This is a bit of a geeky question, but I am sure y’all will forgive me.
I understand that Star Trek is fiction and that much of the technology presented is fanciful and without basis in the physical universe as we understand it. I know that things like “Warp Drive” and “Inertial Dampeners” are nothing more than words and that today’s physicists can no more create an “inverted tachyon bean” than they can travel through time.
Nontheless, it seems that quite a bit of the coolest technology you see on the show is based on a simple concept. Humankind has, for a long time, understood how to convert matter to energy. Every time I strike a match, I begin a process which converts the matter making up the matchstick into light, heat and other forms of energy.
What we don’t know how to do is reverse the process, converting energy into matter. Right?
On Star Trek, quite a bit of technology seems to be based on this ability. Food replicators, holo-technology and transporters, just to name a few, would probably be easy to invent, provided science discovered a way to convert stored energy into matter. Once you can do that, the only remaining hurdle is the type of matter - and that’s just fine tuning.
So, what about it, physics crowd? Are we close? Is it even (theoretically) possible? Am I missing something?
Interesting question although I think you are wrong on your characterization of a match being a covnersion of mass into energy. A match lighting is a chemical reaction. You are converting one substance into another and the conversion is exothermic.
Actually, as I think about it more, I wonder if at least a little mass isn’t being converted? The energy released in a match has to account for some mass since, presumably, you could convert the energy back. Now I’m confusing myself…
So, if that is the case, then your basic plant is an energy to mass converter. It takes energy from the sun and does a ‘reverse match’ process that uses energy to create more complex molecules. When we burn a tree we are breaking those molecules apart and getting the heat back. Aren’t we?
I give up…I think I’m missing something here but I don’t know what. I am only posting it to see if it helps prompt other responses (ignorance on this board attracts Doper’s like a moth to a flame).
the apparent los off matter when you burn stuff is just because some of the resulting matter is no longer solid (usually CO[sub]2[/sub], but none of it is actually destroyed and turned into energy.
Let’s start with some of the misconceptions here. When a match is lit it is not a conversion of mass into energy! It is a chemical reaction consisting of breaking up certain molecular bonds and forming others, which result in a slightly lower total energy. The rest of the energy is released as heat.
That reaction can be reversed! (It’s a bit tricky to create a match from smoke, but in theory it is possible to create hydrocarbons and oxygen from carbon dioxide and water)
You are talking about nuclear reactions. The energy content of matter according to the famous e=mc[sup]2[/sup] corresponds to about 10[sup]15[/sup]joules per gram! That’s a lot!
Now, keeping that in mind, creating mass from energy isn’t that difficult. At CERN and similiar places it is done as a matter of routine, but in minute amounts. (I believe that they managed to create something like 14 molecules of anti-hydrogen, just to put things in proportion)
—8<—
In preview I see that I’ve already been beaten, but I believe that my discourse adds something to the discussion to I’ll post it anyway.
My tenuous grasp of physics tells me its possible, but has a huge problem assosciated with it in the amount of energy required.
First off, sdimbert, a burning matchstick doesn’t convert matter to energy in the truest since, it converts complex molecules into simpler ones. The mass that is “lost” is given off as exhaust gasses and literally floats away. Next, Whack-A-Mole, plants don’t convert energy to mass - they do the opposite of the match. Using the sun’s energy, they take gasses and convert them to more complex carbon molecules which are solids.
We have been able to conver matter to energy, it’s called nuclear technology. The tiny amount of mass lost in a nuclear bomb gives off quite a big boom. (E=mc[sup]2[/sup]). The converse of this is theoretically possible, but it would require an ungodly amount of energy to synthesize even a few ounces of matter. Somebody else can do the math.
In preview, I see that I was also beaten to the punch and much of what I have written has already been said. I’ll post anyway and pretend I said something new.
Yes, a burning matchstick does convert mass to energy, and plants convert energy to mass. Since c is so large (in units used by us mere mortals), when you divide the energy released in burning by c[sup]2[/sup], the change in mass is much too small to measure. But the energy does come from a change in mass. The complex molecules’ mass is less than the sum of masses of the simpler molecules that make them up. The difference in mass times c[sup]2[/sup] is the amount of energy released
Not exactly, the release of energy changes the mass. Similarly, in the case of nuclear reaction the energy released comes from breaking and reordering of nuclear bonds* and the release of energy changes the mass. The only difference is the magnitude.
However, there is no such thing as conversion of mass to energy. The mass change is the consequence of the energy release, not the cause.
Again, we do not convert mass to energy. We run processes in which systems are changed from one stable configuration to another and if the new stable configuration is a lower energy state, energy is released, and a local mass deficit is realized.
On the contrary, there is a matter-to-energy conversion going on here. However, the amount of energy produced in a chemical reaction is so miniscule that there is no measurable mass difference between the products [including gases, such as CO[sub]2[/sub](g) and H[sub]2[/sub]O*(g)] and the reactants [including O[sub]2[/sub](g)*].
