Voyager 2 Set to Reach Termination Shock

Invisible Pink Unicorn writes "A computer model simulation developed at UC Riverside has predicted that in late 2007 to early 2008, the interplanetary spacecraft Voyager 2 will cross the termination shock, the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed. At the termination shock, located at 7-8.5 billion miles from the sun, the solar wind is decelerated to less than the speed of sound. The boundary of the termination shock is not fixed, however, but wobbly, fluctuating in both time and distance from the sun, depending on solar activity. Because of this fluctuation, the spacecraft is also predicted to cross the boundary again in middle 2008. The article abstract is available from The Astrophysical Journal."

Comments

Zzzzzzz

[HomeLights]

Zzzzzz..Huh? What I am awake. Why do I care about this? Will I ever be able to travel that far? What does it meant to me? Will my pizza get to ne any slower?

And then what?

[stratjakt]

Other than "we sent something outside the solar system again", does this mean anything? Will we get any new data about "termination shock" or whatnot?

Re:And then what?

[mabhatter654]

this is the kind of thing scientists predict all the time and observe in lab experiments... but this device is actually GOING to the edge of a solar system... it's someplace human made instruments haven't been. Science at it's very purest form, simply going and observing something nobody has actually seen before.

Why do you go on vacation to foreign places.. aren't postcards and Discovery channel good enough? It's a whole lot different to say "we were there" than guessing what it would be like from a long distance.

Re:And then what?

[niceone]

It means Janeway's going to have to pretend to be thrown all over the place while bits of the ship fall off.

Re:And then what?

[Anonymous Coward]

Speaking as someone working on the project, posting anonymously for obvious reasons, I can give a little info. When the spacecraft reaches termination shock, it is quite likely that all the transistors will fall off the pcb's that make up the electronics. Chances are this isn't so bad, as their are lots of backup resistors, but if theres a leak in the spacecraft's petrol tank then it might be ignited by some arcing currents, which would probably throw it off course a bit.

Re:And then what?

[mustafap]

>Why do you go on vacation to foreign places..

I think you will find he is an american, and therefore that doesn't apply.

Re:And then what?

[Anonymous Coward]

Maybe you do work on the project. But you sound like the janitor for the project.

Why is it relevant that there are 'backup resistors' if 'all the transistors' fall off? Even if resistors were the same as transistors, all would include the backups.

Re:And then what?

[hyperstation]

hey all you armchair rocket scientists! you're feeding an AC troll. petrol tank? hahaha!

Re:And then what?

[FirstTimeCaller]

this device is actually GOING to the edge of a solar system... it's someplace human made instruments haven't been. From the Wikipedia article:

In May 2005, it was announced that Voyager 1 had crossed the termination shock...

Don't get me wrong, I think the prospect that our reach is expanding past our solar system is indeed exciting news...

Re:And then what?

[GodfatherofSoul]

Why do you go on vacation to foreign places...

OMG, underage Taiwanese hookers...in space?

Re:And then what?

[Anonymous Coward]

But what about the Delta Mark IV Hasselhoff-Dusseldorf-Kruller Flanges? Surely those should help compensate for the lack of vacuum tubes in the Minolta/Konica spinny thing-a-mabob.

Re:And then what?

[DeepBlueDiver]

Other than "we sent something outside the solar system again", does this mean anything? Again? The only man made objects travelling beyond Pluto's orbit are Pioneer 10 & 11, and Voyager 1 & 2.
Four, just four small space probes.

Sorry dude, all the space ships you see on TV are just FX. We are not (yet) exploring the galaxy.

Will we get any new data about "termination shock" or whatnot? Yeah! We may confirm that there exists this termination shock we expect to find there, or we may find our theories are wrong and there is not such "thing".

Re:And then what?

[theStorminMormon]

Other than "we sent something outside the solar system again", does this mean anything? Will we get any new data about "termination shock" or whatnot? Also, and stop me if I'm wrong, but if the probe is going outwards and the boundary isn't perpetually expanding it can't really cross the boundary twice, can it? It has to be once or thrice.

Once to get outside the boundary, twice if the boundary expands and catches back up with it, and thrice to once again get outside the boundary.

Just a thought.

Re:And then what?

[jav1231]

Should've gone diesel...I'm just sayin'... :P

Re:And then what?

[camperdave]

Once for Voyager 1, then once again for Voyager 2, making twice.

Re:And then what?

[Anonymous Coward]

And thrice for the mortal men.

Re:And then what?

[pnewhook]

Also, and stop me if I'm wrong, but if the probe is going outwards and the boundary isn't perpetually expanding it can't really cross the boundary twice, can it? It has to be once or thrice.

Actually no. The spacecraft would have crossed the boundary twice and the boundary would have overtaken the spacecraft once.

You can say you crossed the threshold of a door by walking through it. But if you stand still and the door suddenly flies past you, I don't think you can claim that you crossed the threshold.

Re:And then what?

