Wikipedia:Reference desk/Archives/Science/2016 July 13

= July 13 =

medication side effects appearing long after starting the drug
Suddenly last fall I began to suffer from these debilitating symptoms 2-3 times a week: sudden, profound unease and general weakness; unsteady, clumsy, sluggish, slow, lightheaded, woozy, cloudy of mind. They lasted a few hours, but worsened if there was no opportunity for sleep. After a few hours it was over and I felt fine. Several doctors couldn't figure it out. Finally, one suggested a medication review, and it turned out that these and other problems I had been having were side effects of the drug Requip, which I had been taking for over a year beforehand. I stopped it, and the episodes went away. How can it happen that such side effects should suddenly arise so long after starting the drug? --Halcatalyst (talk) 14:28, 13 July 2016 (UTC)
 * We cannot provide medical advice here. Please contact your doctor. --OuroborosCobra (talk) 14:55, 13 July 2016 (UTC)
 * I disagree that this is a request for medical advice. The OP makes clear that the effects described have already been addressed by a doctor, and solved by appropriate action, i.e. ceasing to take the drug causing them. The OP's question inspired by this is more a physiological one about why a drug's side effects might start to appear only after a protracted period of taking it, rather than immediately as one might expect. Neither the above-linked short article nor the more extensive adverse effects addresses the question. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 15:07, 13 July 2016 (UTC)
 * Adverse drug reaction doesn't help much either, and I agree that it is an interesting question. I have certainly had a significant reaction to a medication which occurred a few weeks after I started and which was acute and my doctor could not explain; that medication is now one I always list to avoid.  I also agree that the question is not a request for medical advice but is about a medical phenomenon which has applicability beyond the OP.  EdChem (talk) 15:30, 13 July 2016 (UTC)
 * When you look at the Ropinirole article, note the reference to CYP1A2. That enzyme is induced by eating things like broccoli; other drugs might inhibit its activity, or burden it with other things to do.  So if you were eating broccoli fairly regularly for a while, a dose of ropinirole that didn't cause harmful side effects then might become a higher dosage with troublesome effects if you stopped.  This is just an example of how this could happen; there could be a lot of potential causes, some worrisome, and I certainly can't diagnose the issue blindly.  Biology is complicated! :) Wnt (talk) 16:27, 13 July 2016 (UTC)
 * Do not attempt a diagnosis. Response to this question should go no further than citing the article about Ropinirole (tradename Requip) that contains the only sourced information we can give about its side effects and a lawsuit in November 2012. AllBestFaith (talk) 16:30, 13 July 2016 (UTC)


 * The OP's question, despite the prologue, is;"How can it happen that such side effects should suddenly arise so long after starting the drug?" That's not an improper question.  The mechanisms will differ, but Lisinopril, for example, is known to cause a chronic cough, and various statins cause muscle weakness, both with an onset delayed by days or months.  Dozens of drugs have side effects that depend on long-term use.  Your doctor, specialist, or pharmacist should be able to answer questions we can't answer due to policy. μηδείς (talk) 18:13, 13 July 2016 (UTC)


 * I gave my experience merely as an example; perhaps I should have made that clearer. What I would like to know is what factors might play into a drug suddenly generating new and perhaps serious side effects long after it swas firsst started.--Halcatalyst (talk) 03:32, 14 July 2016 (UTC)


 * Really, we don't know. The body is an enormously complex system, and there are many things we don't know about it. This is why clinical trials and post-marketing surveillance are important in assessing the effects of a drug. One class of things we do understand fairly well are carcinogens; with these, it's the gradual accumulation of DNA damage over time that can lead to cancer. Most cancers develop from numerous mutations, and your body has DNA repair mechanisms, so a single mutation is generally not a problem (and indeed, they happen all the time in your body). That's why you don't get cancer from smoking a single cigarette. --71.110.8.102 (talk) 04:37, 14 July 2016 (UTC)


 * Thank you all for your responses. I was curious as to whether these was an explanation, since my case seems very strange indeed. Most drugs, I suppose, have effects in other parts of the body than are specifically targeted. So it is indeed very complex. --Halcatalyst (talk) 14:25, 14 July 2016 (UTC)

