CaptainPanic

We have only been intelligent enough to broadcast anything for a very little while on a cosmic scale. I don't think that our species even raised an alien eyebrow (if they have any) 300 years ago, when we were will sailing around and fighting with swords on horseback. Assuming that alien technology is still limited by the light speed, they may be on their way, but just haven't arrived yet. I think it is a typical human thing to get impatient: where are those damned aliens? We're capable of space flight already for almost 5 orbits of the solar system's largest planet around the sun! That's like an eternity for us puny humans! A little comment to people demanding evidence in this thread: the OP stated already in the 1st post that this is indeed pure speculations. There is no evidence, and we all know that. If there was, this would have been announced with huge letters on the front page of every newspaper, and not by Airbrush in a thread in the Speculations forum on SFN. Since we all know evidence will not be provided, let's just endulge in speculations until we get bored, shall we? (I consider people asking for evidence in this particular thread just party poopers. Note that this comment is made as a member, not as moderator).

Isn't the problem that in the US, a policeman can never be sure that the suspect won't pull a gun and fire back, until he's dead? This just means that a policeman literally risks his life with every contact with a suspect. That knowledge is sure to bring the adrenaline to insane levels. In the Netherlands, it is common practice for a policeman to fire warning shots: they deliberately miss, by shooting into the air. And then they have to explain why they used such excessive force (police firing a warning shot it front page news here). So, while the segregation and discrimination are definitely a problem, the fact that people die seems very clearly related to only 1 thing: the availability of large amounts of guns. Because people don't kill people. Bullets do. But we risk to change the topic here. Perhaps we should continue the discussion about guns in another thread? But it would be relevant to know whether the black population in Ferguson (or any other troubled neighborhood) are known to own and use guns a lot? What do the numbers say?

First of all, there are 3 problems: 1. Extract oxygen from water, and into an inert gas (nitrogen is probably easiest). 2. Remove CO2 from the nitrogen. 3. The partial pressure of oxygen in water may be too low. All of this can be built. All the necessary thermodynamic data is available from public sources, and common design methods are available. But I doubt you want to carry the resulting factory on your back. The most basic method would be to bring the oxygen-poor gas into direct contact with oxygen-rich water (bubbling or spraying). The rate at which the oxygen will go into the gas is low, so that is a large machine. You can also use some oxygen-selective membrane. You still need a very large surface area for that, and I am not sure that anyone can build that using membranes (you would have to fold it up to create a really large surface). A negative side effect of using a membrane is that the partial pressure of oxygen on the gas side is even lower than with direct contact. You'll need some way to improve that (e.g. a compressor). And I did not even address the problem of removing the CO2 (which is probably easier though). All in all, it is probably cheaper and easier to bring some compressed air.

I guess washing yourself won't hurt, and it will make you smell nice as a bonus. But I agree with the others that it is probably not even necessary.

Your urine is 37 degrees Celsius. At that temperature, the vapor pressure of the water is about 0.06 bar. And your urine will heat the air and possibly the rest of the bottle too... and indeed, some water will evaporate. Since the bottle is open at the top, the total pressure is still gonna be the same as everywhere else... so, since you have 0.06 bar of water vapor in the bottle, you will only have 0.94 bar of air. Then you close the bottle. No air or water vapor can go in or out. And then you leave the bottle, and the temperature in the bottle drops. This means that the vapor pressure of the water (or urine) is now less. Let's assume the temperature drops to 15 degrees Celsius. The vapor pressure is around 0.02 bar at that temperature. So, if you had a very sturdy container, the total pressure would be 0.94 + 0.02 = 0.96 bar. But the bottle is not strong, and instead it just 'implodes', because the pressure outside the bottle was higher than inside, and the bottle was too weak to resist it. Vapor pressure is a very strong function of temperature. At 15 degrees, only 2% of the air above water will be water vapor, but at 100 degrees the water boils, and steam will replace ALL the air. So, if you repeat this experiment not with pee, but with very hot water (don't burn your fingers!), the implosion of the bottle will be more severe. (Also, make sure your plastic can withstand the hot water - some plastics melt below 100 degrees!). So, no air escaped. Instead, water vapor condensed, and liquid water requires a LOT less volume than its vapor. Satisfying curiosity is what we do at this forum. Welcome!

