Wikipedia:Reference desk/Archives/Science/2014 August 28

= August 28 =

Anaplastic thyroid cancer and suffocation
Can someone please help me find a source stating a percentage (either a precise percentage from examining a range of studies, or at least a rough approximation) of anaplastic thyroid cancer patients who die by suffocation? Our article says "about half", but it's uncited (I'm trying to find a source for that section), and this PubMed article disagrees by saying "most". As far as I can tell, I can't access the sources that this author cites for that statement. Nyttend (talk) 12:50, 28 August 2014 (UTC)


 * Several reviews of the literature pop up on PubMed when "Anaplastic giant-cell carcinoma of the thyroid" is used as the search term. A cursory PubMed search seems to show most reviews do say "most," as opposed to "half," although (frustratingly) no paper I've found yet actually breaks proximate cause of mortality in ATC patients down by number.
 * Perhaps it'd be more effective for you to do the search and evaluate the usefulness of these reviews of the literature directly.
 * One thing I did notice is references in the literature to both an overall drop in incidence of ATC lately and recent reports that suffocation in ATC has become less frequent with modern multimodal therapy regimens (either doxirubicin used synergistically - as a radiosensitizing agent - along with radiotherapy, or surgery, chemotherapy and radiotherapy together) and emergent trachaeostomy.
 * Let me know if you'd still like outside help on this. loupgarous (talk) 14:49, 31 August 2014 (UTC)

Microscopic blackhole vs. Sun
Say you have a black hole with a mass of 600,000 metric tons and you collide it with the sun, and presumably it eventually falls to the core. What would happen? Would the tiny black hole consume the sun or would the slow accretion rate at the core due to nuclear fusion delay this process? 108.170.113.22 (talk) 16:18, 28 August 2014 (UTC)


 * For a black hole that is small enough, it will hardly eat anything at all. The Schwarzchild radius of 600,000 tonne black hole is much smaller than a proton.  As a result, it will have a very hard time eating any normal matter and its accretion rate would be extremely low.  In fact, rather than consuming the sun, it would probably evaporate due to Hawking radiation.  Dragons flight (talk) 17:31, 28 August 2014 (UTC)


 * The other factor to figure out is: can you collide the hole with the Sun so that it doesn't go straight through? I understand of course that any matter that actually gets in will average with its momentum to slow it down, and any increase in mass makes it harder to emerge against gravity on the far side, but how much will that be relative to the mass of the hole?  And a substantial portion of the mass would be lost as energy in the accretion disk as it passes through (or whatever, I guess it wouldn't be a disk inside the sun?) so it would be less than the total mass consumed.  Of course if it's big enough it'll eat the whole sun and not be parted with it, so there's a limit, but what that is... ? Wnt (talk) 17:57, 28 August 2014 (UTC)


 * If the interactions with the Sun are minimal, then it doesn't matter if it goes straight through as long as it is moving slowly enough with respect to the Sun when it starts. If it's moving slowly enough, then it's in orbit and will pass through the Sun again and again.  It won't be a Keplerian elliptical orbit because Kepler's laws assume the Sun can be treated as a point mass and actually when the thing's inside the Sun, the gravitational attraction is lessened; so its path won't repeat each time around, but if it's moving slowly enough to fall back in once, it will never escape. --70.49.168.18 (talk) 21:20, 28 August 2014 (UTC)
 * There will be relativistic complications, too, like Mercury's orbit with its apsidal precession, but much stronger.
 * One of the important questions is, from where the Black hole is dropped. From somewhere near Earth, or from a point closer to the surface of the sun?
 * In the latter case, the Black hole will spend a significant fraction of its time inside the sun, where it can absorb both energy and matter. In the former case, it would spend most of its time in the relatively cold near-vacuum of space, where it will emit more radiation than it can absorb.
 * Another factor is if it goes through the center of the sun, where the density, and therefore the growth rate, is extremely high. Growth means more gravity, which in turn means both a wider path through the sun where matter is "eaten" each time, and a lower Hawking temperature, which would reduce emitted radiation.
 * The equlibrium is unstable even if it exists, and I don't see if it exists at all: since the Black hole eats relatively "stationary" matter but emits in all directions, it will tend to slow down while it's absorbing matter, and its orbit will decay. The question is if it can settle down near the stellar core before it evaporates. - ¡Ouch! (hurt me / more pain) 07:02, 29 August 2014 (UTC)