Why faster than light travel is impossible
In short is the basic reason for why FTL travel (and communication) is impossible is because of the relativity of simultaneity? In that if there was an object moving FTL, it would result in a causality violation in which there exists a reference frame where the object reaches its destination before it ever left? And this holds true for any FTL manifestation, i.e. wormholes, instant teleportation, etc. ScienceApe (talk) 15:43, 13 July 2016 (UTC)


 * Well, looped causality isn't really a "disproof" since there are hypothetical things like a Tipler cylinder that appear to work out with it. But yes, a light cone tipped any further than light speed will appear to have reverse time from some other frame.  That doesn't really prove a loop though, because even though the events appear to occur future to past, they don't do so in a non-spacelike way from any slower than light frame unless the traveller's light cone is tipped more than 90 degrees, i.e. moving into the past.  But the thing is if one traveller can go faster than light, then another can do so, linking those spacelike events into a reverse timeline.  Provided, that is, there isn't some absolute frame of reference in the local area that no FTL traveller can move reverse in time relative to - you could have basic special-relativity FTL without time loops as long as they are not crossing this.


 * The far more compelling argument against FTL is simply that the faster you go the more energy you have, without limit; you have to cross a point of infinite energy to go past lightspeed. There are numerous other paradoxes with any sort of acceleration.  So it has to be some idea that involves skipping past the speed of light without any finite rate of acceleration, which is possible but harder to picture. Wnt (talk) 16:19, 13 July 2016 (UTC)
 * Apparent FTL is not excluded by general relativity, see the article Faster-than-light. However transversable wormholes are a common element only in science fiction. AllBestFaith (talk) 16:21, 13 July 2016 (UTC)
 * The increase in relativistic mass as a body approaches light speed is not nearly as a strong an argument against FTL than the causality violation. It just makes it impossible to accelerate to light speed conventionally. But we can e.g. communicate at light speed using photons, so it's just as easily imaginable that there is some other unknown principle to communicate, and possibly travel, at higher than light speed - science fiction is full of such devices, some of which have some theoretical support in physics (e.g. wormholes). But any kind of FTL communication results in causality violations, regardless of mechanism. I'd say the causality principle is fairly well established at least on the macroscopic level, so this general argument is stronger than an argument that just rules out acceleration of massive bodies to light speed. --Stephan Schulz (talk) 16:59, 13 July 2016 (UTC)


