Wikipedia:Reference desk/Archives/Science/2020 May 22

= May 22 =

Digestion
Regarding digestion I've asked biology people, what % of the food we eat is converted to energy? And the rest as waste. Some say 10%, some say 25%, depending on whether it's meat or vegetables and such. But if you asked a physics professor, they'll say, more like 0%, because food has to travel towards the speed of light to convert into energy. Does anyone disagree with this? (I previously asked this q years ago.). Well, this is the closest thing I can think of for applications heh. 67.175.224.138 (talk) 05:54, 22 May 2020 (UTC).
 * "Food has to travel towards the speed of light"? What on God's green earth does that mean? ←Baseball Bugs What's up, Doc? carrots→ 15:14, 22 May 2020 (UTC)
 * Do you know of a way for food to convert to heat energy by travelling significantly slower than the speed of light? If not, then my premise still stands, all the biology gurus are wrong, so more like 0% of the food we eat is converted to energy. 67.175.224.138 (talk) 15:46, 22 May 2020 (UTC).
 * Yes. Enthalpy of reaction releases heat energy without approaching the speed of light. See also bond-dissociation energy, chemical energy, adenosine triphosphate and tons of other processes. Let me ask you a different question; if you think 0% of food is getting us energy, how do you think we have energy? --OuroborosCobra (talk) 16:32, 22 May 2020 (UTC)
 * Well, energy can't be created nor destroyed. So if the mass is the same, then the energy came from prior energy, not from prior mass. 67.175.224.138 (talk) 02:06, 23 May 2020 (UTC).
 * Try lighting a match as a demonstration. ←Baseball Bugs What's up, Doc? carrots→ 08:46, 23 May 2020 (UTC)
 * If you think it came from prior energy (and you are more correct here in saying that, since we are basically talking about releasing energy, not converting mass to energy), why would you think that any food particles have to be traveling at any speed, let alone near the speed of light? --OuroborosCobra (talk) 19:22, 24 May 2020 (UTC)
 * Well, if the speed of light is 186,000 miles per second, and speed of light mass is 100% converted to energy, then does travelling 1% of speed of light, means 1% of mass is converted to energy? 1,860 miles per second? = 6.7 million mph, so looks like food being kept is in the 99.9999%? 67.175.224.138 (talk) 06:34, 25 May 2020 (UTC).
 * No. ←Baseball Bugs What's up, Doc? carrots→ 06:58, 25 May 2020 (UTC)
 * It's complicated and there is no simple answer. For a start it depends what you eat and your lifestyle. I suggest you study our article on food energy and come back with a clearer question.--Shantavira|feed me 15:22, 22 May 2020 (UTC)
 * Chemical energy does not require a nuclear reaction. But either you already knew that and are just making a science joke (which I always appreciate, but needs to be more clearly identified as such in this communication medium), or else "now you know". A more interesting question (in a teaching sense) is to take the amount of energy that is demonstratably released from a foodstuff, calculate how much less it weighs. And then how close science isn't to being able to measure that value. DMacks (talk) 16:00, 22 May 2020 (UTC)
 * Why should it weigh less, though? We are talking, generally speaking, of conversion between potential and kinetic energy, and not between mass and energy. --OuroborosCobra (talk) 22:30, 22 May 2020 (UTC)
 * https://wtamu.edu/~cbaird/sq/2013/10/21/why-is-mass-conserved-in-chemical-reactions/ Basically, bonds have mass. --Khajidha (talk) 11:54, 23 May 2020 (UTC)
 * Baseball Bugs already touched on this slightly as have other commentators but to be more direct, I think you may have misunderstood Mass–energy equivalence. The equation, $$E=m\,c^2$$ does not mean things need to travel close to the speed of light for energy to be released. Nil Einne (talk) 14:30, 23 May 2020 (UTC)
 * Does traveling at the speed of light (approaching) means mass is lost (approaching) at 100%? Does 1% mass is lost at 1% the speed of light? 1% of 186,000 mph is 1,860 mph, still faster than electrical signals in our body that goes 250 mph. So it seems to me, the answers are in the 99.99...% of mass is kept. 67.175.224.138 (talk) 02:07, 24 May 2020 (UTC).