Including all reactants and all products was an important advance in the late 18th and early 19th centuries, and led to the “Law of Conservation of Mass.” This law is now stated as “No detectable gain or loss of mass occurs in chemical reactions.”
With nuclear reactions there is a detectable change in mass between the products and reactants. More generally, the actual mass of an atomic nucleus is always slightly smaller than the sum of the rest masses of all its protons and neutrons. The mass difference represents mass that is changed into energy as the protons and neutrons bonded together to form the nucleus, this energy being released from the system. This energy is called the binding energy of the nucleus.
What does this have to do with chemical reactions? What many do not realize is the same thing is going on with chemical reactions. In an exothermic reaction, the mass of the products actually is slightly less than those of the reactants. However, it is not measurable. For example, if I combust 1.000 g of H[sub]2[/sub](g) with 7.937 g of O[sub]2[/sub](g) to form 8.937 g of H[sub]2[/sub]O*(l)*, 141.8 kJ of energy is evolved in the form of heat. This corresponds to a mass difference of 1.58 x 10[sup]-12[/sup] grams. This mass difference is not measureable, but still exists. You just need to add 9 more decimal places to my mass numbers above to see it!
(On preview, I see that DrMatrix has beaten me to the punch. But I went to all this trouble, so I’m posting anyway!)
No, the misconception is that there is such thing as conversion between energy and mass. You don’t convert one into another - the two are equivalent. When you, say, burn hydrogen and oxygen to form water, the resulting water is lighter than the hydrogen+oxygen used, because the heat ( = energy = mass) radiates away.
Anyway, as for food replicators - theoretically possible, but I can’t even imagine how one would go about it, let alone start designing one. Also remember that to make 1kg of food, you need to power the replicator with 0.5kg of antimatter which reacts with 0.5kg of normal matter, and if you have 100% efficiency, produce enough energy to create 1kg of matter. I think I’ll stick to cooking.
If I’m reading all the threads correctly I’d say that mass --> energy conversion and energy --> mass conversion happen all the time all around us. In the growing of a plant or in the burning of that plant. Still, the mass created or lost is very very small so it’s not likely to help you much.
In order to be of help you want your food replicators. On a macro scale (macro in this case meaning observable by a human unaided) the energy requirements would be stupendous. tc wrote that there is approximately 10[sup]15[/sup] joules of energy in 1 gram of matter. I saw a show somewhere that said 1 gram of antimatter (and 1 gram of matter to go with it) is sufficient to orbit the space shuttle.
So, assuming robby can build your food replicator, your basic McDonalds Value Meal will cost you several hundred million dollars (gove or take) in energy (and that is not including robby’s grant money or construction costs).
As an aside the same show that mentioned how much antimatter it takes to orbit the space shuttle said, IIRC, that a nuke achieves a 3-5% mass --> energy conversion. Antimatter would net you 100% in comparison which is why so little would go such a long way. The only problem is I also heard that if you made 1,000 accelerators to make antimatter with today’s technology it would take more than a century (or millenia?) to create 1 gram of antimatter so we won’t be seeing this anytime soon.
Actually, if you’re talking about “system” mass you don’t even have to include the word “detectable,” because system mass is absolutely conserved. A system consisting of two photons (each of zero mass) that have equal but opposite momentum has mass.
m[sup]2[/sup] = E[sup]2[/sup] - p[sup]2[/sup]
c = 1
m = mass
E = energy
p = momentum
So if p = 0 then m = E
(I see scr4 beat me to it but I’m posting it anyway.)
I’m assuming these theoretical beans would be what the replicators make. They would have the property of making the eater flatulent before they are eaten. Surely there should be something in the Prime Directive against such backward foodstuffs.
Let’s not rule out replicators yet, though. If the input is just energy piped in on a couple of wires, it’s totally impractical. But what if the input is a bunch of carbon, hydrogen, oxygen, and assorted other elements? The replicator could then just re-arrange the atoms into something that resembles bacon and eggs, or caviar, or whatever. It’s still beyond our current technology, of course, but it’s not totally laughable for some time in the future.
Neal Stephenson’s “Diamond Age” included some replicators which might be more near-term achievable than an energy->mass device. His description was essentially a vending machine using a scheme like that suggested by Chronos. Raw materials were provided to the device and assembled by nano-scale machines.
While I preferred “Snow Crash” for a good read, “Diamond Age” should be must-read material for anyone interested in nano-machines. Stephenson has some very interesting ideas and tells a pretty good story along the way.
What about the transmutation of matter? If that is the term, from one element to another. I once read somewhere that a nuclear reactor can in very small amounts take one element and transmute it to another. Lead into gold???
I may be entirely wrong as I’m not up on the Star Trek details, but I had the vague impression that their replicators worked on the ‘chemical recomposition’ principle as well. I thought that there was some mention on Voyager that they lacked whatever element packets (diamonds & water, plus other traces?) to properly produce their food.
A proper cup of tea, however, might be difficult to replicate.