If you are still a teen, your medicine is called time. It hurts, and it takes longer than you like, but you will get over it. To speed things up, you might consider traveling, or otherwise changing your environment so that you are not reminded of your lost love. Also, trying and failing is a good method to get over a girl. Try to approach her, and if she doesn't want you, at least you can stop thinking "maybe...". The medicine to choose your potential partners more rationally is called life-experience. Again, you will learn that eventually. You're not even 20. You are supposed to be a bit stupid about it at that age (no insult meant - just a joke with some truth in it). The best medicine against falling in love altogether is called "working in the off-shore business". Not many women there. For the large majority of people, no medicine is needed for an impossible love or a broken heart. I think that medicine is only given if you suffer from a mental disorder. In that case, seeing a doctor is highly recommended. This forum is NOT a place for medical advice.

! Moderator Note In my role as moderator, I would like to advise people who think that a discussion is going round in circles (or that the topic has otherwise been depleted) to stop participating. Do not continue a thread just to have the last word, or to "win" a discussion. If someone is here to learn, they will read your valuable posts again. If the other participants are here to "win" a discussion, then any reply from your side will not help anyway. Please note that I am not suggesting that this discussion is done, and this is not an official warning to anyone. I am not moderating the contents here. Anyone is free to continue. It is just the above sentence (in the quote) that triggered me to make this friendly comment. Please stay on topic, which means you shouldn't respond to this moderator tip.

Ah, thanks for clarifying. I misread that indeed. Thanks for the reply btw. It is interesting to see how the laws are quite different. It does make sense to be more strict in the US, since wildlife (small birds especially) haven't had the chance to adapt through evolution to cope with small cats. Even the smallest bobcat is larger than most housecats, so I assume that they hunt different prey. Just an idea btw, there are bird feeders that are cat-proof. A quick search on the web showed me several different concepts. I assume that likewise there may be cat-proof bird nests. While I think that in Europe, it is just natural for birds to be hunted by cats, it doesn't hurt to provide birds with a cat-proof shelter, especially in an urban environment where there are plenty of cats, and not too many birds. To people who want to get a cat and live in a city, I would recommend to go to the animal shelter, and choose a grown-up cat whose character is already developed (and known by the people running the animal shelter). Do NOT get some really adventurous athletic cat. Those just get themselves killed in traffic. Get instead some lazy coward. They will still hunt for pests (mice) around the house. They will be better companions, and will live longer. And as a bonus, they won't climb into the highest trees to kill off all the birds of the neighborhood. (Note that this is an opinion, and based on just a personal experience).

! Moderator Note Homework Help Rules A simple reminder to all: this is the "Homework Help" forum, not the "Homework Answers" forum. We will not do your work for you, only point you in the right direction. Posts that do give the answers may be removed. So Chikis would you explain where you have got to in solving this problem and what has stopped your progress - hopefully members can then help you to overcome your difficulties yourself.

Thanks all for the update. It's clarified things for me. The problems seem to have long historical roots, and seem also deeply rooted in the current society. Will this problem eventually solve itself, you think? If not, what would be the 1st step that the government (or any other party involved) should take to move this in a positive direction?

swansont, you seem to put all the blame with the government (and its institutions such as the police). According to you, should I see the black population of the south (or at least those of Ferguson) as victims? Or could they do something about their situation too? Looking at a situation with which I am more familiar, the Netherlands, I observe particular groups of immigrants who are more integrated and seem to be more successful than other groups, while I'd like to think that they have (at least on paper) equal chances. I am of the opinion therefore that there is certainly a task for groups (or individuals) to take some action themselves. What is preventing a black person from renting a house in another neighborhood with better chances? It can't be only financial (because blacks are not the only poor people). Is part of the segregation perhaps by choice? (Edit: I read now that this may sound like I ask a rhetorical question, but it is an open question, because I really don't know). I never believe that there is only 1 party to blame for any conflict, even if there is one obvious dominant party (the government in this case). Btw, note that I do not disagree with anything you posted.