 * Actually, mass increases as you increase velocity. In a sense. https://galileoandeinstein.phys.virginia.edu/lectures/mass_increase.html#Mass%20Really%20Does%20Increase%20with%20Speed --Khajidha (talk) 04:23, 24 May 2020 (UTC)
 * Also, the speed of light is 186,000 miles per second, not per hour. --Khajidha (talk) 04:24, 24 May 2020 (UTC)
 * 67: I was sort of thinking there's no point of replying since Khajidha had already touched on the issue, but I've decided to make one last go. I think your understanding of mass-energy equivalence or $$E=m\,c^2$$ is likely still seriously flawed. The fact that c or the constant for the speed of light is in the equation does not mean "1% mass is lost at 1% the speed of light% or anything of that sort as I think you may be falsely assuming. I wonder if it's better if you put aside the fact that c is the constant for the speed of light for now as I think it may be causing confusion. If you've read our article and it hasn't helped, maybe try a basic physics text book and look into the subject area so you can better understand why c is in there and what it means (and doesn't mean). Or you could even start with a basic question here, without assumptions based on misunderstandings. Nil Einne (talk) 09:06, 25 May 2020 (UTC)
 * My question is how much mass is lost per how fast it has to travel. Aside from being told now that if mass travels near the speed of light, that mass is gained. 67.175.224.138 (talk) 10:08, 25 May 2020 (UTC).
 * Traveling near the speed of light increases the mass of the object that's traveling, according to the theories. But that has nothing to do with digestion. ←Baseball Bugs What's up, Doc? carrots→ 10:48, 25 May 2020 (UTC)
 * Yep I agree, but my question is not at all about gaining mass of objects, but losing mass to objects. 67.175.224.138 (talk) 11:10, 25 May 2020 (UTC).
 * The speed of light has nothing to do with digestion. Digestion is a series of ordinary chemical reactions. ←Baseball Bugs What's up, Doc? carrots→ 11:15, 25 May 2020 (UTC)
 * But my question is not about the speed of light either. 67.175.224.138 (talk) 11:21, 25 May 2020 (UTC).
 * (EC) What do you mean by "how much mass is lost per how fast it has to travel"? What do you mean by "losing mass to objects". Under what scenarios, and why do you think this will happen? Nil Einne (talk) 11:24, 25 May 2020 (UTC)
 * This was in regards to what you said, mass does not need to travel near the speed of light to be converted to energy. But if it does convert to energy, at what % proportional to the speed of light? 67.175.224.138 (talk) 11:26, 25 May 2020 (UTC).
 * I never said "mass does not need to travel near the speed of light to be converted to energy". From my understanding, saying "mass is converted into energy" can be considered a confusing way of understanding what's going so I took pains to avoid that. Second, did you read what I said about the speed of light? I really think you need to just put aside the speed of light for now. Treat it as a constant in the equation and nothing else. Don't even think about velocities or speeds. Also note that AFAICT, no one said "mass travels near the speed of light, that mass is gained" per se. Instead what was said is "" This is an important distinction as you don't need to travel near the speed of light for what's being described to apply, even if it's mostly irrelevant at low velocities. Anyway I emphasise again you should start with a basic textbook and try your best to put aside what you think you understand since it sounds like it's probably mostly wrong. I no longer think continuing to ask questions here is going to help since IMO you keep seriously misunderstanding what you're being told. Nil Einne (talk) 11:45, 25 May 2020 (UTC)
 * Okay, this was in regards to what you said "The equation, {\displaystyle E=m\,c^{2}}{\displaystyle E=m\,c^{2}} does not mean things need to travel close to the speed of light for energy to be released." But you never explained how slowly that something can be. 67.175.224.138 (talk) 11:48, 25 May 2020 (UTC).
 * As I said "Treat it as a constant in the equation and nothing else. Don't even think about velocities or speeds." Nil Einne (talk) 11:53, 25 May 2020 (UTC)
 * Does that mean, take out the units? Take out the m/s or mph? 67.175.224.138 (talk) 11:55, 25 May 2020 (UTC).
 * No. It means since c is a constant, you just think of it as a constant. What that constant means is irrelevant to you until you have a better understanding of what's going on. You shouldn't be thinking of "slowly" since it's not part of what you should be thinking of, for now. Remember that even when you understand why c is in the equation, it's still a constant. Nil Einne (talk) 12:01, 25 May 2020 (UTC)
 * Well unfortunately that is my definition of a constant, a unitless number. Simply take out the m/s, mph, and such. 67.175.224.138 (talk) 12:07, 25 May 2020 (UTC).
