Science desk
< January 4	<< Dec \| January \| Feb >>	January 6 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

January 5

I can directly control blood flow throughout my body

Is anyone else capable of doing this? For example, I can get an erection at will (without physical or mental stimulation) [this is not a joke I assure you]. I can also increase blood flow to my head, although the last time I tried (many years ago) it immediately triggered emotional problems. I can also increase blood flow to my eyes. Anyone familiar with this condition? I guess it's never too late to ask. Thanks.Phenylalanine (talk) 01:06, 5 January 2014 (UTC)[reply]

Biofeedback.

In the case of a penis the evidence is obvious, but I'm curious as to how you know that there is an increase in blood flow in your head or eyes. Are you actually measuring it with some instrument? Mitch Ames (talk) 01:20, 5 January 2014 (UTC)[reply]

Thanks for the link. It says that you can control your heart beat and blood pressure, etc. through biofeedback, but, my experience is more specific, I feel as though I can, simply by willing it, get my blood flowing to specific parts of my body (either my head, my eyes or my penis). No, I am not measuring it with any instrument. I simply feel the blood rushing to and pounding in my head. As for the eyes, I feel pressure in them and sometimes the eyes get red.Phenylalanine (talk) 14:17, 5 January 2014 (UTC)[reply]

I know I've fooled with circulation a bit - it's possible to view the increase directly as a visible redness around a sore you're trying to give more circulation to... on the downside, fooling around with alterations in brain circulation trying to (allegedly) improve/redirect cognitive power, I once managed to give myself a painless ocular migraine (which I never had before or since). Frankly, though, I suspect (based on scanty tests) at least half of all the effects are based on a simple voluntary increase in blood pressure rather than the targeted effect that one is looking for, and I think that a skeptical referee should demand evidence that there is a BP-independent effect. Your description of erection somehow reminds me of Taoist sexual practices (though it's not really the same thing). It also reminds me of one of the practices of the Kama Sutra, in which the man and woman were to remain motionless yet consummate. Wnt (talk) 05:11, 5 January 2014 (UTC)[reply]

Thanks Wnt.Phenylalanine (talk) 14:17, 5 January 2014 (UTC)[reply]

How can you will something without mentally stimulating it? Anyway, a man named Haridas may have gotten the same magic boner you do. Other fakirs (not necessarily fakers) have claimed similar things. InedibleHulk (talk) 05:35, 5 January 2014 (UTC)[reply]

On whom (Sadhu Haridas) we have an article, incidentally. Tevildo (talk) 11:50, 5 January 2014 (UTC)[reply]

Thanks for the link. What I mean is that I will it, but I don't think of anything in particular (like say a nude woman).Phenylalanine (talk) 14:17, 5 January 2014 (UTC)[reply]

Perhaps you're simply sexually attracted to the thought of yourself getting hard. Some sort of subconscious narcissism. Don't mean that as an insult, just something to consider. InedibleHulk (talk) 14:55, 5 January 2014 (UTC)[reply]

Also, you may be confusing blood flow with air pressure, if your eye method involves blowing with your blowholes closed. I used to blow various beverages out of mine that way to amuse my classmates. As I got older, it started to hurt too much and they moved on. Definitely feels like blood in there. InedibleHulk (talk) 05:43, 5 January 2014 (UTC)[reply]

Yikes, I didn't know that was possible. That's not the way it occurs in my case.Phenylalanine (talk) 14:17, 5 January 2014 (UTC)[reply]

It didn't exactly squirt out like a horned lizard (which certainly do use blood pressure). Just leaked. More just odd than yikes. InedibleHulk (talk) 14:55, 5 January 2014 (UTC)[reply]

I've found remembering a past mental state can do a few things, the most useful for me is I used to have hiccups sometimes which went on for a while but now I can stop them immediately by thinking of the feeling when they went away. Dmcq (talk) 11:28, 5 January 2014 (UTC)[reply]

I wish I could do that.Phenylalanine (talk) 14:17, 5 January 2014 (UTC)[reply]

Thinking about it, setting a mental state is probably the sort of thing that biofeedback is training people to do so there's good chance there may be a way to do it with that somehow. Dmcq (talk) 17:38, 5 January 2014 (UTC)[reply]