[Anonymous Coward]

*Whoosh* ;-p

Re:And then what?

[j-pimp]

>Why do you go on vacation to foreign places..

I think you will find he is an american, and therefore that doesn't apply.

I'll bite. The USA offers more climate and geographic diversity than most countries due to its size. Lets compare leaving the USA with leaving Europe for a fair comparison.

And yes I have left the continent.

Re:And then what?

[Anonymous Coward]

... In Soviet Space, threshold crosses you!

Re:And then what?

[dan828]

Europeans in general don't understand this, and it's probably true for most of the rest of the world. From where I live I can make it to Mexico in about 12 hours of solid driving, or to Canada in about 20 hours, but in most places in the US it's a day or more of travel time to either country. In most of Europe you can be to another country in an hour or two. Now, I've lived in both Italy and Germany (for about a total of 5 years of my life), and when I'd be talking to people, they'd talk about wanting to travel to the US and all the places they'd like to see. Want to see LA, San Francisco, New York, New Orleans, Grand Canyon, Yosemite Valley, Yellowstone, etc., and expect they could manage this in about two weeks, which, by comparison, is like wanting to travel from Moscow to London and hit all the major points in between in that kind of time frame.

The reason why many Americans speak only one language or don't spend a lot of time in other countries is based in this. For a majority of Americans there is only one language besides English that is of any utility, and that is Spanish. I was once fluent in both German and Italian, but since I've been back in the US I have yet to run into a situation where I needed to speak either language. It's not like we can day trip to France or that most businesses can deliver finished products to a foreign country with a simple truck ride of 3 or 4 hours.

Re:And then what?

[MvD_Moscow]

You might have geographic and climatic diversity, but USA has literally zero cultural diversity. It's all the same stuff: dull suburbia, run down urban areas and rural areas. With the exception of NY (Manhattan), DC (downtown area) and a few other places, it's all the same crap. Strip malls, houses, cheap apartment, similar looking downtown areas...

In contrast, other parts of the world are much more diverse. Just take a look at India. Almost every state has it's own language/culture/history. Rajasthan is nothing like northern or southern India. Even a relatively small country like Ukraine has a quite a lot of cultural variety. From the Russian speaking east to the Ukrainian-speaking west.

So stop pretending that Americans don't check out foreign places because they have everything they need in their own country. Americans are so USA-centric because they are largely ignorant of foreign cultures/countries and they tend to be pretty cheap.

I just love when Americans (who know I am foreigner from the other side of the ocean) ask me whether I went back home for Thanksgiving, and I study in one of the top 25 universities in the USA. I can never understand how people can ace Calc IV without studying and yet they are too ignorant to know that Georgia isn't simply a state. It's nation with a 3000 year old history, no less.

Re:And then what?

[sexconker]

Actually...

"The Voyager spacecraft will be the third and fourth human spacecraft to fly beyond all the planets in our solar system. Pioneers 10 and 11 preceded Voyager in outstripping the gravitational attraction of the Sun but on February 17, 1998, Voyager 1 passed Pioneer 10 to become the most distant human-made object in space."

http://voyager.jpl.nasa.gov/mission/fastfacts.html
Wikipedia sucks.

Re:And then what?

[Anonymous Coward]

I will entertain your argument of semantics about the number of times the boundary is crossed:

1. The Voyager crosses the boundary.
2. The boundary expands; now it is the boundary crossing the spacecraft.
3. The spacecraft crosses the boundary for the second time.

So the article is correct! OMG!

Re:And then what?

[Artifakt]

It's possible this could be very important. NOTE: What I'm suggesting here is a long odds sort of thing, not the likelyest scenario, but it's also not impossible, maybe not even all that low probability. Science in general is frequently about a new hypothesis having low probability in the initial stages, and someone still researching it because if that hypothesis works out, it will have major implications. Many of those gambles never pay off, but Nobels get awarded to ones that do.
      There were some odd position and velocity data coming back from the Pioneer spacecraft when they reached the same distance from our sun. It's a known anomaly, and some unusual hypothesi exist.

http://www.sixside.com/13_things_that_do_not_make_sense.htm

(about halfway down)

  The likelyest scenarios probably involve instrumentation flaws, methods of calculating, and such, basically anything which would affect the data from both craft in the same way. Those scenarios are testable, i.e. by finding bugs in the code. Looking for similar effects with the Voyagers at the least will rule some of these scenarios out, as they are built with very different components from the Pioneer design. If corresponding data anomalies occur here, it will be fair to assume a common cause.
The unlikely but very, very interesting alternatives include some basic 'Laws of Physics' working a bit differently once you get far enough from a star. That's a spectacular claim, and needs a lot of proving, but I'd argue that even if the odds are, say, 100,000 to 1 against, it's worth throwing a few grad students and a cheap Beowulf cluster at the Voyager data for a summer project, to see if it links up with the Pioneer anomalies. If the odds are as good as 1,000 to 1 against, someone with their piled higher and deeper needs to really look at it.