 * 600,000 metric tons sounds like a lot - but it's about 1/10th the mass of the great pyramid of giza. We have built heavier ships than that!  So the gravitational pull at any reasonable distance from it is incredibly tiny.  The only chance it's got to absorb something is to either collide with it - or pull it in with gravity.   The force due to gravity gets stronger as you get closer - but you have to get a LOT closer to something with so little gravity for it to have much chance of pulling anything into it - and even if it can exert some kind of force, a lot of the material will spiral around it before falling in - and since our mini-black-hole is being pulled around by the sun's gravity, it's going to be a moving target.   Since it's also very small (smaller than a proton!), the odds of it colliding with another particle as it passes through the sun is pretty small...and the tiny gravitational field will fail to overpower the random thermal motion of atoms to any measurable degree unless it gets nearly close enough to collide with them.   So sucking in even a few atoms is difficult...and it has to suck in a LOT of material to allow itself to grow to a measurable degree.


 * But meanwhile, it's evaporating...


 * This article points out that the evaporation rate for a black hole is inversely proportional to the CUBE of it's mass. So small black holes evaporate very quickly.  It says that a 105kg black hole evaporates in about 1 second...so our black hole will evaporate in just a few thousand years.  So there is a race between accumulating mass and losing it.  Given that short evaporation time, one might wonder how such a small black hole would have survived for long enough to get here in the first place.  If it travelled interstellar distances to get here, the odds are good that it would have evaporated before it got here.   It would be an astounding coincidence if a larger, longer lived, black hole had evaporated down to 600,000 tonnes *just* as the thing got close enough to be a problem.   If it were moving fast enough to get here without evaporating, then it would shoot right through the sun and just keep on going.


 * SteveBaker (talk) 15:30, 29 August 2014 (UTC)


 * That was my impression also. But I have to wonder... is there any way that an evaporating primordial black hole might end up shooting its radiation more one way than another?  I mean, I'd think that if the hole were accelerating, less radiation might make it out "up" against the acceleration than "down", which ought to mean it produces a net thrust that causes acceleration...?  Can these holes "wake up" and start jetting around the stellar neighborhood like skyrockets when their end is nigh? Wnt (talk) 20:42, 29 August 2014 (UTC)


 * I don't think a black hole can be anything but utterly perfectly symmetrical. A rotating black hole can be slightly squashed at the poles - but I don't think any asymmetrical evaporation is possible. SteveBaker (talk)


 * Well, if acceleration could set up a feedback loop like that, I suppose it would be a sort of spontaneous symmetry breaking. To be clear, I've never heard any suggestion such a thing happens, but then again, I haven't heard the opposite either, which is why I asked. Wnt (talk) 02:02, 31 August 2014 (UTC)

Related question, would colliding a small black hole like that with an asteroid cause the asteroid to explode, or would the asteroid break up and form an accretion disk around it?


 * There is even less chance of interaction in that case. Even for a relatively sizeable black hole, the black hole will pass right through the asteroid with barely any interaction.   A sufficiently large one might drill a microscopic hole through the asteroid, but it doesn't seem likely that it would explode. SteveBaker (talk) 20:48, 30 August 2014 (UTC)
 * Well if it's giving off hawking radiation, there would have to be an interaction. ScienceApe (talk) 02:27, 31 August 2014 (UTC)
 * Yeah - I didn't say "no interaction", I said "barely any interaction". SteveBaker (talk) 16:19, 31 August 2014 (UTC)
 * Well no, it wouldn't be barely any interaction either. According to Black hole starship, hawking radiation should be above 25.6 gigawatts for a 600,000 ton black hole. So it should be quite a spectacular interaction. The black hole itself should look like a very small star. ScienceApe (talk) 20:08, 31 August 2014 (UTC)

You can estimate what will happen as follows. The Hawking temperature is an order of magnitude larger than the proton mass, which means that it will radiate photons, neutrinos, electrons, positrons, mesons and baryons. The lifetime of the black hole will thus be an order of magnitude smaller than what the standard formulas gove as these ignore the last states of the evaoporation when the temperature is high enough to emit ther particles. The emitted radiation of particles can be taken to be ultrarelativistic, you can easily estimate the radiation pressure some distance away from the black hole. Protons from the Sun's core then cannot move into the black hole because they are pushed away by the Hawking radiation. For a proton to enter, it cannot collide with the outgoing radiation, but using the cross section of protons with the outgoing radiaton, you can see that a proton coming in from infinity would on average have many interactions with the outgoing radiation. If you equate the effective pressure of the outgoing radiation as a function of the distance to the black hole, to the core pressure in the Sun you get an estimate of the radius of the bubble around the black hole that the Hawking radiation creates. This is a few micrometers. Count Iblis (talk) 19:31, 31 August 2014 (UTC)