Here are a few other animals who seem to know your trick. Maybe you'll find some insight through them. InedibleHulk (talk) 15:00, 5 January 2014 (UTC)[reply]

Cool, thanks.Phenylalanine (talk) 17:18, 5 January 2014 (UTC)[reply]

Here's a weird hypothesis for your consideration (I doubt there's any data about it though! But I'm curious what you'd think of the idea): I suspect that the "emotion" of embarrassment/shame/shyness is purely the physical sensation of the constriction of blood vessels in the general region of Broca's area. I've noticed that for purposes of "GOTV" type activity that it seems to be possible to oppose this feeling directly by focusing on increasing the blood flow rather than decreasing it. I also suspect that the facepalm is a direct (though for most 'unconscious') response to this sensation... Wnt (talk) 16:21, 5 January 2014 (UTC)[reply]

Fascinating. Looks like you've been experimenting a lot with controlling your blood flow. In my case, the results have not been good. There was a time when I couldn't control the blood flow in my eyes and was feeling intense and uncontrollable waves of pressure in my eyeballs. Now, it mostly doesn't happen, although I can trigger it at will. Phenylalanine (talk) 17:18, 5 January 2014 (UTC)[reply]

Actually anyone can control the blood flow in their body, through techniques such as biofeedback (which I see you've dismissed), autogenic training and self-hypnotism. I don't think you're particularly special, just someone who's learnt how to do something on their own that other people can do too. --TammyMoet (talk) 16:22, 5 January 2014 (UTC)[reply]

Initially, I thought maybe it was some sort of Psi effect...Phenylalanine (talk) 17:18, 5 January 2014 (UTC)[reply]

I don't think he really dismissed biofeedback, but it's good to point out that it goes beyond whole-body parameters - if it in fact works on migraine (and there's a lot of people saying it does), that is very close to proof that it can affect specific blood flow patterns in the brain. For real proof I'd want to see fMRI (PMID 17508158) or PETT data, or some kind of proof of actual blood flow change - unfortunately I don't readily have access now to the PMID above - someone let us know if it's good? Wnt (talk) 16:41, 5 January 2014 (UTC)[reply]

Yes, the PMID is accessible. Thanks.

erm, whoops, I meant the article pointed to by the PMID, not just the abstract. Wnt (talk) 18:53, 5 January 2014 (UTC)[reply]

No, I do not have access to the full article. Phenylalanine (talk) 19:56, 5 January 2014 (UTC)[reply]

I think the broader context of this is that there is some reason to be skeptical about the absoluteness of the distinction between voluntary muscle and involuntary muscle. The distribution of blood around the body is governed by smooth muscle containing sphincters, much like those of the iris, pylorus, or inner anus. Now, subjectively, the action of any muscle seems to be a balance between "conscious" and "unconscious" factors. For example, if you look at something out of focus, you can open up your iris a little bit with little effort, but then the increased light makes you involuntarily close it back to its normal value. If you try to lift something really heavy, sooner or later you can't stand the strain and give up or drop it. It seems like the difference is more quantitative than qualitative, and so there ought to be some ability to control virtually anything connected to a nerve - why not? To children it seems all but impossible to control the anus; to adults it may seem next to impossible to open the pylorus and let food out of the stomach to avoid becoming dependent on a "little purple pill" - is there really a difference in the difficulty of these two things? I don't know. Wnt (talk) 22:01, 8 January 2014 (UTC)[reply]

Can fusion ever be a real, competitive power source?

I was reading another one of these articles - I feel like it could have been written in the 50s - about how with three different kinds of very expensive technical advances, and a few years, and some billions of dollars, nuclear fusion is finally going to reach the point where it is close enough to producing the power put into it that it will look encouraging.

I understand, of course, that from the beginning fusion has seemed tantalizingly possible due to the fusion bomb. Yet reading that article, I'm surprised to see it sounds like in any fusion bomb, most of the energy comes from fissioning of plain old uranium, with fusion just forming a good source of neutrons. And while of course fusion works in the Sun, it produces about the same energy per mass as a compost heap, AFAIR. None of this stuff really makes me think this reaction has a desire to shower us with infinite power if we just but understood it.

