# What is the best way to use my two portals?

To avoid being too broad, I'd like to use the portals for purely altruistic purposes (health, environment, safety), and not for scientific or military acheivement (e.g. - not an instant space elevator, which would be to save money and a bit of the 'ol environment).

My fairly well-to-do scientist is today working in the lab, when an alien race delivered two 3m radii portals: A connects to B. Place a person or object through A and they come out of B. It is an amazing thing for her to be given. They only weigh about 10kg too, so they can be handled more easily than a fictional 'stargate'.

The aliens have said rather condescendingly that humans won't be able to deconstruct it to make more of them, but more positively that it could only be used if she, herself, completely supported its use.

She has made her living, ready for a peaceful retirement in Portland's west hills, so she doesn't need money. She wants to use it for an altruistic purpose, which would only include increasing the health, safety, or environment. It requires no energy input that we know of, and can presumably last for a very long time and be transported easily. Technology is today (plus two new toys).

PS - this is for a short story.

EDIT1: This is an attempt, as stated: to formulate the best altruistic use of this alien gift today would be used for side part of a short story. I have used the dialogue and comments on this question for guidance to avoid being too broad or too opinion-based; although they are very different devices and intentions haha.

• Is travel between the portals instantaneous? – HDE 226868 Jan 2 '16 at 22:54
• @HDE226868 Instantaneous. I seem to recall a short (very good) horror story about a similar thing that was not instantaneous, but this is not the case here. THANKS! for the edit, btw. – Mikey Jan 2 '16 at 23:13
• What happens when you stick the top half of portal A through portal B? – TheNumberOne Jan 4 '16 at 17:30
• @TheNumberOne Exactly the first experiment that popped into my mind. It's not a good answer to the question because it risks destruction of the portal system (and who knows what else in the vicinity?), but then again the possible rewards of attempting to put the orange portal through the blue one are literally unimaginable. – Todd Wilcox Jan 4 '16 at 17:59
• @ToddWilcox In Portal, the portals are always attached to a surface. Personally, the first experiment that came to my mind is what happens if you attempt to put something in through the back-side. – DoubleDouble Jan 4 '16 at 21:50

# Congratulations! You've solved the energy crisis!

Place Portal B some distance above Portal A. Now place a turbine blade in between the two of them. Slowly insert a steady stream of water, stopping when you reach a certain amount.

As the water travels through Portal A, it goes to Portal B. It then turns the blade of the turbine (producing electricity), and goes back through Portal A. It's a perpetual motion machine.

Why this works

The portals take an object at a lower potential and move it to a higher potential. Thus, the object is given a higher potential energy. That energy can then be harnessed.

A problem . . . and a solution

Admittedly, you've got an opening of less than 30 square feet, which is tiny, but you should still be able to generate a substantial amount of energy from this. Simply move the portals further apart (i.e. move Portal B higher) and you've increased the energy change, thus making it possible to capture more energy. You can insert more turbine blades.

It turns out that this thing generates a lot of energy really quickly. See Cort Ammon's answer.

• @Mikey It's no different; it's simply that you can get an unlimited source of energy. Waterfalls are limited to a certain flow rate; you can increase this one as much as you want. I really just used it as an example to show that you can create a perpetual motion machine from the portals, and harness unlimited energy. – HDE 226868 Jan 2 '16 at 23:17
• I think the point here is that, unless your portals do a lot of things to protect themselves (things Portal's portals didn't do), you can break all sorts of conservation laws with them, like conservation of energy (also conservation of momentum, speed of light limits for information, plus probably half a dozen others). At some point this becomes a God device because it can do something nothing else in the entire known universe can do. Your short story could devolve rather quickly, because there's few things it could do more for humanity than breaking the laws of physics for us. – Cort Ammon Jan 2 '16 at 23:23
• I'm trying to do the math, but I think 28m3 per second is a lot, but not enough to provide a lot of energy to the world. Would its peak speed be limited by the friction of falling through air/space? PS- I do not know the physics, so please excuse my ignorance. – Mikey Jan 2 '16 at 23:23
• @Mikey There are limits, but they are exactly the kind of limits engineers have been bending since the dawn of the steam engine. Vacuum tubes with uranium slugs with some ferrite core dropped through coils of wire. Things like that. Then, when nobody is looking, I make the tube longer, so I can wrap more wire and avoid heat issues and get more joules of free energy per second because the height I'm dropping them from goes up. – Cort Ammon Jan 2 '16 at 23:28
• @CortAmmon I'm actually seriously concerned with the turbine blades, now that I think about it. I'm not well versed in structural stuff, so, they might take a hell of a beating after a short amount of time. I, too, am curious about your results. – HDE 226868 Jan 2 '16 at 23:31

This is a follow on to HDE's answer, exploring just how much energy you can get out of the thing. The 3m radius yields roughly a 30m^2 area to drop things through. Do the Portal thing: put one portal above the other, and start dropping!