Re:And then what?

[Anonymous Coward]

India is also a shithole of a country to add a fact to your point. If you're residing in the US most people will refer to Georgia as a State because it is in our country. Just like when someone is in Europe, chances are Georgia will refer to the country. Get over yourself. Stop trying to act like Europe is the pinnacle of human evolution. You guys have your fair share of shit shoveling, rural shitholes, and political turmoil. Just because every state doesn't drastically vary in culture of has practiced genocide on one another doesn't mean it has no culture. You're just as ignorant as those Americans you are talking about. Why are you at a US university anyway since the US sucks so much? Why not go back to the backwash city you're from and attend university there. I am sure they are much more enlightened.

Fucking Europeans man...Sometimes I hope a 2nd bubonic plague hits.

Re:And then what?

[172pilot]

Well, also, since the speed of sound depends on the density of the medium the sound is traveling through, what exactly is the speed of sound in the perfect vacuum of space? If they're just using sea-level speed of sound as an arbitrary measure to convey it to the common "non scientist consumer" then what's the point? What meaning could the speed of sound possibly have in a place where sound does not exist?

Re:And then what?

[theStorminMormon]

No no. The article says that due to the expansion/contraction of the barrier, voyager 2 will cross the threshold twice.

Re:And then what?

[theStorminMormon]

Well I wasn't just trying to be clever with semantics. It seems that the border overtaking the spacecraft is as scientifically interesting as the spacecraft overtaking the border - or is there something physically different about the border overtaking the spacecraft that makes it different and unremarkable?

The threshold and spacecraft will cross each other 3 times, right, not two. So why only talk about two?

Re:And then what?

[j-pimp]

So stop pretending that Americans don't check out foreign places because they have everything they need in their own country. Americans are so USA-centric because they are largely ignorant of foreign cultures/countries and they tend to be pretty cheap.

If your talking high culture then yes Manhattan is pretty much our epicenter. I have only been to DC on guided tours, so the only culture I experienced there was tours of the Smithsonian, government building and monuments.

Now in terms of folk culture, you are wrong. First of all the world epicenter of low culture is Queens NYC, possibly the most ethnically diverse area of its size on the planet. Secondly, if you can't tell the difference between different parts of the country then you need to open your eyes. Compare New York and California for example. Even though a small but sizable portion of the population regularly travels between the LA and NY metro areas, the cities have completely different feels. Try finding good grits in the North East, or decent Italian food in the South, minus a few places with significant migration from New York.

I just love when Americans (who know I am foreigner from the other side of the ocean) ask me whether I went back home for Thanksgiving, and I study in one of the top 25 universities in the USA. I can never understand how people can ace Calc IV without studying and yet they are too ignorant to know that Georgia isn't simply a state. It's nation with a 3000 year old history, no less.

I have two counter points to that.

First of all good at math does not mean good at history. If they are that good at math, and don't care for geography, they can survive just fine in college. I know a brilliant Mathematicians and programmer that probably didn't know where Prague was until he had to fly there to enter his physics engine into a competition. I would think that brilliant mathematicians in Georgia that do not study overseas have a narrower world view than you do. Also, I'm also sure Americans that study overseas have a firmer understanding of the world then their classmates.

As far as people asking you how your thanksgiving was, we Americans are known for engaging in mindless smalltalk. Most people probably didn't think out their statement. They also probably didn't care about your holiday. Finally how many of these people know you are in this country alone and not with your family.

Re:And then what?

[Dishevel]

Woot! /. Signed

Re:And then what?

[Anonymous Coward]

As pointed out elsewhere: sound = waves in matter.

Space is NOT empty, but filled with the solar wind (and interstellar medium beyond the heliopause). So there is some matter, and thus waves can move at a certain speed (= speed of sound).
This type of wave is of course is extremely far from human audible sound.

Re:And then what?

[RockoTDF]

....are you sure that isn't Star Trek in its purest form?

Re:And then what?

[Anonymous Coward]

All that's important about Georgia is whether it's still a part of our huge multinational coalition in Iraq, which we can't locate on a map either, and whether it's got oil that we can get into our supertankers. And that may sound ugly, but I believe that's the current state policy. We also prefer if you don't call any separatists you may have terrorists, because by terrorism, we mean anti-US terrorism.

Re:And then what?

[Anonymous Coward]

USA has literally zero cultural diversity... ...it's all the same crap. Strip malls, houses...

Everywhere in the USA has houses?! Oh my god, how bland! God you're a moron.

First off, at my university, most of our foreign grad students DO go back home for Thanksgiving, due to the break, just like most other people travel to their homes. Even if this isn't the reason they're asking you, I'm sure if I was in India people would ask me dumb shit about my Diwali plans, just because not everyone has your extraordinary intelligence and spends 100% of their time considering every facet of the most insignificant minutia.