Now what I wonder is, what happens once it is capable of powering itself with a little left over? There are some things I wonder that are already mentioned in the ITER article, like, if fusion is actually carried out commercially, don't all the neutrons it produces make everything around it into radioactive waste, so that it's practically like using fission power? But there's one thing I still have to ask:

Has anyone, ever, seen a way that a nuclear fusion plant can ever, even in theory, actually produce as many total watt-hours PER DOLLAR INVESTED as solar panels, wind turbines, or geothermal? Is there any scenario where it really can stand in an open free market as the best source of power? Wnt (talk) 19:04, 5 January 2014 (UTC)[reply]

You're asking for predictions about the economics of future technologies. According to a sentence at the top of this page, we don't answer requests for predictions. Red Act (talk) 19:23, 5 January 2014 (UTC)[reply]

To be technical, I asked "has anyone ever seen...?" - I'm just looking for a sense of what a successful fusion plant is supposed to look like. I can't mentally picture giant lasers and hot plasma around something the size of a pencil eraser working out to a low capital investment. Wnt (talk) 23:09, 5 January 2014 (UTC)[reply]

Not something I know a lot about, but have you read the Fusion power article? - that seems to answer your question about nuclear waste. The other thing that strikes me is - would governments and researchers around the world be investing millions (billions?) of dollars in fusion research if there wasn't a high probability that the technology would be viable as a way of producing energy in the forseeable future? Richerman (talk) 19:32, 5 January 2014 (UTC)[reply]

Ah, but they're not, this is the point. The _total_ budget for ITER, split over the entire EU and six other countries, is €15 billion. The budget for HS2, in comparison, is £43 billion (€52 billion), and the actual cost is estimated at about twice that - which is just for one EU nation. If the governments of the world were serious about fusion, they'd be putting a damn sight more money into it than they are at present. Tevildo (talk) 19:52, 5 January 2014 (UTC)[reply]

Ah, the short-termism encouraged by our political system! Of course the British government are hiding their heads in the sand about our impending energy crisis anyway. However, after a little more reading I think this reference from the Fusion power article answers the question of possible the returns on the investment. Richerman (talk) 21:38, 5 January 2014 (UTC)[reply]

Thanks for pointing out this reference. But to be clear, what would a fusion plant generating the required 1 GW to be competitive look like? Does that mean all this radiation has to come out from one moderately small, incredibly densely packed area? Can any material survive in there? Wnt (talk) 23:09, 5 January 2014 (UTC)[reply]

The reaction itself would happen either suspended in vacuum by electromagnetic fields (e.g. ITER) or using an inexpensive physical support that is destroyed and replaced after each burst of energy (e.g. inertial confinement fusion, which can use something akin to fishing wire to anchor their target). The spot where the fusion reaction itself occurs is a very confined region that pretty much gets blown to hell, but the energy output is meant to be captured at the outer walls of a chamber which is much larger than the reaction region. For example, if a fusion reaction generates 1 GW, you might capture that energy over a sphere 20 m across, yielding 200 kW / m^2. That's a large thermal flux, but materials exists that can sustain that. (Though at present the best materials for lining fusion reactors due tend to wear out due to radiation exposure much faster than is likely to be economically reasonable for a hypothetical commercial reactor). Dragons flight (talk) 00:08, 6 January 2014 (UTC)[reply]