Now let's consider dropping slugs of material through this thing and seeing how much energy we can develop in them. From our physics classes, we can get a potential energy calculation from the mass of the object, the gravity, and the height of the object. $E=mgh$. Each object that goes through and falls to the bottom, which is some $\Delta h$ below. Now we're going to be interested in power in the end, which is energy per unit time. We're shoving mass through at a rate, $\dot{m}$ (the dot is a fancy way to say a mass rate per time). Putting all of these together, we get the formula $P=\dot{m}g\Delta h$. Power is equal to the mass flow rate times the acceleration of gravity, times the height between the portals.

Now we need to bring in the velocity of the mass. If we're throwing slugs at this system, the faster the slugs are traveling, the more of them we see passing through the portal. Let's simplify and assume we can just continuously throw slugs of material through the portal, that happen to consume the whole area. This means the mass flow rate is proportional to: the density of the material, the area of the portal, and the velocity. $\dot{m} = av\rho$, where $a$ is the area, $v$ is the velocity, and $\rho$ is the density. We know the area (its roughly $30m^2$). Lets throw something really dense through: Uranium ($\rho=19050 kg/m^3$). Put these together and we find $\dot{m}= 571500v (kg/s)$

Now we put all of this together, to get $P=571500v\cdot9.8\cdot\Delta h = 5600700v\Delta h (W)$ Note that I took care of all the ugly unit conversions for us. We have Watts. Of course, we're talking about powering nations, which is typically phrased in larger units, like terawatts. Let's convert to a bigger unit. Megawatt's happens to be a convenient unit, so I'll pick up that for all calculations here on out: $P=5.600700v\Delta h (MW)$

The power consumption of the entire world is 16 terrawatts, thanks to my favorite set of Wikipedia pages of all time. To put that in similar units, 16 TW is equal to 16,000,000MW. That's the number we're going to try to hit with these portals.

Now, if we drop these slugs in a vacuum tube (which is fair game, given we're talking about powering the entire world), we can go arbitrarially fast. But let's be nice and not do that. Let's take the orbital velocity of Earth at LEO: 7.8km/s, or 7800m/s. Solving for $\Delta h$ we get $\Delta h=366 (m)$

Think about what that means. If we built a vacuum tube 400 meters high, at the level of vacuum equivalent to low earth orbit (which we do on a regular basis for testing), put our portals at the top and bottom, and started putting uranium pellets in, we could generate as much power as the entire power consumption of the world.

Now, realistically speaking, that's a high power density. If we pulled power out of this using magnetics, just like a modern generator does, we'd actually have to worry about how to get all of the heat away from the magentic coils. There might be some games to play with superconduction, but I'll leave that for later. Engineers are good at solving heating issues. At worst, you can always do something like drop things from a taller height, and have them moving at a lower velocity. That would let you physically space the coils out along a larger vertical length.

Note, this also shows just how mindblowingly fast things are in space! LEO velocities are fast!

• @HDE226868 Wow. Can you check my numbers? I have company coming over, so can't give them the usual attention. That added up way faster than I expected it to! – Cort Ammon Jan 3 '16 at 0:03
• @Mikey you're being told that your device can create nearly limitless power. If you want money today that's trivial, Investors, Grants and Loans will be at your beck and call. Instead of thinking 'how can this device help the world' you now need to be thinking 'with \$5Tn a year of revenue, and very little costs, how can I best help the world?' – NPSF3000 Jan 3 '16 at 3:26
• @Mikey we don't have 'unlimited energy' right now. Sun, wind and water are difficult and expensive to capture - as opposed to this single rather trivial device that can be ramped up to astronomical proportions (literally). The reason energy is so valuable is because it's a fundamental building block! Look around your room, all you see is energy (in its many forms, including matter) and information (how that energy is organised). If you can access unlimited energy, then you're only limited by information! It trivialises much of life. – NPSF3000 Jan 3 '16 at 3:49
• If you have that at a latitude of 32 degrees And operate it such that it produces 16 TW for one year, you'll produce a net dV in the Z direction (out the North Pole) of 12.86m/s. If you assume a 1% growth in our energy usage and assume this keeps up to that growth rate, it'll cause a 133.3m/s dV over the course of 10 years. This isn't particularly significant, but it's worth mentioning. – iAdjunct Jan 3 '16 at 16:34
• @iAdjunct **grins** I didn't explore momentum much, just energy, but you are right. You'd have to move it around every now and then if you wanted to keep the planet on its current orbit. Such is the price of breaking the laws of physics =) – Cort Ammon Jan 3 '16 at 16:36

## International Rescue/Superhero!

This one requires some charitable donations, but I'm sure the UN could help out here. At the same time you will need to jeep check on your ego in case it gets too large so a degree of anonymity may be required (probably not a suit where you look like a bat or spandex based however).