Also, your examples of places with cultural diversity show your ignorance. While we might not be the most culturally diverse nation in the world (although it is my opinion that we are), your examples of culture are simply asinine. Try visiting one of the poorer apartment developments in Atlanta, where your dumb ass will get shot for acting better than everyone, and then walk your way over to Salt Lake City, where even the Mormons probably don't want you. The USA has freakin' cowboys. How can you say that's not cultural diversity? There are even two kinds, I'm told. We have people from every race, culture, religion, and background, and yes, in cities like new york you can even see them all. The culture from the hills of Kentucky to the deserts of the west, both coasts, from Maine to Florida, and from Washington to California, not to mention the gulf and the amazing culture in New Orleans. Literally zero cultural diversity? I'm embarrassed that one of the top 25 school in the USA let a fool like you in. Ironically, probably trying to meet diversity requirements.

I'm not saying that the US is the pinnacle of culture across the globe, but saying they have literally zero diversity? That's beyond ignorant, but you are obviously an idiot and a bigot, so I don't expect any less.

Re:And then what?

[TooMuchToDo]

I don't go anywhere without my Hasselhoff flanges. I wouldn't think of using anything else on my sub-lightspeed cruiser.

Re:And then what?

[EdBear69]

In Soviet Russia, threshold crosses YOU!!

Re:And then what?

[Darby]

I just love when Americans (who know I am foreigner from the other side of the ocean) ask me whether I went back home for Thanksgiving, and I study in one of the top 25 universities in the USA.

It *is* a vacation in this country for most people *regardless of your origin or citizenship*.
You could have gone any number of places without even thinking about doing anything "Thanksgivingish", so it's not really a dumb question. It's just like asking, "What did you do over the weekend".

Re:And then what?

[JoeShmoe950]

I'll bite. Only someone who goes from Disney Land to Disney World will say that the US lacks cultural diversity. Going from Massachusetts to Arizona is a much larger change than going from say, the US to Holland. Customs are different, climate is different, culture is different. I can honestly say it no longer felt like the "US" I was used to. Then travel over to Florida, and expect different accents, food, customs, traffic, entertainments, etc. And if you really want a shock, go visit a Navajo Reservation... You might argue that they fall under a different government, but they are still within the borders of the US. The Navajo reservation I visited felt far more like El Salvador than like Boston.

Re:And then what?

[camperdave]

No no. The article says that due to the expansion/contraction of the barrier, voyager 2 will cross the threshold twice.

Yeah, sorry about that. I misread something somewhere along the line.

Re:And then what?

[Propaganda13]

Obviously, you've visited a few cities as a tourist. You've fallen for tourist view of any city, visited landmarks, etc. If you've lived all over the US, you would have realized that large cities have ethnic neighborhoods where English is not always the first language. Polish, Spanish, Italian, Hmong, Irish, etc. Hell, English isn't always understandable from various parts of the country.

I asked my co-worker what she was doing for Thanksgiving. She was going back home... to India. I may even ask her what's she's doing for Christmas even though she's not Christian.

While there are dumb, socially-inept, or culturally unaware Americans, are you sure they know you're from the other side of the ocean? A Georgian (country) accent isn't enough to say you're from another country.

Re:And then what?

[MvD_Moscow]

LOL, I love the comment about India being a shithole. Just shows how much you know foreign countries.

I never said that Europe is the pinnacle of human evolution. They have their own set of problems, they let racism take priority over economic interests unlike Americans who are racist but will let you work in the USA if it economically benefits. Europe has fuckloads of bad things about it. But that's not my point...

My point is that culture within the USA tends to be very similar. It's pretty much the same shit everywhere. Strip malls, ghettos and downtowns. There are very few landmarks worth visiting if you are not American. Compare the landmarks in say Washington with any major European city.

The reason why I study in the USA is because I am not a dumb asshole like you. America has a better University system and it has more economic opportunity if you are a non-citizen (compared to Europe). Unlike you, I am not some mad fanatic who gets insulted by every random thing you say about their country. Get over it man, America has no culture. All your public holidays are just consumerist rage fests, you have no real history, you have very few cool landmarks (with the exception of NY). But that doesn't mean USA is a pile of shit, what it lacks in culture it makes up for in economic competitiveness.

It's funny that you talk about genocide considering that USA was founded on the mass eradication of the Native American population.

Chill out man, nation states are a load of bullshit anyways.

Re:And then what?

[MvD_Moscow]

Dude cmon, comparing California to NY? You've been living in the USA for way too long. Yeah, of course their different, but look at the scales involved. For 95% of the world population, it's the same shit. Of course, I am not saying that every part of US is identical. If you want differences, try comparing Cairo with Tallin. We'll see how different New York will feel from California.

Regarding the math vs geography thing, I think not knowing about the existence of nation (let alone actually knowing anything about it) is pretty fucking bad. I mean it's common knowledge. It's not rocket science, it's like not knowing about colonialism or communism. I am pretty sure mathematicians in Georgia wouldn't get confused between a local administrative region and a nation.