Lots of great answers here on all sides. So to be clear - tell me if I have this right - if I were to picture a scene set in a future fusion plant, they'd have a spherical chamber 10 m in radius (perhaps 6 industrial stories tall) with extremely thick layers of shielding around it (I'm not sure what would most resist being turned radioactive by the neutrons). I don't know how magnetic confinement could affect something at the center of a big empty sphere, but I can suppose every second a fuel pellet would drop from a long tube directly above the center, lasers would lock onto it, and they'd blow it away with ... unbelievable amounts of energy, but less than it is about to produce. It would then explode with the force of a ten-gallon can of gasoline well mixed with air, but without producing very much vapor relatively speaking so it would not produce as strong a shaking as a gasoline bomb; it wouldn't really rumble like a giant car engine from just the pellet's worth of gas and radiation pressure alone. To the point of view of the terrorist villain who we suppose has just run down the zigzag tunnel to the main access door, the light coming through the thick observation window in the access door is incredibly bright - not 1000 times the brightness of the sun on average but concentrated into a single instant, since most would be heat or ionizing radiation, but not that large a multiple less than that; it would I suppose very badly sunburn skin in a single flash? though with a delay for the person to realize it. He presses the button to extend the catwalk and it manages to stay intact despite the repeated blinding flashes of light just above it. After the next flash, he races forward with the Bomb held high, shouting his holy slogan; a flash takes him midway, staggering him and shattering every genome in his body, but he continues to move forward (?) blindly on the catwalk, guided by faith or luck, enduring another flash four times closer and stronger than the first, lurching desperately toward his goal - when, of course, I suppose the hero of the piece rushes in to open fire on him just before his crude sphere of uranium comes close enough to the central point, while his girlfriend at last successfully hacks the computer to prevent the last fateful pellet from dropping and exploding close enough to set off the bomb, incidentally saving the hero's life ... Wnt (talk) 04:29, 6 January 2014 (UTC)[reply]

Yes, that's a plausible image of what a laser induced inertial confinement fusion reactor could look like, though I doubt they would have windows. (Other types of reactors could have different layouts. For example, machines like ITER are toroidal.) The terrorist is likely to be disappointed though. Any reasonable engineer would make it impossible to enter while the machine was running. Further, for practical reasons the reaction chamber would almost certainly be maintained at a significantly reduced air pressure. That type of fusion machine doesn't require the strong vacuum of a tokomak, but a reduced atmosphere does improve laser function. As a result, breaching the door would flood the room with air with the likely side effect of shutting down the machine anyway. Beyond that the walls and floors are likely to be heated to the point of glowing and the radiant heat would be roasting for anyone who tried to enter. Nor would a pellet detonation be remotely survivable at close range, but then I guess having the terrorist's flesh boil and explode into vapor isn't a good movie ending. Dragons flight (talk) 19:00, 6 January 2014 (UTC)[reply]

Thanks! For the door and auto shutdown I can just say "hacking" and be done. You're right that the walls should be glowing cherry red with all that energy; while they could be cooled the higher temperature should be better for Carnot cycle extraction. The weak atmosphere is actually a plus for the scenario, because I can say when he breaches the chamber it is momentarily flooded with cold air; still, he's going to need one of those snazzy reflective fire suits from some old James Bond movie. Which brings us to the real sticky point, the pellet explosion - you are perfectly right that all the energy of a big can of gasoline is going to be radiated out and if you're fifteen feet away you're picking up, I dunno, 10 square feet out of 800 or about the same energy as half a liter of gasoline being sprayed on your flesh and set on fire. Ouch. I suppose the suit might reflect some, but I really don't have a good mental image of what a very abrupt lethal irradiation is like. Also, I suppose 1/80 GJ of energy carries 1/7 micrograms of mass, moving at 3x10^8 m/s is like nearly 50 grams hitting you at 1 m/s .. that's still less than a tenth of the power of being shot with a .22 bullet, still, I suppose you'd feel the force, while getting fried. Wnt (talk) 00:51, 7 January 2014 (UTC)[reply]

Power generation isn't all about $/kW - a lot of the problem is that you need energy on demand. Solar power only works in the day - and how much it makes depends on the weather. Windmills are also patchy producers of energy. Geothermal, tidal and hydo are all better - but they are not widely available. The joy of oil/coal/gas and nuclear energy is that you can throw a switch and you have power at any time in just a matter of minutes. When everyone wants to cook supper in the gap between two good TV shows, they need energy **NOW** and renewable sources are very poor at delivering that. There have been efforts to build large-scale energy storage systems that could store energy on sunny/windy days and give it back on dark/calm days - but they are expensive, inefficient and difficult to deal with.

Fusion power is a long-shot...but it's all we've got. Fission also works - but nobody really likes it and it has the capability of making a terrible mess - also, we'll eventually run out of fissionable materials. Fossil fuels quite clearly aren't usable for much longer. But there is enough deuterium in the world's oceans to provide humanity with power for millions of years...and more of the stuff available from the Moon and elsewhere in the solar system.