 * This discussion is intriguing and, to me at least, amazing. But is this strictly theoretical or is there actual evidence that these microscopic blackholes are actually around?  Second question, if they are around, how common are they?  Thanks, CBHA (talk) 22:00, 31 August 2014 (UTC)


 * But there's nuclear fusion going on at the core of the sun. Would that not overcome the hawking pressure? ScienceApe (talk) 14:05, 1 September 2014 (UTC)

Much powerful induction
What kind of induction is always be much powerful an electromagnetic induction or magnetic induction? Why nuclear chain reaction is always based on the free exit of the magnetic induction, but not electromagnetic induction?--Alex Sazonov (talk) 16:21, 28 August 2014 (UTC)
 * Why scientific discovery of electromagnetic induction was preceded by a scientific discovery of the magnetic induction whether it is scientific regress?--Alex Sazonov (talk) 19:39, 28 August 2014 (UTC)

As far as I know the free exit of electromagnetic induction always determine the work of the electric current and the electromagnetic field--Alex Sazonov (talk) 17:10, 28 August 2014 (UTC)


 * Well there is Inductive reasoning and Mathematical induction both very powerful in answer to your first question. For the electromagnetic induction vs magnetic question, the equipment to show that is simpler, magnet and wire.  Thanks to the speed of light being so fast it is hard to get a high magnetic field strength for a time varying electric field.  It is much more straight forward to make a strong magnetic field with electric current, especially at the low rates of change that can be noticed by experimenter's eyes. Graeme Bartlett (talk) 02:41, 29 August 2014 (UTC)
 * Graeme Bartlett, why then, the magnetic induction generates all nuclear reactions rather than electromagnetic induction which is more much powerful than the magnetic induction? What is the force of the electric charge or the force of dynamics of the electric charge or more accurate what the inductance of the electric charge can be create a magnetic induction which is similar for a magnetic induction formed by nuclear reactions and how does it different from the electromagnetic induction?--Alex Sazonov (talk) 09:43, 29 August 2014 (UTC)

Is proven a scientific fact that all nuclear reactions are always formed under the influence of magnetic fields, or more precisely under the influence of magnetic induction, as well as proved a scientific fact that all nuclear reactions always form a magnetic fields, or more precisely form a magnetic induction.--Alex Sazonov (talk) 15:50, 29 August 2014 (UTC)

As I know, the powerfully doing sweep in the solar panels of the solar battery always being by the magnetic induction and not by electromagnetic induction. Magnetic excitation of the solar panels of the solar battery may be done by electromagnetic induction rather than by magnetic induction? Can the light of the sun create a powerful induction? Why the solar panels of the solar battery do not generate a force of energy (amperage - force of the electric discharge) of the dynamics of nuclear reactions, if the scientists said that the light of the sun always creates a powerful magnetic field (powerful induction)?--Alex Sazonov (talk) 08:18, 29 August 2014 (UTC)

Everything been nice, if the solar panels of the solar batteries will always have electromagnetic excitation!--Alex Sazonov (talk) 16:53, 29 August 2014 (UTC)
 * Solar panels are making use of light photons, or electromagnetic radiation. Electromagnetic radiation travels because the changing magnetic field induces an electric field, and the changing electric field induces a magnetic field.
 * I don't really know about nuclear reactions as you say. However nuclei contain protons and neutrons, both of which have a magnetic moment. The magnetic field close to the nucleus, or nucleons is very strong by every day standards.  Nuclear reactions will happen very fast, and then any magnetic filed will be changing very fast. So this can result in the formation of gamma rays. However I think you are making a false distinction between magnetic induction and electromagnetic induction.
 * By magnetic induction I expect you mean Faraday's law of induction :$$\mathcal{E} = -{{d\Phi_\mathrm{B}} \over dt} \ $$ which involves a circuit, and electromagnetic induction which is just more generalised: $$\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}} {\partial t}$$. Graeme Bartlett (talk) 22:36, 29 August 2014 (UTC)