Regarding the whole Thanksgiving thing. I forgot to mention that the kid implied that I would be going back home to have Turkey with my family, which pretty stupid considering Thankgiving is more about celebrating 'Native American genocide'.

Re:And then what?

[MvD_Moscow]

Yadda yadda bla bla. I am fool for questioning American cultural diversity... Get the fuck out of your suburb and check out the world. Let me put it this way: compared to every other country I've been to (17 + Uzbekistan where I stayed for a day when I was like 3), USA has a pretty bland culture. For a country this size, it has very little variety and culture in general.

If you think I am wrong in my conclusion, you can go fuck yourself. Spend a fortnight in Paris and a fortnight in say LA and then tell me which experience was better. Having different kinds of immigrants in the ghetto is not culture. USA is good at something and sux for other things. It's in terms of economic opportunity and economic growth. It sux in terms of culture and partying (frats? fuk that shit! And why don't clubs stay open until at least 4am. How can a club close at 2am? Americans really need to stop Christians from enforcing social policies).

"I'm not saying that the US is the pinnacle of culture across the globe, but saying they have literally zero diversity? That's beyond ignorant, but you are obviously an idiot and a bigot, so I don't expect any less"

I though you believed that USA is one of the most culturally diverse nations on the planet?

Re:And then what?

[MvD_Moscow]

LOL, have you been to Holland? Are you seriously saying that there is bigger difference between Massachusetts and Arizona than between USA and Holland. You have no clue what the fuck you are talking about.

I'd like to check out an authentic Native American reservation, hopefully one that does not include a casino...

Re:And then what?

[Anonymous Coward]

My point is that culture within the USA tends to be very similar. It's pretty much the same shit everywhere. Strip malls, ghettos and downtowns. There are very few landmarks worth visiting if you are not American. Compare the landmarks in say Washington with any major European city.

I don't really see how you can say that. It'd be like me saying "Those European countries are all the same. See one castle or palace and you've seen them all." There's more to culture than fancy landmarks.

It's funny that you talk about genocide considering that USA was founded on the mass eradication of the Native American population.

Maybe they took their motivation from the crusades...

Re:And then what?

[MvD_Moscow]

I don't really see how you can say that. It'd be like me saying "Those European countries are all the same. See one castle or palace and you've seen them all." There's more to culture than fancy landmarks. I don't know, go visit Paris for a week and then stay in DC for week. I'll let you decide... Yeah, there is more to culture than fancy landmarks. But there is also more to culture than suburbia, strip malls and commercialized entertainment.

Maybe they took their motivation from the crusades... OMG, didn't I already tell you that I am not promoting any geographical region. I don't give a fuck where you are from, what you believe, as long as you don't engage in any active form of discrimination and don't tell me what's right and wrong I don't care who your are. Btw, I don't recommend you go to any other countries other than Canada or Mexico. I done am with you.

Re:And then what?

[atamido]

I'm not entirely sure how exactly this is related to Voyager 2 and the termination shock, but your comment is too interesting to pass up.

Your comments seem to focus on the fact that there was extremely limited permanent structure building in the area occupied by the United States 500 years ago. 500 years ago towns in Europe and other places were building structures using ideas and materials there were essentially isolated from each other. This resulted in cities that look significantly different from each other. The US on the other hand already had decent communication and transport systems in place by the time structures of significance were being built. This resulted in a lot of shared ideas and materials being used to build cities, and so less general diversity. There are still a lot of specific differences due to differences in climate, immediate materials, and cultural differences. Still, it's not like the difference between pyramids and castles.

Of course, if I want to see castles and pyramids, I have to spend a small fortune (by my standards) and travel half way around the world. In the US I can go on a road trip and see quite a bit for significantly less money (but still not that many pyramids). There are places in the US where I can barely understand the spoken language because it is so different. The foods (mostly derivatives from all over Europe) vary quite a bit too. This summer I went to see several sets of American Indian ruins there were thousands of years old. I've seen many different buildings of American cultural significance, and enjoyed the differing city planning and building styles. They are certainly not all ghettos and suburbs (but then suburbs are an American culture that I see other countries try to imitate).

You may laugh, but I had to Tallin to find out what/where it was. My geography skills have always been pretty poor, but this isn't surprising. Americans have a hard time learning about the rest of the world because it is so far removed from them. Estonia? Usually you learn about other countries' histories by how they relate to your own. I honestly can't think of how Estonia relates to the US. I've never met anyone from there. I've never knowingly had any economic trading or seen products made in Estonia. It doesn't crop up on movies (except Encino Man from 1992), the news, or TV shows. Relevance of knowing where Estonia is to the American people at large is somewhere close to zero. You have to spend time and effort learning things to live your life, and I'd have to say that most people are better off learning something else.

