon you again: At the time when the 30cm ruler only just fitted into the Universe, did it only just fit because it hit a boundary, or "edge", of available space? I'm guessing the answer to this is "no", but if there is no boundary or edge stopping the ruler extending further, then what would prevent us placing a longer ruler in the same Universe, thereby contradicting the proposition that the 30cm ruler only just fitted? 86.179.117.213 (talk) 01:04, 1 April 2011 (UTC)

When you hear figures like 30cm being quoted, those are the size of the visible universe at that time. In other words, the matter making up the present-day visible universe fit in a 30cm sphere (I'll take that to be the diameter, but a factor of 2 hardly matters). The universe presumably continues past that point, although we can't see it because the light hasn't reached us yet. We have no idea how large the entire universe is, nor what the nature of the boundary would be, if there is one.

But that doesn't mean your long-ruler question is uninteresting. It's actually quite subtle, and made me realize something I hadn't thought about before, which is that a quasi-rigid ruler that spanned the visible universe back then would actually be larger than 30cm now. The reason is that if all points on the ruler are at relative rest, then back then both ends of the ruler were moving rapidly inwards with respect to the Hubble flow, and therefore were Lorentz contracted with respect to cosmological coordinates (which take the Hubble flow as the local standard of rest). So if the coordinate length of the ruler then was 30cm, its proper length (which we would measure now) would have to be larger. Also, you run into difficulties with what it even means for a large solid object to exist at that time, because of synchronization issues. The time since the big bang is the same for all particles moving with the Hubble flow, but it would be different for different parts of the ruler.

So it's really necessary to measure the diameter with smaller rulers. 30 rulers of a centimeter each, maybe, which are moving with the Hubble flow. At the moment in question they all line up end-to-end and span the visible universe; a moment earlier they overlap and a moment later there are gaps between them. If you could gather them up today and arrange them end to end, they would total 30cm. -- BenRG (talk) 04:44, 1 April 2011 (UTC)

Thank you very much, that's very helpful. 86.179.115.50 (talk) 13:18, 1 April 2011 (UTC)

Shrinking Sun

According to the article Formation and evolution of the Solar System and Future of the Earth, the Sun is getting warmer and brighter by around 10% every 1 billion years because of the helium build-up at its core (nearly half the hydrogen has been consumed). This will wipe out Earth's life even before the time of the Red Giant. Now what the young-earth creationist use as evidence for their young Earth is the proof that the Sun is shrinking at 5 feet/hour. Try googling shrinking Sun. Is it really true? The two statements above seem contradictory. Please tell me which one is right. Aquitania (talk) 00:35, 31 March 2011 (UTC)

The evidence that the sun is shrinking is not very good, but I think the idea is that the sun is contacting, and therefore getting warmer in its core (since the extra density causes fusion to happen faster). Although like you I would have expected a warmer sun means a bigger sun, I think that's impossible: A bigger core (of the same mass) means lower energy production, so the core can't be any bigger than it is now. (In a red giant the core is small, but the outer layers are large.) Ariel. (talk) 01:11, 31 March 2011 (UTC)

Each Helium nuclei has half the electric charge and a quarter of the particles of the four protons it replaces. Therefore Sol has less volume (and higher density) and very slightly less mass. Hcobb (talk) 01:34, 31 March 2011 (UTC)

"...half the electric charge..." yes, but only because you have ignored the 2 positrons released when each of two proton pairs fuses into a deuterium nucleus - there is no overall loss of charge (obviously). "... a quarter of the particles ..." - I don't follow this at all - there are 4 nucleons both before and after fusion. Gandalf61 (talk) 09:24, 31 March 2011 (UTC)

Gandalf, Hcobb is talking about reducing the number of nuclei which is the number that appears at the ideal gas law PV=nRT, that governs pressure in non-degenerate matter. Dauto (talk) 12:28, 31 March 2011 (UTC)