I disagree about the amount of energy that fusion could theoretically generate being really low - I don't know where you got those numbers - E=Mc² applies here. Experimental fusion plants aren't producing much excess energy - but that's because they're experimental.

The reason fusion research isn't well funded is a matter of politics - not science.

SteveBaker (talk) 22:47, 5 January 2014 (UTC)[reply]

"E=Mc²" applies... sure, but in this case, if "E" is the energy released by fusion, then "M" (the mass) in the equation is the mass defect of the fusion reaction, not the total mass of the fuel. Nimur (talk) 00:02, 6 January 2014 (UTC)[reply]

This is why I prefer a handy matter-antimatter reactor. StuRat (talk) 00:13, 6 January 2014 (UTC) [reply]

Whether it has to work is sort of irrelevant - question is, can it? Besides, I would think that geothermal heating could supply all our needs reliably; also, storage tech is vastly improving, so it's surely not the only option. Wnt (talk) 23:09, 5 January 2014 (UTC)[reply]

Well when you look at the options none are very high on assurance grounds. We need to put money into a whole host of options but we can't put all our money in, we have to live today. The best bet is to put in money so the research is done efficiently rather than trying to do a moon shot sort of business. Other things competing are for instance having DC lines going from temperate zones to desert areas with solar energy and around the world - which would be a huge engineering effort and beset by political problems, carbon capture and storage to try and gain a bit back from global warming - not exactly hopeful but has to be tried, fast breeder reactors - but who's keen on that?, or power from waves - this has a similar long and not very successful history. Fusion power has got some promise and even if it takes another fifty years I certainly believe it is a worthwhile project. Dmcq (talk) 23:28, 5 January 2014 (UTC)[reply]

Here is an example of a study trying to make educated guesses about the economics of fusion power. In their model, commercial fusion energy first becomes available after 2040 with a cost per kWh about 3 to 4 times higher than competitive fossil fuel technology (driven by large upfront facility costs). By 2100 they imagine fusion costs come down so that they are only about 1.5 times the cost of fossil fuel. In other words, they are assuming that through the 21st century, fusion energy would require subsidies in order to competitive with fossil fuels (or equivalently, fossil fuels would have to be penalized based on carbon emissions). They also assume that fusion is more expensive than solar, wind, and traditional nuclear options during the entire 21st century, though the cost penalty comes down towards the end. Of course, not all choices about energy mix are driven by electricity cost. Factors such as pollution, carbon emissions, constancy of power supply, and incremental deployment costs are also important. Over the long-term, fusion seems a relatively safe and sustainable form of baseload power, which makes its development interesting, but it isn't magic and it seems unlikely that fusion will be so cheap at any point during this century that people would abandon alternatives forms of power for purely economic reasons. Dragons flight (talk) 23:37, 5 January 2014 (UTC)[reply]

I'll throw in another wrench to the works. Fusion research has two epicenters in the United States: at Sandia National Laboratories in New Mexico, and at the National Ignition Facility in Livermore, California, which is just a twelve-minute flight from my home.

Both of those facilities are funded by the Department of Energy. Neither is an ordinary National Laboratory. Both facilities are, very clearly and openly and publicly, what the Department of Energy calls nuclear weapons laboratories. For example, the top line of the Mission Statement at Sandia's website says:

“

Sandia's primary mission is ensuring the U.S. nuclear arsenal is safe, secure, and reliable, and can fully support our nation's deterrence policy. Sandia is the engineering arm of the U.S. nuclear weapons enterprise. We weaponize the nuclear explosive package to create an effective and sustainable nuclear deterrent.

”

— Sandia National Laboratories Mission Statement

And the same, at Livermore's NIF website:

“

How can we ensure the nation's security without nuclear weapons testing? Maintaining the U.S. nuclear weapons stockpile as a deterrent against foreign aggression has been a mainstay of national policy since the end of World War II. No new nuclear weapons are currently being built, however, and the existing weapons cannot be tested under a nuclear testing moratorium established by President George H.W. Bush in 1992. To ensure the continuing reliability of the nuclear stockpile, Lawrence Livermore and other national laboratories are developing sophisticated supercomputer simulations to determine the effects of aging on nuclear weapons components as part of the National Nuclear Security Administration's Stockpile Stewardship Program. NIF will be able to provide data for those simulations by replicating the conditions that exist inside a thermonuclear weapon.