Yes, I realize that makes me sound like an ego-centric American, but it just makes sense. I don't spend any time learning sewing techniques, and they have a lot more relevance to me in my daily life as a sysadmin then Estonia. My brother speaks Dutch, but has lived in the US for the past decade where he has had exactly zero opportunity to speak to anyone in Dutch (though he has managed to try and sound smart by providing some basic etymology for the random Dutch word we come across). Guess how much time he spends practicing it now? Can you guess how much time I've spent learning words from him?

If Estonia, or whatever other random country, comes up, I'll do exactly what I did tonight. Look it up and learn exactly what I need or what to know about it. Just like I do for everything else.

Genocide? You keep using that word. I do not think it means what you think it means. Thanksgiving traditionally has it's basis in the original European settlers to the Americas being thankful for the local American Indians saving them all from starvation one winter. And while a lot of the European immigrants purposefully killed a lot of them and drove them off their land, they weren't interested so much in genocide as much and just taking all of their land. The Nazis were trying to round up all of the Jews and kill them. That's genocide. Early American immigrants were trying to round them all up on their land and send them someplace else.

Re:And then what?

[j-pimp]

Dude cmon, comparing California to NY? You've been living in the USA for way too long. Yeah, of course their different, but look at the scales involved. For 95% of the world population, it's the same shit. Of course, I am not saying that every part of US is identical. If you want differences, try comparing Cairo with Tallin. We'll see how different New York will feel from California.

If you want truly identical cities, compare Manhattan to Quebec. You are right that 95% of the world wouldn't care if you made them realize the difference. However, I pride myself in noticing these things.

Regarding the math vs geography thing, I think not knowing about the existence of nation (let alone actually knowing anything about it) is pretty fucking bad. I mean it's common knowledge. It's not rocket science, it's like not knowing about colonialism or communism. I am pretty sure mathematicians in Georgia wouldn't get confused between a local administrative region and a nation.
Regarding the whole Thanksgiving thing. I forgot to mention that the kid implied that I would be going back home to have Turkey with my family, which pretty stupid considering Thankgiving is more about celebrating 'Native American genocide'.

I am sure that there are plenty students that aced the equivalent of CALC IV in the country of Georgia that don't know where the state of Georgia is, or Puerto Rico. No education system in the world can will prevent the creation of idiot savants.

Regarding the origins of Thanksgiving, its realyl has little to do with celebrating the "Native American Genocide". It's origins were that of English Harvest Festival. The puritans, and later colonists were thankful for their crop. As a matter of fact colonial thanksgiving would be scheduled each year to coincide with harvest.

One more thing, Georgia, as with all 50 states is of a higher status than "a local administrative region." Of course I don't expect a foriegner on a student visa such as yourself to understand how our government is supposed to work.

Re:And then what?

[MvD_Moscow]

Your comments seem to focus on the fact that there was extremely limited permanent structure building in the area occupied by the United States 500 years ago. 500 years ago towns in Europe and other places were building structures using ideas and materials there were essentially isolated from each other. This resulted in cities that look significantly different from each other. The US on the other hand already had decent communication and transport systems in place by the time structures of significance were being built. This resulted in a lot of shared ideas and materials being used to build cities, and so less general diversity. There are still a lot of specific differences due to differences in climate, immediate materials, and cultural differences. Still, it's not like the difference between pyramids and castles.

Of course, if I want to see castles and pyramids, I have to spend a small fortune (by my standards) and travel half way around the world. In the US I can go on a road trip and see quite a bit for significantly less money (but still not that many pyramids). There are places in the US where I can barely understand the spoken language because it is so different. The foods (mostly derivatives from all over Europe) vary quite a bit too. This summer I went to see several sets of American Indian ruins there were thousands of years old. I've seen many different buildings of American cultural significance, and enjoyed the differing city planning and building styles. They are certainly not all ghettos and suburbs (but then suburbs are an American culture that I see other countries try to imitate).

Yeah, I guess when you get to this point, it goes down to a matter of taste. Some ppl might prefer 'the variety' of the USA, while others prefer the 'variety' that the rest of the world has to offer. I am sure the fact that transportation networks in the USA are well developed, the USA is relatively isolated and that Americans are cheap can contribute to people's tastes. Let's put it this way, for me, most of my non-American friends and a majority of my American friends who had the opportunity to travel abroad, USA's cultural level doesn't cut it. I am glad that exploring the USA alone is working out for you and I'd like to check out more of the USA as well, but overall I don't find USA to be as interesting as other places I've been around the world.

You may laugh, but I had to Tallin to find out what/where it was. My geography skills have always been pretty poor, but this isn't surprising. Americans have a hard time learning about the rest of the world because it is so far removed from them. Estonia? Usually you learn about other countries' histories by how they relate to your own. I honestly can't think of how Estonia relates to the US. I've never met anyone from there. I've never knowingly had any economic trading or seen products made in Estonia. It doesn't crop up on movies (except Encino Man from 1992), the news, or TV shows. Relevance of knowing where Estonia is to the American people at large is somewhere close to zero. You have to spend time and effort learning things to live your life, and I'd have to say that most people are better off learning something else.