 * And what's never been explained to me about Einstein's equation, is when mass travels towards speed of light, what % of it's mass is converted into energy? Well, I didn't think it would be an arbitrary number like 67%. So I figured 100%. Hence my analogy, on mass losing 1% of its mass to energy, if it traveled 1% the speed of light. 67.175.224.138 (talk) 12:06, 25 May 2020 (UTC).
 * What makes you think traveling at high speed converts some percentage of your mass into energy? ←Baseball Bugs What's up, Doc? carrots→ 12:49, 25 May 2020 (UTC)
 * No it was my question. 67.175.224.138 (talk) 13:04, 25 May 2020 (UTC).
 * You said "when mass travels towards speed of light, what % of it's mass is converted into energy?" So again, I ask, where did you get that idea from? ←Baseball Bugs What's up, Doc? carrots→ 13:30, 25 May 2020 (UTC)
 * Because my understanding is only photons can travel exactly at the speed of light, so mass can only travel a little less than the speed of light. How much less, I wouldn't know. I imagine electrons can still travel faster than protons? 67.175.224.138 (talk) 18:09, 25 May 2020 (UTC).
 * And what does any of that have to do with digestion or any other normal chemical process? ←Baseball Bugs What's up, Doc? carrots→ 19:57, 25 May 2020 (UTC)
 * That the mass of food does not travel fast enough in our body to notably convert into energy. 67.175.224.138 (talk) 21:07, 25 May 2020 (UTC).
 * At this point I'm unsure whether you're ultra-ignorant or whether you're just trolling. ←Baseball Bugs What's up, Doc? carrots→ 21:45, 25 May 2020 (UTC)
 * Dear 67.175, I think you really believe to have asked a meaningful question. But never any physicist said that an object would lose mass accelerating to the speed of light and if you suppose that it must be so because no object with mass can travel at the speed of light well you are desperately mistaken. Actually just the opposite is true: no object with mass can travel at the speed of light because any such object's mass increases while accelerating and would become infinite reaching that velocity. So if an object with mass travels almost at c it must have almost an infinite mass and you would need to give it an infinite quantity of energy to accelerate it to c. Only objects like photons, that from the beginning don't have mass at all can (and necessarily do) accelerate to c.
 * So there is nothing to your idea of loosing mass by accelerating, there is no percent of lost mass relative to speed, and you were also cheating with your claim at the beginning that "if you asked a physics professor, they'll say, more like 0%, because food has to travel towards the speed of light to convert into energy" because no physics professor would ever state such a nonsense. 2003:F5:6F08:8200:3179:F503:CF2E:D769 (talk) 17:22, 28 May 2020 (UTC) Marco PB

How fast are quantum computers when compare to supercomputers?
How fast are quantum computers when compare to supercomputer? Ram nareshji (talk) 19:08, 22 May 2020 (UTC)
 * I don't think that is directly comparable, as they work so incredibly differently and solve incredibly different problems. --OuroborosCobra (talk) 19:27, 22 May 2020 (UTC)
 * Certain problems are hard in the classical model of computation. An example of such a problem is integer factorization. No classical polynomial-time algorithm is known. Modern strong cryptosystems such as RSA are predicated on the assumption that factorization is hard. There is a claim that quantum computers will be able to solve certain problems much faster that are hard in the classical model of computation. Shor's algorithm is a polynomial-time quantum computer algorithm for integer factorization, which should eventually break RSA encryption. The term "quantum supremacy" is used for the situation that a quantum computer solves a problem faster than a classical computer. There has been a claim that quantum supremacy has been achieved, but the validity of that claim is disputed, IMO rightfully so. --Lambiam 07:13, 23 May 2020 (UTC)

User:Lambiam so quantum computers are faster than supercomputer? Ram nareshji (talk) 16:30, 23 May 2020 (UTC)
 * I most definitely did not say that. People who believe in the promise of quantum computing expect that one day quantum computers will beat computers built according to current architectures (which includes supercomputers) for some types of problem (such as factorization). It has currently not yet been proved beyond reasonable doubt that this expectation will ever come true. There are "quantum skeptics" who think the promise will always remain a promise. (The last link may disappear in the future behind a paywall.) --Lambiam 19:28, 23 May 2020 (UTC)