You have pretty much the ultimate logisitical tool. Instantly able to transport matter from point a, to point b. Anywhere.

You start off by announcing to the world at a press conference you have this technology and this is how you prepare to use it, so everyone knows about it, and makes it harder for anyone else to try steal it or coerce you into a different train of action. Include a demonstration plus details of your charitable donation and how people/organisations/business can help.

Next. Portal transport, using your stockpile of charitable donations you buy yourselfs a quick and handy transport option. Something like a transport place which can take a helicopter and/or you can skydive out of (face it you're going to want to make an entrace where you can!). (Somewhat like Thunderbird 2 I suppose.)

Second thing. Hire a team to monitor the world (space station optional), they keep track of all news stories around the globe allowing you to respond.

Third thing. Base of operations, you'll probably want to stockpile resources for distribution and a place to service and fuel your transport.

Finally save the world!

• Drought in Africa. Fly one portal under the Niagra falls, the other to Africa, water quickly appears, use it to top up a reservoir (somewhat ambitious) or attach to the back of your transport vessel and water the ground below.

• Volcano in the pacific. Use it to evacuate people away from the danger, where they instantly walk from the impending lava straight into a camp with fresh linen and running water.

• Food crisis in Sweden. You set up one portal at your base of operations (or place managing aid), and the other where the food crisis is. Instant delivery of supplies without the logistical worry (think how long it takes to load and send a plane, plus logisitcal cost of crew, fuel, maintenence etc).

• Disease outbreak in Australia. Why worry about multiple plane/ship journeys taking people and medical supplies when you can just send them through the portal.

• Miners stuck down a deep mine in Greenland. Ok you still have the trouble of getting down there and back yourself, but whats one trip compared to multiple especially if theres a lack of supplies.

There are so many endless possibilities of how you could save the world, cutting down on cost and environmental impact (your own plane journey compared to multiple hercules). You're not being paid for it, rely on charitable donations and will try to help anyone anywhere wherever you can, however the multiple inspiring real world heroes you hear on the news become one (hence keeping your ego in check).

And I leave you with this. Where there's heroes. There's always villians. People will try obtain this technology from you for their own evil gains.

• "People will try obtain this technology from you for their own evil gains." ...or to copy it. Once it's widely known that something is possible, it's always surprising how quickly other people come out with their own versions of it, even if they don't have their own copy to reverse-engineer. – Mason Wheeler Jan 4 '16 at 16:04
• It's trickier than you make it sound, really. Don't forget that different places on Earth have different atmospheric pressures, for example. If you want to avoid massive atmospheric issues, you'll want to enclose both ends of the portal to maintain the same pressure on both sides. This severely limits the amount of material you can pass through - it would still be very useful for some cases, but it's far from the perfect logistics device you imagine :) – Luaan Jan 4 '16 at 16:34
• @Luaan Gigantic flatpack airlock! to maintain the pressure of the other portal (as surely if you can match the pressure on the other side within the airlock, you will only require it on one side!). Plus added benefit Submarine rescue! – Crazy Dino Jan 4 '16 at 16:45
• @CrazyDino I'm not entirely sure, but somehow I think the submarine wouldn't quite appreciate the sudden drop in ambient pressure. I mean, a submarine ain't some silly human body (Byphord Dolphin incident, if you dare), but it probably isn't going to end well. – Luaan Jan 4 '16 at 16:57

You shouldn't really discount that "instant space elevator" thing - it's a major thing on our step to a higher level as a civilisation.

Suddenly, a lot of things become almost trivial in cost - solar satellites in Earth orbit, for example, are much more efficient than ground-level solar panels. With "free" orbital insertion, the satellites themselves would be extremely cheap, probably being able to compete with ground-based power generation handily. A lot of the complications with the technology disappear - it'd still take time to exploit fully (e.g. transmitting the power - we know how to do it with microwaves, but it'd still take a lot of engineering to perfect), but it's got a much better potential than anything we can do now, economically.