 * Nuclear Physics always used a magnetic potential of elementary particles (elementary charges), rather than an electromagnetic potential of these physical objects, because the dynamics of atom (core) is always a magnetic induction, but not an electromagnetic induction. Nuclear Physics had yet to prove, that the powerful exit of the dynamics of the atom (core) may be an electromagnetic induction.--Alex Sazonov (talk) 00:27, 30 August 2014 (UTC)

As I know, the light of the sun never been form an electromagnetic induction, although the light of the sun had a powerfully magnetism, then what can form an electromagnetic induction in the solar panels of the solar batteries?--Alex Sazonov (talk) 23:07, 29 August 2014 (UTC)
 * All Faraday's laws of induction are been right only for cases of electromagnetic induction!--Alex Sazonov (talk) 23:16, 29 August 2014 (UTC)
 * The only difference I see is that Faraday's law assumes an electric conductor is there. But electromagnetic induction says the same thing, plus more, it also applies when there is no conductor there. Graeme Bartlett (talk) 12:15, 30 August 2014 (UTC)
 * Graeme Bartlett, where can meet the dynamics of electrical current in nature, only where can meet an electromagnetic induction, is it right?--Alex Sazonov (talk) 13:11, 30 August 2014 (UTC)
 * Graeme Bartlett, I been suppose that, an electromagnetic induction is always be a powerful dynamics of magnetic induction! Electromagnetic induction always is been more much powerful than a magnetic induction!--Alex Sazonov (talk) 18:09, 30 August 2014 (UTC)
 * Does in Nuclear Physics the force of the electric charge of the atom (core) had a constant before and after the free exit of energy?--Alex Sazonov (talk) 22:03, 30 August 2014 (UTC)
 * Can we assume that the force of dynamics of the electric charge in the nuclear and thermonuclear reaction is always negligible, so in nuclear physics, the force of dynamics of the electric charge in the nuclear and thermonuclear reaction had always considered to be constant?--Alex Sazonov (talk) 06:16, 31 August 2014 (UTC)
 * The electric charge certainly has a big impact on nuclear reactions. Consider protons mixed together,  They could fuse creating deuterium and positrons and antineutrinos, but you notice nothing happening because the protons repel each other. I don't know enough to answer your question. about how significant it is. I am sure it makes the different between what can happen or not in marginal cases, eg proton drip line. Graeme Bartlett (talk) 09:00, 31 August 2014 (UTC)
 * It was obvious that in the nuclear and thermonuclear reactions the mass of electric charge always had remains a constant before and after the free exit of energy (decay), that is always supports the law of conservation of masses and law of conservation energy.--Alex Sazonov (talk) 11:20, 31 August 2014 (UTC)
 * Was proved that, the nuclear and thermonuclear reactions could not creates a antimateria!--Alex Sazonov (talk) 11:39, 31 August 2014 (UTC)
 * Count a positron as antimatter. Take a read of Antiproton too. Graeme Bartlett (talk) 21:02, 1 September 2014 (UTC)

Link between the MMR vaccine and autism
Why does the pro-vaxxers' faction insist that there is no link between autism and the MMR vaccine. Medical journals with reputation have long refuted the harmlessness between the said vaccine and autism. MMR vaccines are dangerous. Is wikipedia paid by Merck oder/and Pfizer? --112.198.79.6 (talk) 17:33, 28 August 2014 (UTC)


 * Actually, papers in prominent medical journals have almost all concluded there is no link between the MMR vaccine and autism, and one of the few prominent papers to suggest otherwise was eventually retracted as a fraud. See: MMR vaccine controversy.  The vast majority of the medical establishment believes there is no link between MMR and autism.  Dragons flight (talk) 18:09, 28 August 2014 (UTC)


 * It's worth noting that there was actually a specific monetary incentive to find the link in the disputed studies, so if you're looking for something to be cynical about, this would be it. Wnt (talk) 18:35, 28 August 2014 (UTC)


 * Also see Anti-vaccinationist, Causes of autism, and MMR vaccine controversy. When "pro-vaxxers" insist there is no link between vaccinations and autism, it is because science has shown that there is no such link - the anti-vaccinationist's belief that there is a link can be traced to the 1998 publication of a fraudulent research paper. WegianWarrior (talk) 19:07, 28 August 2014 (UTC)