 * We don't know if FTL travel or communication is possible or impossible. Current physics tells us that no application of energy can ever accelerate a massive object to FTL speeds.  General relativity allows us to contemplate wormholes, closed time-like curves, Alcubierre drives and other configurations of space-time that would permit (and in fact require) FTL travel, but it is unclear if those space-time configurations are actually meaningful descriptions of reality or just interesting bits of mathematics.  For example, even though wormholes are valid solutions of the equations of general relativity, it may well be that there is no physical way to create a wormhole.  We don't know of any way, even in theory, to punch useful holes in space-time and create wormholes.  It is true that FTL communication will necessarily violate human notions of causality (e.g. tachyonic antitelephone).  However, it is unclear whether or not physics actually has a problem with that (see causality (physics)).  In general, humans perceive cause and effect and an arrow of time, but physics rarely specifies things that way.  Most physical equations are perfectly happy under time reversal.  Does nature care which events we label as "effects" and which are "causes"?  It isn't really clear.  Maybe FTL travel is impossible because it violates causality, or maybe the belief in causality is itself a misconception the same way that quantum mechanics revealed that many aspects of our human intuition are not absolute features of reality.  Even further, time might be an illusion, such that all events past and future are fixed and unalterable even if time travel is possible (Eternalism).  Or alternatively, the universe may be constructed in such a way that time travel is allowed but temporal paradoxes are intrinsically impossible (Novikov self-consistency principle).  Ultimately, we don't know.  Unless we actually achieve FTL travel, hypotheses about the consequences of FTL travel are likely to remain in the realm of speculation.  Personally, I wouldn't use arguments about causality as a strong reason to rule out FTL travel, because it isn't very clear how real or important causality ultimately is.  For me, the bigger issue is that general relativity doesn't appear to provide any mechanism by which space-time configurations involving FTL travel can be created provided that one must start from ordinary flat space.  Maybe a future theory of quantum gravity or some such thing will reveal a way to achieve FTL travel.  Or maybe a very clever person will figure out how to achieve FTL travel in conventional general relativity, but right now FTL seems impossible because physics as we understand it doesn't seem to provide any mechanisms by which FTL travel can be constructed using ordinary matter and space.  Dragons flight (talk) 19:02, 13 July 2016 (UTC)
 * I'm not entirely sure I follow. If the universe doesn't care about our conceptions about causality, then surely you should be able to do a FTL round trip and come back before you ever left, giving rise to two of you, then kill yourself before you ever left i.e. grandfather paradox. Since that's impossible, it stands to reason that FTL travel is impossible. ScienceApe (talk) 20:02, 13 July 2016 (UTC)
 * Not necessarily. For example, time travel in a framework of eternalism, would say you can go back in time but not change anything because your time traveling self was always already part of the timeline.  Its the 12 Monkeys versus of time travel, the time traveler goes back, and appears to influence events, but everything they did was exactly what already transpired and was part of history before they traveled back in time.  This is one version of time travel that violates causality but doesn't necessarily violate physics if you believe eternalism is the right interpretation of physics.  General relativity and things like wormhole-based time travel tend to be consistent with an eternalist interpretation.  In this worldview, the actions of the time traveler won't prevent the traveler from going back in time (so a grandfather paradox is impossible).  Novikov self-consistency principle is similar, and sometimes misunderstood as eternalism, but strictly speaking only really says that the universe abhors a paradox.  In that worldview, time travel could be possible, and you could alter the past, but only in ways that would not lead to paradoxes (like preventing your future self from traveling back in time).  Lastly, maybe the universe doesn't actually care about preventing paradoxes, and allows some form of alternate timeline / multiverse craziness.  If someone invents FTL travel we can test it and see what happens.  If FTL travel is possible, a universe that obeys eternalist principles but is no longer strictly causal as humans usually understand it would probably be the easiest to reconcile with existing physics.  Dragons flight (talk) 20:43, 13 July 2016 (UTC)
 * But what would stop you from killing yourself? There would have to be some physical force to prevent that from ever happening. The only thing that could prevent that would be the impossibility of traveling back in time in the first place. Alternate universes would presume that every time you travel back in time you create another universe, but then wouldn't it stand to reason that the energy it would take to travel FTL would equal the energy to create a whole universe in the first place, making it impossible? ScienceApe (talk) 21:21, 13 July 2016 (UTC)
 * You're assuming free will, a concept subject to a great deal of debate. All of these causality issues are encountered in garden-variety precognition with no actual time travel required.  For my part I have suggested that the causality violations are themselves the actual source of free will, its very definition really as an uncaused causer, and as such it cannot contradict them. Wnt (talk) 23:10, 13 July 2016 (UTC)
 * Precognition is the time travel of information. Foreseeing that a ball will drop if you let go is just a forecast. Holy shit, the ball fell! My forecast was right! Sagittarian Milky Way (talk) 03:03, 15 July 2016 (UTC)


 * As Wnt alludes to, an eternalist perspective on physics is one in which free will doesn't exist and never existed. Free will, like the passage of time itself, would merely be an illusion.  All events past, present, and future are already fixed.  An individual's personal history might appear to time travel, and thus violate causality as we perceive it, but they never really had the freedom to change anything.  If time travel is possible, then the time traveler's past actions were always a fixed part of history.  Dragons flight (talk) 04:48, 14 July 2016 (UTC)


 * So that's like bringing back the old deterministic clockwork universe after quantum mechanics was thought to refute it? That for whatever reason, the universe must have these specific random quantum fluctuations and no others are possible. Look at an electron today and change what the unchangeable future will be! Run naked in the street screaming bloody monkeys and do something inevitable today! Sagittarian Milky Way (talk) 06:22, 14 July 2016 (UTC)
 * Actually that's not what I suggested at all. A situation with loops of causality is one in which the universe can have multiple solutions, and there is no way to calculate which is the real one without actually looking to see.  That is the very essence of free will - not just a random roll of the dice, but not the consequence of any past or future event.  You can't change the future or the past, yet by some means that option has been selected in a way that the laws of physics cannot account for - which is the link to the supernatural that people intuitively seek when considering what free will is. Wnt (talk) 11:17, 14 July 2016 (UTC)