I am not an American, and I struggle to fully understand the cause of the riots in Ferguson, Missouri (link to theguardian.com). Obviously, the shooting of an unarmed black man living in Ferguson was for many people in at town the final straw. But there is surely a deeper problem than that. Is it that black people feel discriminated? Is it that the police are scared shitless patrolling the poor areas, and shoot much too quickly because of that? Is it because there is no good communication between law enforcement and local inhabitants (no understanding)? Can one even point out a single problem that is the major issue? I'd like to hear some input about this, because I just don't understand the actual issues. However, while I don't understand the problem, I think the solution is the same as in every conflict: Get both parties to talk to each other. The government should take every initiative in that dialogue, while enabling the locals (who are far less organized than the government) to explain their griefs. It seems however that the government takes quite a different approach, demanding the peace returns first and trying to achieve that with a massive show of force. Escalation is a real threat here. I'm curious how others explain the problem, and what solutions you suggest.

Do you live in a country where cats were not native? Regarding protection of birds: In Europe, where cats naturally occurred also without humans around, (the wildcat), I see no reason to protect the wildlife from cats. We already have natural parks to protect wildlife. The actual problem is just the huge population of humans, who took over the habitat of all kinds of wildlife. Cats only hunt for small birds and mice (sometimes a rabbit). Birds are adapted to this, and typically too smart for cats, but there are always a few stupid ones building a nest at 2 meters above the ground (cats don't need to climb for that, they just jump straight in). I consider that the bird version of the Darwin awards. Cats catching mice do us a favor. Regarding the nuisance of cats using your garden as a toilet: I think that in the Netherlands, if you trap someone else's cat and then remove it to another place (even if this is the authorities) this is considered theft, because a cat is property of someone. Not 100% sure though, but I have never heard of a cat being delivered to the authorities. If a cat poops in your garden, in the Netherlands, the owner of the cat is in violation of the law though. A major problem is of course to find out who is the owner of a cat. A good relation with your neighbors helps here: you might just ask. Perhaps a neighbor can keep the cat inside at certain times when it is most likely to poop. You do need to gather legal evidence though before you can proceed legally. If your garden is used by multiple cats, then your garden might be on the border of several cats' territories. Best solution is to get your own cat, who will likely protect its own territory. [edit] I admit that I am heavily biased when talking about cats. The above text should probably not be considered an objective reply.

It's an interesting thought. I'd be curious to know how large such a relay vehicle would be for it to even pick up a signal. Its technology would be relatively simple, I'd like to imagine... but the signal is so faint. The major problem will be the receiver. The space communications complexes used here on earth use massive antennaes to send and receive any signal. (source) Here on earth, there is a lot of noise, so these stations are placed in locations with minimal interference. Maybe a space-based station could be smaller still. But look at the size of these things... even a small communications platform would be massive. The costs of launching one would be huge. And if you launch a smaller station, you still need to travel a LONG way with your space relay before the shorter distance is compensating the much smaller receiver than the stationary ones here on earth. Obviously, another pratical problem is that for the first couple of years, your relay wouldn't necessarily be closer to the Voyager craft, since trajectories are somewhat circular around the sun, and slingshots around planets must be used to get going. You might actually travel "the wrong way" for the initial years.

Swearwords are listed in the dictionary, but the use of them is typically not acceptable. Exactly.

I enjoy reading Bad Astronomy. It's a blog with approx. one update per day. The posts usually give good explanations of new developments in astronomy (but also sometimes other important scientific events, or more rarely, politics).

