# What is the opposite of FIRE ? **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [November 29, 2009, 9:30pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379 "2009-11-29T21:30:45Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![qbadger](https://avatars.discourse-cdn.com/v4/letter/q/fbc32d/32.png) [@qbadger](https://boards.straightdope.com/u/qbadger)\ **Post date:** [December 3, 2009, 1:03am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/41 "2009-12-03T01:03:55Z")
> [@dropzone](#): > > Yeesh, the four elements are earth, water, fire, and air and, on the [same chart](http://en.wikipedia.org/wiki/File:Four_elements_representation.svg) ANY educated person should know, the opposite of fire is water. > > Doesn’t anybody study science anymore? [Of course](http://en.wikipedia.org/wiki/File:Wuxing.svg)! Hold on, let me see that diagram again … no I think I’m sticking with ‘wood’? argh. ---
**Author:** ![QuestionMark](https://avatars.discourse-cdn.com/v4/letter/q/a6a055/32.png) [@QuestionMark](https://boards.straightdope.com/u/QuestionMark)\ **Post date:** [December 3, 2009, 1:38am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/42 "2009-12-03T01:38:33Z")
> [@Mangetout](#): > > Unfortunately, optimism alone can’t make this work, and nothing else is in your favour. It’s not only optimism, it’s creativity as well. And the possibility to put ideas and knowledge together. What if all the power needed for this factory would be available, and let’s forget about money, could it be possible to cool down the poluted air centrifuge press decompress let something react with something else somewhere in that direction… and blow out clean air and some kind of oil, fluid. Still think it’s do-able. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 3, 2009, 1:59am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/43 "2009-12-03T01:59:41Z")
> [@QuestionMark](#): > > It’s not only optimism, it’s creativity as well. > And the possibility to put ideas and knowledge together. > > What if all the power needed for this factory would be available, > and let’s forget about money, > could it be possible to cool down the poluted air > centrifuge > press decompress > let something react with something else > > somewhere in that direction… > > and blow out clean air > and some kind of oil, fluid. > > Still think it’s do-able. It’s possible to recombine the exhaust products to produce fuel - that has already been covered in this thread, but: -It’s not possible to do it anything like the way you’re describing. -It’s not worth doing. Of course you’ll probably say you still think it’s do-able. You’ll be wrong. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [December 3, 2009, 4:32am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/44 "2009-12-03T04:32:57Z")
> [@QuestionMark](#): > > It’s not only optimism, it’s creativity as well. > And the possibility to put ideas and knowledge together. > > What if all the power needed for this factory would be available, > and let’s forget about money, > could it be possible to cool down the poluted air > centrifuge > press decompress > let something react with something else > > somewhere in that direction… > > and blow out clean air > and some kind of oil, fluid. > > Still think it’s do-able. Touch the back of a running refrigerator or air conditioner. _That’s_ why your idea doesn’t work. ---
**Author:** ![Shmendrik](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shmendrik](https://boards.straightdope.com/u/Shmendrik)\ **Post date:** [December 3, 2009, 6:23am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/45 "2009-12-03T06:23:49Z")
> [@QuestionMark](#): > > It’s not only optimism, it’s creativity as well. > And the possibility to put ideas and knowledge together. > > What if all the power needed for this factory would be available, > and let’s forget about money, > could it be possible to cool down the poluted air > centrifuge > press decompress > let something react with something else > > somewhere in that direction… > > and blow out clean air > and some kind of oil, fluid. > > Still think it’s do-able. Physics: F Engineering: F Poetry: B+ ---
**Author:** ![QuestionMark](https://avatars.discourse-cdn.com/v4/letter/q/a6a055/32.png) [@QuestionMark](https://boards.straightdope.com/u/QuestionMark)\ **Post date:** [December 3, 2009, 8:59am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/46 "2009-12-03T08:59:00Z")
> [@John\_W.Kennedy](#): > > Touch the back of a running refrigerator or air conditioner. > > _That’s_ why your idea doesn’t work. Or is it one of the reasons it just might work?😃 ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 3, 2009, 12:39pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/47 "2009-12-03T12:39:41Z")
> [@QuestionMark](#): > > Or is it one of the reasons it just might work?😃 No. ---