I would question your assertion about Estonia being removed from USA. I would agree that average American can easily ignore Estonia's (and pretty much 90% of the world's nations') existence and get away with it, but that doesn't mean that it makes sense to ignore it. This kind of attitude is what gets you guys into messes like Afghanistan/Iraq/Vietnam. You guys don't jack shit about these countries and you allow your politicians to do whatever the fuck they want as long as say some BS like "Terror, WMD, Terror, Saddam Hussian, Terror, WMD, Iraq". This kind of attitude is what allowed that fucktard Reagan to get away with the creation of Al-Qaeda/bin Laden. If you want to see how Estonia plays into the bigger picture, just look at what's behind your recent failures in implementing sanctions against

Re:And then what?

[MvD_Moscow]

Manhattan and Quebec? Quebec the state? or Quebec city? I've stayed in Montreal and it didn't really seem like Manhattan, although there were certain similarities.

I am sure that there are plenty students that aced the equivalent of CALC IV in the country of Georgia that don't know where the state of Georgia is, or Puerto Rico. No education system in the world can will prevent the creation of idiot savants. I don't know, I'd say the average Georgian's geography skills are probably much better than that of an average American, let alone someone who can ace Calc IV. But that might have to do more with fact the Georgia is the middle of something and people can't afford to live a sheltered, ignorant suburban life.

Regarding the origins of Thanksgiving, its realyl has little to do with celebrating the "Native American Genocide". It's origins were that of English Harvest Festival. The puritans, and later colonists were thankful for their crop. As a matter of fact colonial thanksgiving would be scheduled each year to coincide with harvest. Really, I though that it was celebration of genocide. Like the turkey is meant to represent the Native Americans or something. (read my reply to the poster before you).

One more thing, Georgia, as with all 50 states is of a higher status than "a local administrative region." Of course I don't expect a foriegner on a student visa such as yourself to understand how our government is supposed to work. Since you know so much about foreign students, you might know that most of us have to take the SAT I/II or the ACT. Guess what one of the course for the SAT II is? American History! You know some like learning new things about other cultures/societies. The reason I used the words "local administrative region" is because that's what people in Georgia (and many other parts of the world) would call a state. Not all countries have similar government system to the United States. For instance, I can't imagine anyone who speaks in Russian to use the Russian word for "state" when describing local administrative units.

From the amount of rabid (and normal) replies, I see I've touched a pretty painful spot for Americans. I wonder what that could mean...

Re:And then what?

[JoeShmoe950]

Let's see, you go to a major city in the US, you have buildings, electricity, water, thriving industry and shops, a large wealthy class, high speed internet cafes, etc. You go to Holland, all of those apply, although there are some cultural differences, there is still the "Western City" atmosphere. Now travel to a reservation, say Fort Defiance, and look at the massive poverty, the large unsettled stretches, the falling apart cars, dialup if you find a computer at all, etc. Tell me which one feels more like Massachusetts...

Re:And then what?

[atamido]

Your assertion that Americans are cheap is a bit of a low blow, it's more that transportation is different. I know lots of people in Europe, and many of them have traveled around Europe quite a bit. Heck, you can get rail passes and travel Europe for relatively small amounts. You don't have that option in the US, and just getting to Europe will cost you more than a few weeks of traveling around Europe. Plane tickets overseas cost a lot of money and time. Because less people can or are inclined to afford it, it produces some isolationist attitudes where people are less likely to travel outside the US anyway.

Heck, I could easily travel around the US for a few weeks for less than one day in Europe.

Re:And then what?

[Anonymous Coward]

Stop trying to act like Europe is the pinnacle of human evolution.

Your post only served to further encourage that sentiment.

Re:And then what?

[MadUndergrad]

"From the amount of rabid (and normal) replies, I see I've touched a pretty painful spot for Americans. I wonder what that could mean..."

It means you're being a bit of a dick, but this is an interesting subject. Anyhow, 2 things. One, the diversity of America is different from the diversity of Europe. For one, we have massive ecological and geographic diversity. Some of the taller mountains in the world, deserts, strange natural rock formations, rainforests, vast plains, the largest trees in the world, swamps, canyons, etc. Secondly, the cultural diversity isn't so much that various cities are really different, as much as the people or neighborhoods are often different even within areas. For instance, if I want Russian food I can go to my Russian friend's house. Or Vietnamese, I can go to a Vietnamese friend's house. Chinese, Mexican, same. My parents grew up in an Iraqi neighborhood....in Detroit. Yeah, our houses may look similar, but the people who live in them have very different cultural and ethnic backgrounds. That's often more than you can say for a lot of other places, where foreigners are rarer. Also, on states, they were very nearly all different sovereign countries 200 years ago, so they are more than "local administrative units."