And does the core of a star behave like an ideal gas ? As it is a plasma, I would have thought its equation of state would be much more complex. Gandalf61 (talk) 13:02, 31 March 2011 (UTC)

Yes, the core of a main sequence star does behave like an ideal gas. $P=\rho R^{*}T\,$ where $R^{*}\,$ is proportional to the number of particles per molecular weight $R^{*}\sim (2X+0.75Y+0.5Z)\,$. The quantities $X\,$, $Y\,$, and $Z\,$ are the hydrogen, helium, and metalicity mass fraction respectively. So hydrogen contributes two particles (a proton and an electron) per nuclei (which has a molecular mass equal to one): $2/1=2\,$, helium contributes three particles (a nucleus and two electrons) per nuclei (which has a molecular mass equal to 4): $3/4=0.75\,$, and metals contribute (n+1) particles (a nucleus and n electrons) per nuclei (which has a molecular mass equal to 2n): $(n+1)/2n\approx 0.5\,$. Dauto (talk) 15:17, 31 March 2011 (UTC)

When was the last time young earth creationist were right about anything? Dauto (talk) 03:27, 31 March 2011 (UTC)

The problem with that arguement, is that young earth creationists assume that that trend can be extended indefinitely backwards in time. This kind of error is sadly not uncommon. Plasmic Physics (talk) 07:32, 31 March 2011 (UTC)

It is physics 101 or an entry level astronomy class where you learn about the physics of a star, how stars exist by a balance between their mass and the laws of gasses. Gas particles repel eachother. The gravity of a body holds them back. If the mass of the star decreases, the gas particles are allowed to expand away from eachother. If too much of the gas turns into heavier elements thus no longer being a gas, the star ends up having less gas to fight the star's gravity and the star collapses under it's own weight. —Preceding unsigned comment added by 108.67.181.74 (talk) 04:11, 2 April 2011 (UTC)

Size of the universe

How big is the universe? — Preceding unsigned comment added by JoshuaDonald (talk • contribs) 04:36, 31 March 2011 (UTC)

We don't know. It could be infinitely large, or perhaps has finite limits but which the laws of physics do not allow us to probe. See Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws and Shape of the universe and Observable universe for some extended content on this matter. --Jayron32 04:39, 31 March 2011 (UTC)

There is an interesting concept explaining the big bang and the form of the universe: http://www.teach-nology.com/forum/showthread.php?p=46964 108.67.181.74 (talk) 04:21, 2 April 2011 (UTC)

Would I be able to donate extra skin and fat cells for $?

As I was in Germany as a toddler, I can't donate blood. _{(After over 20 years of not being in Europe, I clearly don't have CJD, but it'll take a lot to get that through the FDA's thick heads.)}

As I'm 11-13 lbs. overweight, and aware of how organs are sold for money, what about donating my extra skin and fat cells to anyone who may need it? Where do I go to get this to happen, and how much $ would I earn per lb.?

Other than that, what CAN I donate (that will replenish/regenerate, so no kidneys, for example) that will still net me some funds? --70.179.169.115 (talk) 11:26, 31 March 2011 (UTC)

I think you're out of luck. Dauto (talk) 12:24, 31 March 2011 (UTC)

Doesn't somebody need skin grafts at any point in time? Also, if fat tissue has been burned, that would need replacement too, right? --70.179.169.115 (talk) 13:18, 31 March 2011 (UTC)

For your second question you might be able to sell blood plasma and gametes (the second is easier for males then females). Googlemeister (talk) 13:15, 31 March 2011 (UTC)

Gametes? Okay then, where is the closest gamete donation center to 66502, please? --70.179.169.115 (talk) 13:18, 31 March 2011 (UTC)

As an aside, I will note that the latent period of CJD infection can run into multiple decades, with some speculation that it may take up to 50 years for symptoms to appear. TenOfAllTrades(talk) 15:13, 31 March 2011 (UTC)