**Author:** ![QuestionMark](https://avatars.discourse-cdn.com/v4/letter/q/a6a055/32.png) [@QuestionMark](https://boards.straightdope.com/u/QuestionMark)\ **Post date:** [December 3, 2009, 1:30pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/48 "2009-12-03T13:30:34Z")
> [@Czarcasm](#): > > No. That’s a Czarcastic “Yes”, no?! Years ago we couldn’t fly, now we drop rockets on planets, for fun, money enough to see if there’s any water, at times we have so much water it makes the sea rise… I think we can reverse the proces. Why not? ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [December 3, 2009, 1:33pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/49 "2009-12-03T13:33:59Z")
> [@QuestionMark](#): > > Something else: > I’m Dutch. I made a website page in English. It should be checked on language. > Can I mention the page here, or not, or maybe in another post? (It’s about stop smoking). My apologies, **QuestionMark** , I hadn’t noticed this before. I suggest that you start a thread in the MPSIMS forum, asking if there’s someone who would want to help you with your website English, and then handle it off-boards. Once your website is up, depending on what it is, we do allow some (limited) self-advertising, so you could announce it then. Stereotyping aside: My experience with most Netherlanders is that their English is excellent, and often better than many native speakers. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 3, 2009, 2:18pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/50 "2009-12-03T14:18:17Z")
> [@QuestionMark](#): > > That’s a Czarcastic “Yes”, no?! > > Years ago we couldn’t fly, > now we drop rockets on planets, for fun, > money enough > to see if there’s any water, > > at times we have so much water > it makes the sea rise… > > I think we can reverse the proces. > Why not? Have you taken any basic science courses in school? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 3, 2009, 4:32pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/51 "2009-12-03T16:32:03Z")
> [@QuestionMark](#): > > What if all the power needed for this factory would be available, > and let’s forget about money, There’s your problem. You can never forget about money and you never have all the power you need available for free. Think about fusion power. We know it’s theoretically possible. We know that we can make it work for a tiny fraction of a second. But for all the billions of dollars poured into it over many decades nobody has been able to power an ordinary house from it. What you’re proposing would require greater input for even less effort, It makes no sense to even try, because we fully understand both halves of the equation, what power goes in and what results come out. There are no results worth the effort. We see this a lot here. People with no real understanding of science propose a process that would essentially be magic and refuse to take the word of lots of people who know science very well that it is impossible in the real world. Their defense is usually the same as yours. Other amazing things have been done: why not mine? The answer is that your amazing idea is unpractical for very good and well understood reasons. Unfortunately, ideas are often undermined by equations. And what works in the laboratory doesn’t necessarily scale up to the mass market. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 3, 2009, 4:36pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/52 "2009-12-03T16:36:20Z")
> [@QuestionMark](#): > > Years ago we couldn’t fly, > now we drop rockets on planets, for fun, This is called argument by analogy. Years ago, X was considered a crazy idea, then technology made it possible, therefore crazy idea Y should also be possible! It’t flawed logic - here’s why: Years ago, heavier than air flight was considered a crazy dream, but now we have aeroplanes. Therefore my crazy dream of growing to be 100 feet tall by eating marbles will also come true! ---
**Author:** ![qbadger](https://avatars.discourse-cdn.com/v4/letter/q/fbc32d/32.png) [@qbadger](https://boards.straightdope.com/u/qbadger)\ **Post date:** [December 3, 2009, 4:37pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/53 "2009-12-03T16:37:02Z")
> [@Czarcasm](#): > > Have you taken any basic science courses in school? I think you meant to say “Are you taking…” All kidding aside, I have a serious question: what is the opposite of ELECTRICITY? and how can we reverse the process? Ok that was two questions. One more: Why not? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [December 3, 2009, 4:45pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/54 "2009-12-03T16:45:09Z")
> [@QuestionMark](#): > > I think we can reverse the proces. > Why not? As others have said, we can reverse the process to some degree, but it will cost more energy put in than you get out. You will always end up adding more heat to the environment then you will take out. Always. The reason is The Laws of Thermodynamics. They are _really_ important. You really need to understand them before going on with this discussion. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [December 3, 2009, 8:07pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/55 "2009-12-03T20:07:34Z")