 * Yeah - this is very seriously *busted*. After that one (fraudulant) paper was disproved, all subsequent efforts (and there have been LOTS of them) to find a link between vaccinations and autism have failed to turn up a single shred of evidence.   Vaccination does not cause Autism.  What's horrifying is the amount of collateral damage that's been done to mankind by that one idiot and the people who continue to believe in his lies and falsifications long after it's been completely dismissed.   Children around the world have gotten sick, and a good number of them died for lack of a vaccinations that would have saved them.  Worse still, having a large pool of unvaccinated children-of-the-ill-informed not only affects the ill-informed and their children - but also the children who are still too young to get the vaccine who now stand a good chance of getting sick because of the greatly increased pool of unvaccinated children-of-the-ill-informed in the older age group.  This goes well beyond "this is my child and I'll decide what's right for him/her".  Continuing to believe in this nonsense is quite literally killing children...I can't imagine a more horrible thing to do.  I trust our OP will carefully review the evidence and not have the blood of innocents on his/her hands too. SteveBaker (talk) 21:13, 28 August 2014 (UTC)
 * Yes, I'm not sure about recent deaths from MMR vaccine avoidance, but Pertussis has centered squarely on the regions where anti-vaccine lunacy has the highest occurrence. The article states (with references) "Vaccination exemption laws appear to result in increased cases." SemanticMantis (talk) 21:34, 28 August 2014 (UTC)


 * The reason(s) of some people for denying a link between the MMR vaccine and autism might be found on related websites. Please see http://www.dmoz.org/Society/Issues/Health/Vaccination/Opposing_Views/Autism/.
 * —Wavelength (talk) 22:48, 28 August 2014 (UTC)


 * Also, there's recent research in I think the UK that shows autism signs before immunization age. --Wirbelwind( ヴィルヴェルヴィント ) 00:09, 30 August 2014 (UTC)

According to the CDC's page on measles http://www.cdc.gov/measles/about/complications.html, as many as 1/20 cases of measles result in pneumonia, which has a significant death rate in young adults and infants; as many as 1/1000 cases of measles result in meningitis, which is a vastly greater problem than autism. The issue shouldn't be "how many cases of autism MIGHT we prevent by denying our children MMR vaccine?" but "how many deaths from pneumonia and meningitis, and how many lifelong cognitive deficits or developmental delays can we prevent in kids who get measles by administering MMR vaccine?" The numbers (even if they are not as bad in developed countries as in less-developed countries) come down thumpingly in favor of giving the vaccine.

Even Mother Jones magazine, which is undoubtedly one place where anti-vaxxers might look for support of their views, published a series of investigative articles and even a UNICEF-authored graph (http://www.motherjones.com/environment/2014/04/how-many-kids-die-vaccine-preventable-diseases) which ended up supporting vaccination of children. To say the comment blogs under MJ's online versions of these articles were clogged by "Et tu, Brute?" posts from anti-vaxxers is a Level 5 understatement. loupgarous (talk) 15:37, 31 August 2014 (UTC)
 * And to address the second question, "Is wikipedia paid by Merck oder/and Pfizer?", no, wikipedia is not paid by merck oder/and Pfizer, Wikipedia is almost completely [run by unpaid volunteers], including the people who reply to you here. Most of us who value sharing knowledge, science, truth, reason and evidence and aren't paid a cent to write anything. Vespine (talk) 23:58, 31 August 2014 (UTC)

Antarctic Peninsula melt
If all of the ice on the Antarctic Peninsula (including the George VI, Larsen, and Wilkins Ice Shelves) melt, approximately by how much would the earth's sea levels rise? 174.88.192.23 (talk) 21:42, 28 August 2014 (UTC)

about 9 inches "The Antarctic Peninsula Ice Sheet contains enough water to raise sea level by 0.24m on full melting[9], and currently contributes 0.22 ± 0.16 mm per year to sea level rise[19]." http://www.antarcticglaciers.org/antarctica/antarctic-peninsula-2/ Not exactly the end of the world as we know it. Greglocock (talk) 02:27, 29 August 2014 (UTC)
 * but, I feel fine... -- Jayron  32  02:50, 29 August 2014 (UTC)
 * Also check Current sea level rise. The (I think) way more important question/problem will be what will happen to the system of Ocean currents around the world when the currentsystem at North Pole changes fast. So thermic aswell as ecologic balance there becomes a mess.
 * Ofcourse it is well known there have been big global temperature changes in earth history befor and we all think we know allot about Ice age but there is that one very important difference everyone seems to miss that "nature" always took 20.000 to 100.000 years for such changes (unless it was like what we today call "extinction event") but we will very likely cause this to happen in mere 200 to 300 years. --Kharon (talk) 03:41, 29 August 2014 (UTC)