”

— Mission statement for the National Ignition Facility and Photon Science programs

So, when Wnt reads and links a fantastic piece of science published in the journal Nature (or rather, on its website Nature News), he may be missing a little bit of context (perhaps he's not reading between the lines). That experiment for fusion-power is part of a weapons laboratory. Research physicists do not work at Sandia because they are developing the next generation of civil energy supplies. There are dozens of other facilities and national laboratories funded by the Department of Energy where research physicists study the fundamental science to ensure a reliable civil energy supply. At Sandia, the physics is all about nuclear weapons.

Since there are many many international treaties that prevent the United States from pursuing active programs that verify weapons integrity by detonation-style nuclear testing, there is a need to find alternative methods to verify that our warheads are still functional. The best way to verify that they still work is to blow one up every now and then. But that's no longer allowed: there have been a series of treaties, including the START II agreement.

Because our nuclear stockpile still exists, and it is populated mostly by thermonuclear weapons that were built in the late 1980s, and because international agreements prevent the Department of Energy from detonating any weapons to test them, labs like Sandia and the NIF have no choice but to simulate weapons.

So when you see an enthusiastic physics publication proclaiming the future of fusion energy, and you see that it came from a weapons lab, the message you're really supposed to take away is this: the United States still has thermonuclear weapons capabilities, and it's honoring its international commitments by not blowing any up, but this is a pleasant reminder that the capability still exists.

Steve Baker probably nailed it when he said that this publication - this entire area of research - is "a matter of politics - not science."

Nimur (talk) 00:27, 6 January 2014 (UTC)[reply]

That was my feeling going in, and I'm still prone to agree, but still the sources above showing a steadily increasing triple product and arguing for eventual possible viability carry some weight. Plus I have to wonder whether reactions in fusion reactors without uranium present really give all that much useful information about fusion bombs, and also, what does the EU get out of it? There is, after all, another conspiratorial explanation available which is just that some people are going to lobby hard to keep their jobs. But I'm still skeptical of fusion's viability, because those arguing for its eventual economic role still use an optimistic model and seem to treat it as a clean energy source, despite the problem of induced radioactivity, which might make their numbers inapplicable. Wnt (talk) 19:06, 6 January 2014 (UTC)[reply]

There are only 36 isotopes with half-lives between 1 year and 1 million years. Isotopes that have longer or shorter half-lives than that don't tend to be a long-term waste problem because they are either so unstable that they burn off quickly, or so stable that they aren't very dangerous. Of those 36, 15 are at least as heavy as uranium, so you can avoid those simply by not having any really heavy elements in your reactor design. After that you go down the list and start figuring out what materials you have avoid in order to minimize the production of problematic isotopes. One of the things you quickly figure out is that nickel is not a good idea, and likewise for molybdenum, niobium, copper, and nitrogen. Thankfully iron is okay, so we can use steel, but you end up looking at steels with unusual compositions using elements such as chromium, manganese, titanium, tungsten, and vanadium, instead of alloys normally involving nickel / molybdenum. Most of the radioactive danger from fission plants comes from the fuel, and that's the waste people talk about generally. However, with fission you also have induced radioactivity of various structural elements, that you want to keep to a minimum. For the most part, we already know how to do this so that the non-fuel elements are safe enough to qualify as low or medium level radioactive waste, which are suitable for shallow burial in existing land fills that are specially licensed for the disposal of such wastes. Obviously avoiding sources of long-lived induced radioactivity is a major concern, but it is likely to be a surmountable problem. You'll still have a variety of low-level radioactive wastes to worry about, but well-designed fusion plants should be able to avoid creating the highly dangerous kinds of wastes that are associated with fission products. It is also worth noting that fusion plants don't have a failure mode that can lead to an uncontrolled meltdown, which greatly reduces the risk of uncontrolled radiation releases. Dragons flight (talk) 20:17, 6 January 2014 (UTC)[reply]