 * No actually I'm not assuming free will. For example if we assume that there is no free will in our universe, there is still nothing stopping one from pursuing their desires right now. So if one were properly motivated and capable of killing, they would do it even in a "no free will" universe. So if you're going to say that it's impossible to kill yourself when traveling back in time, there has to be some force that physically prevents that from happening. The only thing that prevents such a thing is the impossibility of traveling back in time in the first place. ScienceApe (talk) 15:57, 14 July 2016 (UTC)
 * Consider the double slit experiment. You measure which slit a photon passes through, and that changes where it comes out.  But it doesn't just change where it will go - you now know that the photon passed through the space between the photon source and the slit before you did the measurement.  So the measurement in the future changes -- erm, I mean causes; I would argue it always was this way -- the distribution of the photon in the past.
 * In this case, you've done a very elaborate, very thorough measurement of the position and velocity of the particles in the future. Now, given what you know, you work out the most probable solution that is also compatible with their positions in the past - just as you work out the location between source and slit in the first example.  The "randomness" of quantum mechanics allows for a solution that is compatible with all boundary conditions, past and future.  I suppose it might also establish an energy requirement for making the connection, come to think of it, which would be very substantial for a physical loop in spacetime with a huge number of simultaneous observations to be reconciled? Wnt (talk) 16:23, 14 July 2016 (UTC)
 * I see what you're trying to say but there's a big difference between your analogy and people. People aren't photons. There's no evidence that the universe is determined, on the contrary all the evidence points towards the conclusion that FTL travel is impossible. So then why are we entertaining a FTL and therefore time travel as a possibility when everything we know about the universe tells us that it's impossible? Reality has a tendency to converge on truth. If something is true, the more we learn about the universe, the more likely it is to be even more "true". Everything we learned about the universe has converged upon the truth that FTL travel/communication is impossible. Even things that seemingly occur FTL like entanglement forbid us from communicating FTL anyway. Occam's razer applies here. The explanation that makes the fewest assumptions is most likely to be true. In order for FTL travel/communication to be possible then we have to assume (with no evidence) that time travel is possible. Then we have to assume (with no evidence) that time travel either creates alternate universes or that even if you travel back in time, you can't kill yourself before you go on your FTL spaceship. All the evidence points towards FTL travel/communication being impossible, and that explanation makes the fewest assumptions so it's most likely the correct conclusion. ScienceApe (talk) 19:20, 14 July 2016 (UTC)
 * I lack confidence in Occam's razor. By your argument, the simplest explanation for why no birds fly in space is that you can't fly in space.  And as I said, these issues come up with precognition anyway, so saying you can't travel in time isn't really sufficient - you have to also maintain that it is impossible for the past to remember the future, which is an arrow of time argument that is not at all obvious to be 100%, especially when aberrations start piling up. Wnt (talk) 02:49, 15 July 2016 (UTC)
 * No, Occam's razer doesn't posit the simplest explanation, it posits the explanation that makes the fewest assumptions. You can have very complex explanations all you want as long as there's evidence backing it up. There's no evidence backing up FTL travel, let alone time travel. Saying time travel is impossible is sufficient when all evidence points towards that conclusion. On the contrary, you have to wonder why you're so reluctant to say FTL travel is impossible? It's because we want FTL travel and communication, who doesn't? But we have to separate our desires from the facts. ScienceApe (talk) 05:09, 16 July 2016 (UTC)
 * This has nothing to do with a desire for FTL; as I said, the paradoxes pertain to precognition anyway. I mean, somebody smashes into your car mirror and you get furious because you can't believe that the same damn day you replaced it it was smashed again ... then you remember this is the first time.  You spend two weeks driving around with a broken mirror, try doing an improvised replacement in the forlorn hope that the twat who smashes it again can be lured in before you've paid to have it replaced, but nothing doing.  Eventually you give up and get it replaced and sit around waiting to hear the idiot crash into it.  That kind of stuff.  There's no pretending the issue can be swept under the rug by saying FTL is impossible. Wnt (talk) 13:42, 17 July 2016 (UTC)


 * Assuming Lorentz invariance faster than light travel is problematic as pointed out in the answers above. Alternatively, one can consider the possibility that Lorentz invariance may not be exactly valid, but there are strong constraints on Lorentz invariance violations. Count Iblis (talk) 21:40, 13 July 2016 (UTC)