The restrictions on donors with vCJD are borderline paranoia, given that the number of total cases is vanishingly small and the impending epidemic never happened. The restrictions on blood donation are restrictive because people are still paranoid about disease risks, and it leads them to refuse life-saving treatments. Better to deal with their fears ahead of time. I'm not aware of adipose tissue donation. Skin donation is almost entirely either autografts (i.e. from one spot on the patient to another) or from cadavers, and has the same restriction on European residence anyway. Semen/oocyte donation, as of 2005, now has the same restriction unlesss you're giving for someone that knows you and they're notified of the potential risk up front. You can't donate a kidney for money in the US anyway. There's a blood test for vCJD which has been proven on paper, but it'll probably be at least several years before it's commercially available, since getting it to work is one thing, nailing down specificity and sensitivity to a decent level is another entirely. For the record, routine blood donors are not paid (again, volunteers are felt to be safer). Plasma donation is paid in the US, even though the World Health Organization frowns on that practice. SDY (talk) 16:52, 31 March 2011 (UTC)

Out of interest here are the precautions taken in the UK against transmission of CJD in donated blood. A far worse disaster in the UK was the use of blood imported from US prisons in the 1980s. Alansplodge (talk) 18:32, 31 March 2011 (UTC)

We have an article on that topic, though it looks like the UK-specific article is yet to be written. People got scared for a reason. What's sad is that some of this same issue was repeated in China, but there it was shared needles resulting in something like a quarter of a million HIV infections (again, shortcuts for economic reasons). There it was the donors, haven't heard anything about the recipients. Modern processing techniques are fairly thorough, but I wouldn't be surprised if some slipped through. SDY (talk) 19:18, 31 March 2011 (UTC)

Obsolete or speculative physical theories

Are speculative physical theories that don't make any predictions that can easily be tested still considered to be "scientific"? Are obsolete physical theories considered to be unscientific? I ask because in this thread an editor is convinced that Einstein-Cartan theory is some combination of "wildly speculative", "not science", and "pseudoscience". In the end, he says it's mathematics, not physics. To me, that doesn't seem fair to established speculative physical theories (e.g., Brans-Dicke theory, string theory, quantum gravity). But I'm a mathematician, not an empirical scientist. I'd like a broader view on this question. Sławomir Biały (talk) 12:25, 31 March 2011 (UTC)

It is relevant to point out that our definition of hypothesis says "For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it." Even our article on theory says "Such theories are preferably described in such a way that any scientist in the field is in a position to understand, verify, and challenge (or "falsify") it." Keep in mind these are fairly narrow definitions, and alternate formulations end up being more about philosophy of science than about science per se.

The work of applied mathematicians, theoretical physicists and their ilk often falls through the cracks of easy-to-formulate definitions of science. Certainly marking string theory as 'pseudoscience' would be perverse. Though I am not that familiar with this notion of Torsion field physics, some of the views at the talk page constitute extremely hard-line bias towards empiricism as the only valid form of science. Consider this: lack of obvious testable predictions does not mean a proposition or theory is not falsifiable. If a case can be made for falsifiability, then you have a good claim that the theory is scientific under the Popperian scheme of science. SemanticMantis (talk) 15:22, 31 March 2011 (UTC)

Slightly off-topic, but: In general relativity you can think of continuous mass distributions (the stuff that appears in the stress-energy tensor) as a continuum limit of a bunch of tiny nonrotating black holes in vacuum. If they're rotating, the continuum limit has torsion. So it's easy to argue that Einstein–Cartan theory is more natural than general relativity, since it doesn't impose an arbitrary constraint on black holes in the continuum limit. The difference between Einstein–Cartan theory and GR is too small to be tested, but neither theory is to blame for that. If you wanted to discard one theory, it would have to be on the basis of Occam's razor. GR has simpler math, but E–C appears to me to have fewer arbitrary assumptions. Newtonian gravity has simpler math than GR, but GR has fewer arbitrary assumptions. So this argument would seem to favor E–C gravity. I suppose the broader point is that the testability of a theory depends somewhat on what alternatives are available. Every theory makes many predictions that aren't testable (because we don't have any labs on distant planets, for example). That doesn't matter until a rival theory comes along that predicts the same result in a lab on Earth but a different result on another planet. Suddenly the untestability of the distant-planet prediction becomes a problem. It's not fair to blame the new theory for that just because it was invented later. -- BenRG (talk) 23:20, 31 March 2011 (UTC)