This guy writes like a poor man’s **rwjefferson**. 😛 ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [December 3, 2009, 8:08pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/56 "2009-12-03T20:08:44Z")
> [@Telemark](#): > > As others have said, we can reverse the process to some degree, but it will cost more energy put in than you get out. You will always end up adding more heat to the environment then you will take out. Always. > > The reason is The Laws of Thermodynamics. They are _really_ important. You really need to understand them before going on with this discussion. You cannot win. You cannot break even. You cannot even stay in the game. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [December 3, 2009, 9:01pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/57 "2009-12-03T21:01:11Z")
**QuestionMark** said: > [@](#): > > I was asking myself “What is the opposite of fire” because I was thinking about an engine, like one in a car, where fire is ‘added’ to make explosions, etc. > If there would be a large scale factory, that would do the opposite of this car-engine, so it would produce oil and clean air, how would the proces work? Somewhere in there, we would have … right? > Something like decompressing and freezing, and “un-mixing”. > Still think it’s do-able. I’m trying to think how to explain this. “Fire” is the release of energy from rapid oxidation. It is, in essence, energy. Like electricity, or heat, or light, it is a form of transfer. Car “explosions” are small exothermic reactions. Exothermic means it releases energy (in the form of heat) - in this case, via fire. The small fires are triggered by a spark (in gasoline engines) because fire takes three things. Fuel, an oxidizer (typically oxygen), and heat. That heat is _activation energy_. Activation energy is energy that must be input to a reaction to make it start. Fire is exothermic, so once the reaction triggers, it releases more heat into the system, which means the reaction tends to proceed without additional input of energy from outside the system - because there is additional energy coming from within the system. That energy is from chemical release from changing complex molecules into simpler ones. So “fire” is not really added to a car engine. A spark is added, which starts the reaction, but the reaction comes from the fuel and the oxygen and runs until the conditions that drive the reaction have changed. This means all the available fuel has been converted and can no longer react. Or that the pressure has changed so the conditions no longer support the reaction. But the key is that fire was a _product_ of the reaction, not an _input_. Now lets talk about your hypothetical factory. The idea is to take products of the previous reaction (base materials like carbon, nitrates, water) and convert them into higher energy states. This kind of reaction is an _endothermic_ reaction - it requires the input of energy in order to occur. These kinds of reactions are self-limiting, because if you take away the input energy, they quickly use up the energy available and stop. Think electrolysis of water into hydrogen and oxygen. H[sub]2[/sub] and O[sub]2[/sub] are higher energy states than H[sub]2[/sub]O, so even though the latter _looks_ more complex, it is less so by the eyes of chemistry. Anyway, for electrolysis to occur, you have to input electricity to the water for the water molecules to break apart and reform as oxygen and hydrogen. The reaction does not produce heat because the heat is absorbed by the reaction. A strong endothermic reaction is used to make portable ice packs - you break the internal packaging and the pack suddenly becomes icy cold so you can treat an injury or such. That reaction is taking in heat from the environment. Back to your factory. You are looking for a reaction that takes in energy in order to work. Well, that energy must be available in the proper form for the reaction to occur, and in the proper amount. Trying to separate water into hydrogen and oxygen using sunlight is going to be a very tiring process. It won’t work. It takes electricity to put the right energy in the right place. For any reaction, similar constraints apply. Here is the thing, whenever you run a chemical reaction, there is energy lost to the system. That is called entropy. Entropy is what drives reactions the direction they go. Entropy is why gasoline burns to form oxygen and carbon dioxide and other stuff, rather carbon dioxide and other stuff burning to form gasoline. So in order to do things like cool a refridgerator or freezer, you have to remove energy from that area. In order to remove the energy, you