I think that, it will change the climatic zones of the planet Earth, but level of global ocean will not change significantly. This is been so, because the natural magnetism of the planet Earth had always keeps in balance the mass of our planet.--Alex Sazonov (talk) 19:15, 29 August 2014 (UTC) Alex you may enjoy the article Earth's magnetic field which describes how the field has varied in the past, even completely reversed, and leaves records in rocks. 84.209.89.214 (talk) 19:54, 29 August 2014 (UTC) Thanks, I usually looking through the Russian version of the Wiki, because I have а small knowledge of English language.--Alex Sazonov (talk) 20:17, 29 August 2014 (UTC) May be a disasters when the natural planet magnetism have do keeping in balance the mass of our planet.--Alex Sazonov (talk) 20:36, 29 August 2014 (UTC)


 * I don't think there is any evidence that the magnetism keeps the planet's mass in balance, but there will probably be major disasters in electronic equipment (including satellites, the internet and electricity distribution) when the Earth's magnetic field falls close to zero as is expected sometime soon (in geological time) because the magnetism currently protects us from solar radiation.   D b f i r s   06:40, 30 August 2014 (UTC)


 * As far as I know, the natural magnetism of the planet Earth had always provides a balance of speeds and accelerations of movements of our planet.--Alex Sazonov (talk) 12:19, 30 August 2014 (UTC)


 * What makes you think that?   D b f i r s   12:26, 30 August 2014 (UTC)
 * It's the movement of layers in the Earth that causes the natural magnetism.   D b f i r s   12:28, 30 August 2014 (UTC)
 * I think so because, the gravity of our planet is always variable, as well as all the gravity of the Solar system are always variables.--Alex Sazonov (talk) 12:55, 30 August 2014 (UTC)
 * It sounds to me like you've been watching too many global disaster films like The Core or 2012 (film) or perhaps Collision Earth which amazingly Wikipedia does not have an entry for despite all the films in Category:Disaster films by country. Dmcq (talk) 14:11, 30 August 2014 (UTC)
 * What is been changed the orbit of our planet?

I don’t afraid to said that, the natural magnetism of our planet is been the basis of life stimulus for all in our planet!--Alex Sazonov (talk) 14:22, 30 August 2014 (UTC)
 * The above meets the requirements of a scientific hypothesis that can be tested by trying to breed generations of an organic life form, such as bacteria, worms, chicken or mice, behind a magnetic shield. Getting a result with Statistical significance strong enough to disprove the obvious null hypothesis would surprise many as extraordinary and likely lead to reprints of "Astrology: The Evidence of Science" by Percy Seymour (Lennard Publishing, 1988). Seymour's reasoning is that many kinds of Earth beings perceive and respond to magnetic cues, from ocean-dwelling bacteria that use magnetism to guide them downward to their food supply to the birds that navigate by the magnetic field. Human beings, too, have some inborn sensitivity to magnetism, and experiments have shown that many individuals can find north without a compass or any other obvious clues. Is magnetism the signal that calls the fetus from the womb? Is that fact the origin of astrology?...the forces generated by the planets in certain patterns are responsible for the reversal of the sun's magnetic field, which happens roughly every 11 years and kicks off the beginning of each new sunspot cycle. Source: "Dr. Zodiac" by Dawa Sobel, OMNI Vol. 12 No. 3 December 1989. 84.209.89.214 (talk) 18:14, 30 August 2014 (UTC)


 * The Earth's magnetic field is such an incredibly weak force compared to gravity, electricity (from lightning), chemical forces, etc., that it seems unlikely to have had much effect on early life. However, it does have the advantage of always pointing in the same direction (with a few exceptions), which does make it useful for navigation in animals and humans.  The first one-celled organisms would have been incapable of migration, and would just move with the currents, so would have little use for detecting the Earth's magnetic field. StuRat (talk) 23:31, 30 August 2014 (UTC)