Very interesting posts. Thanks! Sławomir Biały (talk) 12:55, 2 April 2011 (UTC)

Many theories have been replaced during modern science, for example the continental drift theory by plate tectonics, the cosmological constant by dark energy and the luminiferous aether/corpuscular theory both by variously concurrent theories of light (Wave–particle duality, neutrino theory of light, photon, Maxwell's equations, quantum optics, quantum electrodynamics, light transport theory, solid light, emission theory, etc). Nowadays, some scientists are looking to complete the Standard Model of physics by creating a Grand Unified Theory and using results from experiments such as at the Large Hadron Collider. ~AH1^(TCU) 23:30, 3 April 2011 (UTC)

Temperature induced nuclear fission

How do I calculate the theoretical ratio of free nucleons to nuclei in a nuclear plasma, as a function of temperature, pressure, and muclear binding energy? Plasmic Physics (talk) 12:56, 31 March 2011 (UTC)

I don't understand your question. could you elaborate? Dauto (talk) 00:49, 1 April 2011 (UTC)

At the temperature increases for a electromagnetic plasma gas, a new type of plasma develops. I say plasma gas, because a plasma is not a distinct phase like a solid or liquid, as a table salt is considered a solid example of a plasma. This plasma is a nuclear plasma gas - in a nuclear plasma gas, nuclear fission of normally stable nuclei is induced. In this process, the binding energy is overcome by the thermal energy. Since temperature is equivalent to the average thermal energy of a bulk sample, not all nuclei would have energies over the threshold required for nulear fission to be induced. In addition to this, there is a continueum of discrete fission products ranging from no fission, to individual nucleons. So, it is fair to say that across a change in temperature, a gradient of proportion should exist for a specific fission product. Plasmic Physics (talk) 01:37, 1 April 2011 (UTC)

Anyone? Plasmic Physics (talk) 23:29, 1 April 2011 (UTC)

If I understand you correctly you want to know how to calculate the concentration of free nucleons given temperature, pressure and assuming thermodynamic equilibrium. That is done the same way that the concentration of chemical species is calculated for a given reaction. You must calculate the Gibbs energy for the system and minimize it. Read Chemical equilibrium You will also find useful the article thermodynamic potential. specially the section Thermodynamic potential#The equations of state. Dauto (talk) 04:35, 2 April 2011 (UTC)

Helpful, how sure are you that it exists in a state of equilibrium? Plasmic Physics (talk) 07:20, 2 April 2011 (UTC)

It's your question. You must have some physical situation in mind. Good judgment must be used to decide whether thermodynamic equilibrium is present or whether a quasi equilibrium is a good approximation. Just note that if there is no equilibrium then your question is ill posed because you would have to know the initial condition (concentration of each relevant species) and then use each reaction rate (based on their cross sections and on the availability of the reactants) to integrate the evolution of the concentration of those species to find their final concentrations. Dauto (talk) 14:37, 3 April 2011 (UTC)

Thank you, I can use this information. Plasmic Physics (talk) 09:13, 4 April 2011 (UTC)

Isn't there an anti-hunger pill anywhere?