have to do something with it. Those devices work by moving that energy from inside the box to outside the box. But here is the trick - entropy wants to drive the reaction to keep the inside of the box the same as the outside of the box. In order to remove energy from within the box, we must spend _more_ energy making the process occur. We have to force it, and that force is more energy. So your “anti-car” factory is not going to be reducing the amount of energy in the environment, it is going to be increasing it, because we will be spending more energy to force the reaction than is removed by the reaction. So why does photosynthesis work? It takes in energy from the Sun via sunlight. Sunlight is the “force”. The plant cells use energy in order to transform the carbon dioxide into oxygen and plant food. **QuestionMark** > [@](#): > > What if all the power needed for this factory would be available, > and let’s forget about money, > could it be possible to cool down the poluted air > centrifuge > press decompress > let something react with something else > > somewhere in that direction… > > and blow out clean air > and some kind of oil, fluid. And heat. It will also blow out heat, which is what you are trying to eliminate in the first place. Oops. > [@](#): > > That’s a Czarcastic “Yes”, no?! Just because the poster’s name is **Czarcasm** does not make everything he says sarcastic. **qbadger** said: > [@](#): > > My understanding is that carbon sequestering refers to the net effect of photosynthesis and cellular respiration, i.e. the carbon in trees comes from some of the carbon in the photosynthesis reaction. Yes, using trees for carbon sequestration is just understanding that photosynthesis strips carbon from the carbon dioxide and uses that in tree growth (i.e. tree cells), so the carbon is now part of the tree. So that carbon is no longer free to the environment to make carbon dioxide again. Until the tree dies and decomposes or is burned. That is why oil and natural gas are carbon sequestrations. The original plant matter bound up the carbon, and then the centuries of being buried kept that carbon tied up and unavailable for conversion back to carbon dioxide. Until humans started digging it up and burning it. Some sequestration plans consist of trying to isolate carbon dioxide during production and then pumping it into large underground “vaults” so it cannot escape. These vaults might be salt domes, i.e. large pockets in salt that have been mined and form a hollow underground enclosure not open to the atmosphere. Any sequestration plan must isolate the carbon so it cannot reenter the atmospheric cycle. **qbadger** said: > [@](#): > > All kidding aside, I have a serious question: > what is the opposite of ELECTRICITY? and how can we reverse the process? > > Ok that was two questions. One more: > Why not? Define what you mean by “opposite”. Because one opposite of electricity is magnetism. Electricity and magnetism are linked effects, one causes the other and vice versa. That’s why we call the whole thing “electromagnetism” - it’s a combined whole. How do we reverse what process? Define what you mean by “reverse”. The word has a simple meaning until you realize that the meaning is colored by the topic to which it is applied. What is the reverse of “blue”? What is the reverse of juggling? (Juggling the opposite direction? Putting things back in a proper orientation? Setting things down?) ---
**Author:** ![Silmandil](https://avatars.discourse-cdn.com/v4/letter/s/dbc845/32.png) [@Silmandil](https://boards.straightdope.com/u/Silmandil)\ **Post date:** [December 3, 2009, 9:34pm UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/58 "2009-12-03T21:34:16Z")
> [@Mangetout](#): > > Years ago, heavier than air flight was considered a crazy dream, but now we have aeroplanes. > Therefore my crazy dream of growing to be 100 feet tall by eating marbles will also come true! Marbles eh? I would have expected beans. Lots and lots of beans. ---
**Author:** ![Shmendrik](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shmendrik](https://boards.straightdope.com/u/Shmendrik)\ **Post date:** [December 4, 2009, 2:04am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/59 "2009-12-04T02:04:56Z")
[Paging](http://boards.straightdope.com/sdmb/showthread.php?t=481667) **ivan astikov**. ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [December 4, 2009, 4:39am UTC](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379/60 "2009-12-04T04:39:50Z")
> [@Silmandil](#): > > Marbles eh? I would have expected beans. Lots and lots of beans. You eat beans? First the OP demonstrated his ignorance of basic science, and now you you are showing how little you know about mathematics. 😃 [Previous page](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379.md?page=2) [Next page](https://boards.straightdope.com/t/what-is-the-opposite-of-fire/519379.md?page=4)