! Moderator Note That "oppression" was done my me, in the role of moderator. So, I will explain one last time. Your posts simply violated our rules, section 2.7. Did you bother reading the text of that rule? In both threads I invited you to introduce that "theory" or new idea by writing it down in our forum. The problem is not the contents of the video. The problem is that we must visit another website (youtube) to get to the contents. Contents must be put on our forum, so we can participate without clicking on any external links. At no point did I tell you it is illegal to introduce whatever new theory. However, if your intention is only to generate views to a Youtube channel (or sell viagra for that matter), then you violate our rules. And as I mentioned in at least on of the other moderator notes, we have a special Speculations forum where you can post speculative theories. The discussion about the rules ends here. Do not reply to this mod tip.

! Moderator Note rivers82, This forum is not the place to plug your videos. Please observe our forum rules, specifically section 2.7. Because your other post also advertises the same video, which is btw 2 hrs long, so nobody will watch all that, all references to it have been removed. A next violation will lead to a spam-ban. Sorry if your post was a genuine post. There are just too many people on the internet who desperately want attention to their advertisement / video channel / blog / whatever. We must be strict. Feel free to write down the explanation of this "new theory" here in a post. If the "new theory" is a speculation, make sure to put it in speculations, which has its own set of additional forum rules. Do not respond to this moderator note in the thread.

! Moderator Note rivers82, This forum is not the place to plug your videos. Please observe our forum rules, specifically section 2.7. Because your other post also advertises the same video, which is btw 2 hrs long, so nobody will watch all that, all references to it have been removed. A next violation will lead to a spam-ban. Sorry if your post was a genuine post. There are just too many people on the internet who desperately want attention to their advertisement / video channel / blog / whatever. We must be strict. Do not respond to this moderator note in the thread.

Don't worry, when you are 27 years old, you are still green as grass, with very little experience in life, work or love. You may think you're old, and you may think you're quite a somebody by then, but you're not. That takes another couple of decades. Enjoy the fact that you can study until that age. Being a student has some huge advantages: you have lots of time, and you are very flexible with time. Use that freedom. Work, responsibility and all the other problems of life will come later.

According to wikipedia, there are 40 countries with oceanographic research institutes / universities (*), some of which have multiple institutes. If all these institutes again have people taking samples (by boat or along the coast), and we observe a trend, then yes we can say that the ocean is becoming more acidic. Some of these institutes sail the oceans with large vessels to take lots of samples too. Obviously, we cannot exclude that there are small areas where the opposite is happening... but there is enough data for a general trend. (*) Wikipedia sometimes surprises me... they have a list of all oceanographic research institutes and programs. Wow!

Obviously. Why model when you can measure? Measurements lead to certainty, while models only lead to uncertainties and endless discussions. But today we cannot measure the pH of the ocean which will occur in 2035 when the CO2 concentration is predicted to reach a certain percentage - we have to wait until it is 2035. But we want to predict today how bad it's gonna be. You could set up experiments or models to simulate it, or extrapolate it from other data... and then you run into all the issues I mentioned.

Why would a cat attack a big bird such as a seagull? That is dangerous, because seagulls are big and strong, and they have a pointy beak. If I were a cat, then I would not attack it. Having said that, there are probably some cats who are crazy enough to try it. Cats have personalities, and some are real pussies, while some are more heroic. I am not sure you can train a cat not to attack birds. They are predators and will always hunt.

Where I live, internet seems pretty open and free. I think the biggest threat to the open internet is not the censorship by governments. It is the drive by copyrights 'protectors' to block all kinds of content, either through technical changes to the internet, or through lobbying and law. But I applaud the initiative to make information accessible through other means. Are they also going to broadcast porn to countries where it is blocked? (If they will, their initiative might actually be successful, since everybody knows that the internet is 70% porn, 20% cat videos and only 10% useful information).

As far as I understand, there is a limit to how far we can see within our own universe, and it seems we cannot see outside of it. That doesn't mean there is no 'outside' to it. It's just that we don't know. In addition, it seems people are pretty certain that we will never know.