So now you have solar satellites beaming power down to any place on Earth. Suddenly, you have great opportunities of using that energy - the amount of useable land greatly increases, you can provide cheap fresh water to everyone on the planet, and you can get rid of lots of those ugly coal-powered power plants. And since your energy costs have dropped so low, you could even possibly move on to making petrol from thin air, solving both a potential energy crisis and closing the carbon cycle with one swing. Again, it'd still take a long time to develop, but if energy prices drop low enough, it's going to become a thing.

Not ambitious enough? Why stop at Earth's orbit? Move one end of the portal to the asteroid belt or Jupiter, and use it to build up mining infrastructure. Once you get the (robo-)colonies going, they can use mass drivers to send materials back to Earth. This is going to have some trouble competing with Earth-based installations for some time, but it should become very profitable relatively soon, increasing the living standards all over the world. And of course, it would give us an opportunity to disperse over the Solar system at least - in a hundred years or two, the next Planet Killer that hits Earth might not mean the death of our whole species anymore.

Don't want to send your only portal on such a long journey? You can still save yourself a huge amount of work if you use the portals in Earth orbit to accelerate interplanetary spaceships - allowing them to save up quite a bit on fuel needs for the trip (you only need to keep enough fuel to accelerate in your destination - that's to the brutal rocket equation and various engineering hurdles, this means saving much more than half the cost).

All in all, your portals are a bit too much of a god device for a good story, I think. Unless of course you focus the crux of the story on some issue the portals can't fix, or some issues caused by the portal :P

A great example might be some of the suggestions here and in the other answers - look at a suggestion and think hard (or, in some cases, just thinking at all is quite enough) about what could go wrong. Used the portal to transport water to water-starved regions? Ooops, we accidentally opened a line between two places with vastly different atmospheric pressures and compositions. Used it to generate infinite power? Ooops, the portals got a bit misaligned and the near-the-speed-of-light pellets got out of the loop (although be very careful about that - I have a feeling it might be a planet killer :)).

Or you can just look at all those social changes that come from your little device - the story can very easily be about a factory worker who lost job one day due to that sodding piece of stupid technology replacing him!

• Problem is, you don't actually have free orbital insertion of satellites. The difficult part about putting something into orbit isn't getting it up there (which is what a portal could help with); that's actually surprisingly easy. The thing that takes a huge amount of energy is getting it up to orbital velocity so that it stays up there instead of falling straight back down to earth. Randall Munroe explains it very well here. And remember how portals conserve relative velocity: speedy thing goes in, speedy thing comes out. – Mason Wheeler Jan 4 '16 at 22:18
• @MasonWheeler I'm well aware of that fact, but you're constraining yourself within the realm of reality. The portal explicitly breaks conservation of momentum - the actual momentum of the object exiting the portal will be its original momentum relative to portal A + momentum of portal B. Note how all the other answers rely on the very same thing, whether they deal with orbital velocities or not (hint: Earth rotates rather fast). Whether "speedy thing goes in, speedy things comes out" means conservation of momentum or not is irrelevant, since the OP isn't basing his portals on Portal :) – Luaan Jan 4 '16 at 23:05

## Contratulations! You saved our Universe!

If a portal is always able to transport matter, once one of them reaches a vacuum (e.g. outer space), matter will move towards that vacuum, creating a similar effect to what is known about black holes.

Besides the obvious destruction power one could harness from transporting only one portal to outer space, this effect would be extremely useful for closing existing black holes: by releasing each portal from opposite directions into a black hole's gravity pull, when both portals superimpose, that same black hole would pull itself into extinction.

This allow us to close the universe by extinguishing all gravitational singularities, thus guaranteeing that the Big Crunch will never happen.

Answering the question, humans granting immortality to our universe would perhaps be the most universal "altruistic purpose".

• This is a really cool idea. However, because of the time dilation near a black hole's event horizon, an external observer will have to wait infinitely long for the portals to superimpose. – Mihai Jan 5 '16 at 0:31
• @Mihai I am assuming that all the freely-falling particles whose motion cannot be determined beyond a finite time would be constricted to the space between the two approaching portals, i.e. time dilation would happen only between them. – Armfoot Jan 5 '16 at 11:08

Use the 2 portals to control the distribution of water. This could be useful in several ways:

1. When an area of the world is undergoing drought, bring in water from another place to fill up local dams, rivers, or other water storage systems.
2. When an area of the world is undergoing flooding, take out water to another place that can handle the additional water. Bonus if this and #1 could be done at the same time.
3. When global warming raises the global water levels, move water from the earth's ocean to some other place where it won't cause problems - maybe outer space or the moon.
• The danger of global warming isn't really (just) rising sea levels (although it's certainly troublesome), but many of the additional effects. The oceans tend to act as a damper on weather and temperature effects, so I'm not sure removing it would be such a great idea. Now, temporarily shifting it to space to freeze it and add to the polar ice caps might help lower the planet's temperature, although I'm not sure this could be done practically (given the size of portals, and the sheer amount of water required...). – Clockwork-Muse Jan 3 '16 at 7:46
• @Alan M - It's a fine idea, but may require tweaking, to keep it from destroying ecosystems (different pH balance, biota, water qualities, etc.). For number 3, the math suggests I won't be able to move such vast amounts of water at the rate in which it would be required to make any difference. – Mikey Jan 3 '16 at 20:30
• @Clockwork-Muse: Space wouldn't be all that good at freezing ice. People think space is cold, but that's not really true; it's more like "what temperature are things in space?" is essentially meaningless in the sense that we generally think of temperature, because there's so little matter there. In fact, one of the serious problems spacecraft face is staying cool, rather than staying warm; it's hard to dump waste heat with no atmosphere to conduct it away! Water set out in space would actually be more likely to boil than freeze, due to the way pressure and temperature interact. – Mason Wheeler Jan 4 '16 at 22:22
• @MasonWheeler - You're right, I forgot about the boiling. However, I knew you couldn't just stick it "in space" - at minimum you'd need it to be in the shadow of something (earth would be handy, but would require a lagrange). Given the necessary time to remove the water, it may start recondensing by that point.... or perhaps we should just send it to mars! – Clockwork-Muse Jan 5 '16 at 1:52

It may be tempting to use this for "unlimited energy" but this is wildly impractical. Transmitting power is difficult because there are always losses (either losses in the transmission line or in the storage for physical transport). It would only be feasible for nearby uses but definitely not even the entire US, let alone the world.

Because these have to be physically moved and they cannot fit through themselves, they have limited practicality for things on a world scale except for hotspots or for scientific advancement.

The two biggest uses I can see are (1) military transport to war zones and (2) getting into orbit.

The former is still somewhat limited in its usefulness, especially with the probability of it falling into enemy hands.

The latter is significant, especially since it would become trivial to construct a larger space station, which would significantly improve both scientific research and microgravity-based medicine. It would also make intercontinental travel easier, at least from a single location, as you can construct recently vehicles in orbit, load them, then drop them off.

This, IMHO, would be single most important use of this technology in the world because it can directly help the entire world practically.

If, however, you must refrain from military and scientific purposes, there are some other alternatives, most notably in the form of transportation.

There are some extraordinarily expensive medicinal machines and it would be great if we didn't have to build so many. If two hospitals were linked (say one in central US and one in London), they could share resources between entire continents so each hospital only needs half the equipment it would ordinarily need. They would also have faster transportation to hospitals near the other hospital, further decreasing equipment requirements. This may be one of the more significant uses of a point-to-point static link.

Math behind transmission line losses:

To show you the kinds of things I'm talking about with transmitting that energy, let's say you have this awesome generator in New York City and wish to replace the Palo Verde Nuclear Generating Station in Arizona. Yes, this is a contrived example because you'd realistically put the generator in a better location, but this is just looking at a single replacement of a single generator; doing this on a nationwide or worldwide scale would be enormous, so let's just look at one transmission line.

If your cables were as thick as the cable bundles on the Golden Gate Bridge but were solid copper and your transmission line was at 765kV (the highest I could find), your cable incurs 4.675MW of losses, which is small compared to the 3937MW generated by the station you are replacing. If the cables were half that thick, it would waste 18.7MW, which is still small. If you somehow had a dialetric that could handle 2000kV lines, your losses are 0.683998MW and 2.736MW respectively, both manageable.

Except that your small cable (2.031e10kg) just consumed more than the 2014 worldwide production of copper (1.87e10kg). Congratulations. If you think drilling for oil is hurting the environment, just wait until you have to produce that much copper.

Sure, this line could be thinner because it can handle the losses (basically trading wastefulness in mining with wastefulness in heat generation) but this is just ONE line. A number I found shows that the US, in 2011, had an overall summer production of 1000GW of power - three orders of magnitude higher. Incidentally, if half of that were transmitted by the thicker line (and at least half will have to in the US), your line losses are 11GW and it weighs 8.122e10kg.