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). --TenOfAllTrades(talk) 01:03, 1 April 2011 (UTC)

I had an anti-hunger pill just the other day. It's called the Big Mac. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:36, 2 April 2011 (UTC)

Green Laser

I have one 20mW green laser pointer. It does not burn matches (as I daydreamed) yet gives a slight sensation of heat on skin. It works on 3 AAA batteries (alkaline). My question is that if I add more voltage will it increase in power, say burn paper etc.  Jon Ascton  (talk) 14:10, 31 March 2011 (UTC)

No. Excessive voltage will simply destroy the laser diode. Roger (talk) 17:00, 31 March 2011 (UTC)

You are probably right. But I have heard that using a typical 3.7 volt Li-ion (rechargeable) battery will make it more powerful. What do you say to that...

What is the voltage of the current battery? A higher voltage will increase power output up to the rated maximum a further increase in voltage will destroy it. However it is most probably already operating at, or very close to, its maximum anyway. Roger (talk) 08:25, 1 April 2011 (UTC)

The current voltage, as I have stated above, is 4.5 volts (3 AAA batteries), yet a 3.7 volt is said to make it more powerful.

That is completely illogical - reducing the voltage while leaving everything else unchanged will reduce the power. Power = Voltage x Current. Roger (talk) 12:37, 2 April 2011 (UTC)

It's not so obvious. You regulate laser diode output by controlling the current provided, not the voltage. Some very cheap laser pointers may rely on the internal resistance of the alkaline battery as part of the circuit that regulates the current through the diode. A lithium-ion battery has lower internal resistance than an alkaline one, and might provide higher current depending on the design of the circuit.--69.248.117.99 (talk) 05:43, 8 April 2011 (UTC)

Not something that personally interests me but since it's something I've seen in sites I visit I believe red lasers tend to be far more cost effective if you just want something that will light matches. I believe you can get random Chinese laser of indeterminate power that will nevertheless light matches for around US$30 presuming it can get thru customs. While you can get green and other colour lasers that will do the job, their primary advantage to the hobbyist would be for looks. I presume you're already aware such a laser as yours is very dangerous (probably (3B) and could easily blind anyone who views the light directly and already have appropriate safety goggles. Nil Einne (talk) 17:24, 31 March 2011 (UTC)

Avoid using Class III and Class IV lasers in your home! Your basic assumptions about safety are Just Not Good Enough! Powerful lasers can scintillate, reflect obliquely, and behave in nonintuitive ways. A proper optical laboratory will take much more precaution far beyond just "don't look into the laser beam." You need the laser to be firmly mounted on an optical bench where it can not shine anywhere unexpected. You need the work area (and the rest of the room) to be totally nonreflective; avoid specular reflective surfaces, avoid certain materials in the furniture and walls, and so forth. Even diffuse reflection of powerful laser light can cause permanent eye damage. By definition, Class III and Class IV lasers can cause you physical harm - and most can cause permanent damage faster than it takes you to blink or avert your eyes. Playing with lasers is like juggling knives - fun for a while, but your first "minor accident" will cause permanent and irreparable injury/damage. If you like powerful lasers, get involved with an optical research laboratory and learn the safety procedures, just like the experts do. Nimur (talk) 20:56, 31 March 2011 (UTC)

You can also use a laser from a DVD burner. Instructions here. — DanielLC 20:27, 31 March 2011 (UTC)

Identifying an old timey flying machine

I'm trying to find the identity or history of what I believe is a (failed) pre-Wright flying machine. It's well known to pop culture because it appears as stock footage in many, many movies and television shows, but I know nothing about it so I can only describe it visually.

It appears as though someone has taken an old car and attached a giant parasol to a vertical shaft through the center of the car. There's some sort of engine 'pumping' the parasol up and down. Apparently the principle is that air will be pushed to the sides during the up-stroke but downwards during the down-stroke.

Of course, in the familiar stock footage, the car does not fly. It just sort of bounces up and down on its shocks. I don't think its wheels even leave the ground.