Ok, so we get this from other planets... Except that the space shuttle with its boosters at launch weighed 1.99e6kg and that was HUGE. We don't have the ability to support an extraterrestrial mining operation, let along get all that copper back here. So that's right out.

And this was just for the US.

You could theoretically instead use this to power a plant to store energy by either generating hydrogen from the oceans or creating hydrocarbons, but these produce a lot of heat in the re-generation of electrical energy later, not to mention the volatility of hydrogen or the gaseous emissions of the hydrocarbons.

You could absolutely use this for free energy, but the bottom line is using the energy would be significantly more destructive than keeping our distributed power supply system.

• Ah, but @iAdjunct, I have specified, "and not for scientific or military acheivement (e.g. - not an instant space elevator, which would be to save money and a bit of the 'ol environment)" because this is elsewhere addressed in the short story. Although I agree that unlimited energy is a bit impractical in today's technology. – Mikey Jan 3 '16 at 3:00
• I understand that you said that, but you seemed to dismiss it because it was the obvious choice and you wanted to use it for altruistic purposes. The portal can do lots of things, but nothing as altruistic or enormously advantageous as going to space. – iAdjunct Jan 3 '16 at 3:04
• @NPSF3000 yes we do, from the nearest power planet. We don't transmit North America's energy usage from Europe - we transmit it from many distributed power plants. Transmitting the entirety of North America's energy from another continent (or vice verse) would be wildly impractical (and possibly impossible). – iAdjunct Jan 3 '16 at 3:44
• @NPSF3000 - if you will get off your soapbox for a second and figure out what is meant, you'll see that the free energy you will produce from the converted infinite potential kinetic energy is electrical energy (or more potential energy), not chemical energy (which is what oil is). In order to transfer electric energy, you need huge conductors or you need to store it chemically. If we were good at storing electricity chemically, solar panels and electric cars would actually be efficient, but we are pretty terrible at storing electrical energy chemically (which is why we drill for it). – iAdjunct Jan 3 '16 at 3:59
• Transmission losses matter because energy is limited and expensive. If you have energy that is nearly free and unlimited, then a global transmission system that gets 1% efficiency and 99% losses is not impractical, you can use that. – Peteris Jan 3 '16 at 10:42

It could be a good tool for disposing of hazardous materials. The destination portal could be someplace extremely safe, secure, or distant, and presumably you could go about with the entry portal scooping up radioactive waste or whatever, without having to transport it through places where you don't want to risk spills and take great effort to avoid them.

It might be worth experimenting to discover what this exactly means: "it could only be used if she, herself, completely supported its use." How is the support detected, and what happens if her support isn't completely there? Like, it doesn't somehow strip people of disease as they walk through, if she thinks how she'd like the subject to be able to walk through, but "doesn't completely support" his plague virus going with him". If it does work that way, then it could function as a magic disease-curing device, for example. Maybe you could get the garbage out of a dolphin's stomach by having it swim through.

You could also see if the aliens have some other good altruistic advice to give us, and use the portal as a demonstration that these guys might have some good info we should pay attention to. After all, humans are pretty backwards and argue with each other a lot, and might benefit from being told some stuff by a third party with demonstrated intelligence.

These portals are time bombs. It only takes one idiot to wonder "What would happen if..." to put the portals in a position to drastically reshape life on Earth, and not in a good way. Transporting people and objects is great, but the laws of physics broken by these portals can have terrible outcomes.

The best thing to do with these portals is to destroy them, if possible; otherwise, return them to the aliens. This is humanity we're talking about. As a species, we're still in the "licking electrical devices to see if they're still on" phase, and only managed to arrive there by licking other things first. We're just not ready for physics-breaking devices.

## Power Generation

Since you only have the single set of portals, you can only create power in one location. That means that a percentage of all power transmitted will be lost due to resistance in the transmitting wires. While today's wires already lose power over distance, there are a few reasons why the portal generator is much, much worse:

• Resources! The power transmission lines would need to be huge to limit power loss, and enormous ultra-high-voltage transmission lines would need to be built, connecting every major, minor, and otherwise-insignificant city to the main power trunk, as well as redundant connections and some serious power network monitoring and switching. Need for new copper, steel, rubber, and other raw materials would skyrocket. The free energy would make it worth it (at least in that regard), but only after significant investment. Maintenance to the power lines may actually be more expensive than building power plants.
• Physical limits! Power loss is equal to the square of the current times the resistance of the wire (which is, in turn, based on the diameter of the wire). While raising the voltage has a significant impact, it can only be raised to around 2000kV. At that point, power is lost to the air through corona discharge. Larger wires help, but again, there are a physical limits - eventually, the world runs out of copper!
• Heat!! Let's say you generate enough power to supply the entire world, plus transmission losses. The US, on average, saw about 6% power loss. Assuming those losses are roughly equal to the power lost over our entire system, which is producing about 16 TW (the total average power in use according to Cort Ammon's favorite Wikipedia page), we should see about 960 GW of heat loss. The sun adds roughly 300 TW of heat energy to the Earth (according to this page, anyway). That means energy loss from the system is roughly 0.32% of the energy from the sun. But that's with today's energy usage; free energy will mean a lot of growth, which means a lot more energy. If the world's power demand increases by a factor of 10 (a conservative estimate; currently, 1/4 of the population of the world lacks electricity), so will the heat due to power loss - 9.6 TW, or 3.2% of the power delivered by the sun. That amount of heat energy will have a significant impact on the heat of the planet.

## Material Transport

What about moving supplies? It's possible, of course, but you'll need to have a pressure-adjusted room available. If one portal is in a location with a higher atmospheric pressure - say, a few feet higher above sea level - the ambient air pressure will push air through. A little pressure difference is fine, but if there is enough of a difference, the wind blowing through the portal will be gale force - which means pushing materials through will be really hard, or really easy. And I'm quite sure delivering a pallet of tools at tornado-wind-speed is a bad idea.

Assuming one portal is in a room where it is possible to stabilize pressure, and the other is used to transport materials, it shouldn't be too much trouble... except that there are only two portals. Which means that they will only be able to move to one location at a time... much like a standard airplane. That's fine if you need to move a lot of stuff, but with a round opening of only 6 meters at the widest, you won't be able to move a lot of really big stuff. Only things that already fit in airplanes or shipping boats. In reality, that's not going to get you much of anywhere.

## Accidents and Not-So-Accidents

All technology has downsides; nuclear power, for instance, can leave a smoking radioactive crater if used improperly. That's bad. Misusing these portals? That's much, much, much worse. Here are a few examples of What Not To Do, with the best case in every example being "the portals are destroyed and stop working":

• Drop one portal into the ocean. The tremendous pressure will cause water to blast out of the other portal. Current technology would be unlikely to be able to fetch the other portal, either; not only would the pressure be too strong, but anything that got close enough to grab it would get sucked through. If the portal is transported across an ocean, there is a chance on every trip that it will end up in the drink.
• Drop one portal into an active volcano, or other unfortunate location. Best case, a bunch of lava ruins someone's day; worst case, the sudden cooling causes the volcano to erupt, and a bunch of lava ruins a lot of people's days.
• Allow it to be stolen. Between terrorists, governments, and corporations, there should be some serious security for both portals. Because if it's stolen, then it will be stolen again, and end up with whatever group has the biggest guns. And, of course, those guns will get stuck through the portal in short order.
• Associate it entirely with one government. A lot of other countries will be jealous of this one-of-a-kind toy set, and want their own, which will probably include "liberating" both portals. See above.
• Put them too near each other. If one portal is placed above the other, any number of objects will be able to fall through, constantly accelerated by gravity. If the two portals are placed face-to-face, even the tiniest particle will eventually accelerate to near-light speed. A few square millimeters of wind moving at near-light speed will leave quite the dent in the planet.

## Other Considerations

All this assumes the portals only transmit matter and certain forms of energy; if magnetic fields or gravity are also transmitted, even worse outcomes are available. Does pointing a portal at the ground negate gravity above it? I'm not sure I want to find out...

• I agree the potential abuses/dangers far outstrip the potential uses. The OP could then spin the tale along the lines of the road to hell proverb where everything goes terribly wrong, or have the scientist realize the danger via a thought experiment/daydream and refuse the portals. If the portals are refused then the character has proven her worthiness to the aliens who provide her with a safe way to achieve her altruistic goals. – Erik Jan 4 '16 at 22:37

Another follow-up to HDE's answer. I suggest that the power generation facility will need to be a bit more complicated than heretofore described.

The difficulty arises from the fact that the momentum of the particles transiting the portals is apparently unchanged. In effect, the particle stream is inertially floating, while the earth changes orientation. Think of a Foucalt Pendulum. On steroids.