Thanks APL (talk) 16:53, 31 March 2011 (UTC)

Was it the Flugan? --Jayron32 17:21, 31 March 2011 (UTC)

Or is it the first machine in this clip? Alansplodge (talk) 17:44, 31 March 2011 (UTC)

Here is some video of the machine in question. It is called the "John Pitts Skycar". This is the patent for its unique form of "flight". --Sean 17:43, 31 March 2011 (UTC)

Well done sir! A different movie clip of the same beast (with sound) here. On the upstroke the 60 vanes making up the "parasol" opened and on the downstroke they closed, hopefully creating downforce. Not enough apparently. It appears on our List of aircraft (P-Q) but there is no article yet. Alansplodge (talk) 17:45, 31 March 2011 (UTC)

Wow. Thank you. That's exactly what I was looking for.

I didn't even realize that the parasol "propeller" actually rotated as well as oscillated up and down. APL (talk) 18:16, 31 March 2011 (UTC)

That's a big engine under the thing. If they'd just hit on the standard helicopter rotor, I wonder if it could have taken off. (no comment on what would come afterward...) Wnt (talk) 20:01, 31 March 2011 (UTC)

That device probably had a poor power to weight ratio. I wonder if a modern engine could get that contraption to work? Googlemeister (talk) 21:11, 31 March 2011 (UTC)

It looks a bit like an early attempt at the eventually-successful craft called the Autogyro. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:34, 2 April 2011 (UTC)

What is fertilising the blossoming shrubs in England?

I have not seen any bees around, or any other insects for that matter, at this time of year. So what is fertilizing all the blossoms please? Thanks 92.29.127.125 (talk) 19:21, 31 March 2011 (UTC)

Just because you haven't noticed any bees or other insects doesn't mean they aren't around. Also, just because there are blossoms doesn't mean anything has been fertilised. The blossoms attract the insects to fertilise them so the plant can produce seeds. It's seeds that are proof of fertilisation, not blossoms (and even then some plants can produce seeds without being fertilised by insects). --Tango (talk) 19:28, 31 March 2011 (UTC)

Surely bees pollinate, not fertilize? APL (talk) 20:21, 31 March 2011 (UTC)

The terminology is fine: fertilisation "is the fusion of gametes to produce a new organism." Bees are the vector of fertilization for many plants. "Fertilizing" in the sense of supplying nutrients to a plant is the spurious usage. SemanticMantis (talk) 20:26, 31 March 2011 (UTC)

Plenty of bumblebees up here in Edinburgh. I assume if it's warm enough for them in Scotland, it's warm enough in England. 86.135.222.99 (talk) 21:59, 31 March 2011 (UTC)

We have an article on Pollination which explains quite a bit. There are some plants which don't even require other organisms to pollinate them, but also many other creatures other then bees can pollinate, including butterflies, moths, wasps, flies and beetles, even ants. Vespine (talk) 22:17, 31 March 2011 (UTC)

Although plants which wind-pollinate don't go to the bother of producing blossom with petals, nectar et al - they're purely for the benefit of insect-pollinators. Oak trees for instance have a rather dreary green catkin effort with which to spread their DNA about. Alansplodge (talk) 14:18, 1 April 2011 (UTC)

Though I suspect there are at least a few pollinators around, I'll point out that a match-up between the timing of flowers blooming and pollinators emerging is not guaranteed. The phenology of plants and insects has co-evolved for a long time, and both have something to profit by matching up for this mutualism. However, different species may be attuned to different cues (e.g. photoperiod vs. temperature), and these can get mis-matched, especially when we consider climate change. There is much ongoing research into the consequences of these matchings getting fouled up, see e.g. [1]. SemanticMantis (talk) 13:59, 1 April 2011 (UTC)

I saw my first bumble bee in Hertfordshire at the end of February and since then I've seen several species including the big white-tailed ones and little black ones that I don't know the name of. I've also seen lots of hoverflies and one Large White butterfly. Alansplodge (talk) 14:25, 1 April 2011 (UTC)

I have now seen a few bees. 92.29.115.116 (talk) 10:33, 4 April 2011 (UTC)