Worst case, of course, occurs when the facility is located on the equator. Then the orientation of the particle stream varies by 15 degrees per hour. If the portal/generator assembly is not gimbal mounted, the particle stream will almost instantaneously begin to impact the edge of Portal A. In the case of a 6-meter diameter system with a 366-meter separation, the angle from one edge of Portal B to the opposite edge of Portal A is $$\theta = tan^{-1}\frac{6}{366} = .94 \text{ degrees}$$ With a rotation rate of 15 degrees/hour, all of the column will have impacted Portal B in 3.75 minutes.

Assuming that the generators are working to the last (so the remaining particle column is not experiencing a net acceleration), the total energy transferred to the portal frames is just the kinetic energy of the uninterrupted column, or $$E =\frac{mv^2}{2}$$ and for Cort Ammon's uranium/escape velocity version $$m=Ah\rho = 30\times366\times19050= 2.1\times 10^8 \text{ kg}$$ Then $$E = \frac{2.1\times 10^8 \times (1.1 \times 10^4)^2}{2} = 1.3\times10^{16}\text{ J}$$ Which is nearly nine megatons TNT equivalent. Unless the aliens are really hot stuff in the damage-resistance field, this suggests that Portal A will fail, and the entire 9 megatons of energy will be dissipated in less than a millisecond on the foundations of the power plant. It should be quite a show.

True, this is worst case, but it does suggest that the system should probably be installed at one of the Earth's poles. A North Pole installation would need to be built on the seabed, which is a complication, but it would be nearer the current majority of users. This would also have the advantage of providing a ready source of cooling water.

Assuming a pole installation, the major worry is precession of the poles, and the effect this phenomenon is left as an exercise for the reader.

This suggests, of course, that Something Must Be Done if the installation is to be placed somewhere a bit more convenient. The most obvious way to handle this is to install a magnetic field generator to slightly change the velocity vector of the particles to compensate for the Earth's rotation, but there are a few implications to be considered. First, magnetic deflection probably rules out uranium as a working fluid, unless the entire column is electrically charged. This actually isn't a horrible idea, since the entire mass has to be held in a vacuum. Assuming this isn't feasible, something magnetic like iron would have to used, and the lower density limits power production for a given velocity. Another factor is the need to reduce the diameter of the column, to allow for detection of variations in the column vector. Like the reduction in density, this will lower power output for a given velocity. Finally (and probably worst) is the need for an absolutely uniform magnetic field over a 5 meter area, since any non-uniformities will cause beam spread in the column, and we CAN'T have that.

EDIT - Another difficulty with placing the facility on the equator is that it will cease producing power, at least in a time frame greater than 24 hours. Because the flow vector will rotate 360 degrees in a day, for half the day the mass column will be trying to fall up, rather than down, and the mass will be decelerated rather than accelerated. One of the poles is definitely the way to go.

• But you're still using gravity as your power source, no? You're putting B above A, then 'dropping' things into A. At some point your turbine will reach a terminal speed, with whatever material you're using, right? And then how do you transmit that electricity to the world for good? (+1 though because it's building a strong case) – Mikey Jan 3 '16 at 22:36
• Do you think a cylinder between A & B would be enough to not have to worry about location of the two portals? Everything must "flow" between the two? – Mikey Jan 3 '16 at 22:37
• @Mikey I really would not like to attempt to mechanically redirect a flow of material traveling at 11 km/sec. – WhatRoughBeast Jan 4 '16 at 0:44
• @Mikey - The material reaches terminal velocity when the power generated (including efficiency losses) exactly equals the power gained by the column falling. Yes, gravity is the power source. And you transmit the electricity you've generated through wires, just like everybody else. Or you charge a bunch of really big batteries. Or you compress a lot of gas and ship the pressurized bottles. Or you electrolyze water to capture the hydrogen and ship that. Or....oh, for Heaven's sake. – WhatRoughBeast Jan 4 '16 at 1:06
• At the energy flow, I suspect that the currents generated in the metal itself will quickly melt it, and eventually vaporize it. And you can't easily dissipate that heat if the metal has to be in a vacuum. – Mihai Jan 4 '16 at 1:43

Chunnel anyone? A 3m "moveable hole" would be able to create a tunnel very quickly, just dump the "output" somewhere out of the way and voila, instant tunnel. All that would be left to do would be to insert some reinforcment so it doesn't collapse.

• This trick would depend on what the edge of the portal is (at least my impression of your answer is that you're planning to just push Portal A into the dirt as your "tunnel" method.) – Allen Gould Jan 4 '16 at 21:22

OP said "She wants to use it for an altruistic purpose"; combining this with @Dronz' idea gives me the following:
- drop the "Receive" portal into an active volcano;
- take the "Send" portal to your local parliament/congress/majlis/whatever;
- persuade the members to walk through it.