Re:And then what?

[Rallion]

In contrast, other parts of the world are much more diverse. Just take a look at India. Almost every state has it's own language/culture/history. Rajasthan is nothing like northern or southern India. Even a relatively small country like Ukraine has a quite a lot of cultural variety. From the Russian speaking east to the Ukrainian-speaking west.

The difference is not in the degree of cultural spread, it's in the way the people are scattered. There are thousands of enclaves in this country. Yeah, okay, so the Ukraine has all kinds of variety. That's great. I'm willing to bet that there are actually groups of both Russian- and Ukranian-speaking Ukranians here. I'm pretty certain that you'll find many different categories of Indians. There are Irish communities, there are African communities (especially in the east). There are very large Asian communities (especially in the west).

It seems ridiculous that you can say there's zero culture in the U.S., then go and talk about all the variety to be found in the rest of the world. The truth is that this is a country filled with groups from everywhere. You might think that this at least means that the U.S. has no culture of its own, but I think that's wrong too. I think that the interactions between all these groups creates something new.

And, by the way, I think that's something that you really only notice if you're a resident, a member of the community. You seem to be seeing a lot of things from the eyes of a tourist -- you see the veneer, but not the nitty-gritty underneath.

Re:And then what?

[nebosuke]

YMMV. I've found Honolulu to be far more similar to Osaka than to Boston, and neither was anything like the mid-west or west coast (which itself is vastly different between, say, SoCal, Vegas and anywhere in Oregon/Washington).

In all seriousness, of the 17 countries and states of the US, in how many have you actually done one or both of the following:

A) Attended a wedding or funeral for a local-born person whom you know independently of the rest of your family.
B) Participated in a significant community activity unconnected with a university (e.g, coaching or participating in a sport, participating in local political debates/forums).

Re:And then what?

[Torvaun]

The U.S. as a nation has existed for a little over 200 years. The various Native American tribes had no interest in permanently altering the land. England, on the other hand, stretches way back to 1066. Of course they'll have a lot more really cool landmarks. Europe has castles, because they were once a viable means of defense, and were constructed in such a way that they last pretty much forever. If you're looking for recent European landmarks, you'll find the Eiffel Tower, the London Eye, a bunch of sites that are notable mostly because of WWI and WWII, and that's about it. Europe has inherited its rich culture, America just hasn't had the time, and now it may never get the chance to build its own.

Now, don't get me wrong. I have the utmost appreciation for Europe's rich heritage. But we're the historical equivalent of the nouveau riche. The only thing that will put us on an even footing is more time, and blaming the current crop of Americans for that is useless, and only causes more strife. Feel free to keep insulting us individually, though, and for things that we deserve. Nationalism shouldn't excuse stupidity.

Re:And then what?

[laejoh]

It's a whole lot different to say "we were there" than guessing what it would be like from a long distance.

You just described the sex life of the average slashdotter!

Re:And then what?

[Anonymous Coward]

WARNING: off-topic ahead.

In most of Europe you can be to another country in an hour or two

Bullshit. Most parts of Spain are 4-5 hours away from France or Portugal. The same can be said about France or Germany. Great Britain or Italy (specially the south) is much worse. Just take a map and verify it yourself (by the way, we don't have the luxury of long stright flat roads you have).

Want to see LA, San Francisco, New York, New Orleans, Grand Canyon, Yosemite Valley, Yellowstone, etc., and expect they could manage this in about two weeks

I just did it last year. Just replace New Orleans and Yellowstone for Las Vegas and Chicago (OK, the only thing I saw in NY and Chicago was the international airport but still...)

Re:And then what?

[master_p]

"Europeans in general don't understand this"

"In most of Europe you can be to another country in an hour or two."

"is like wanting to travel from Moscow to London"

Ehmm, and Americans in general don't understand that Moscow is in Europe...

Re:And then what?

[ac3boy]

Well Said.

Re:And then what?

[j-pimp]

Manhattan and Quebec? Quebec the state? or Quebec city? I've stayed in Montreal and it didn't really seem like Manhattan, although there were certain similarities.

My mistake. I meant the island of Montreal, where like NYC you cannot make a right on red. Granted it lacks the sprawl of NYC, but its a port city with a diverse immigrant population. Also both cities are older than their current sovereign governments. I think we just look at cities in different ways. However, I feel that the feel of Montreal is closer to NYC than the feel of LA is to NYC.

Re:And then what?

[Anonymous Coward]

Who would have ever thought there would be a 'shock' once we pass Uranus?

Re:And then what?

[Anonymous Coward]

Oh WOW, 4-5 hours away! That's soooooo far!

Oh wait, if you're in Nevada it takes you 8 hours just to get from Las Vegas to Reno, and you're not even leaving the state. Get some perspective. 4-5 hours is nothing. I drove that almost every week to get from home to college in Virginia, without leaving the state. And Virginia is a relatively *small* state.

I would *love* to be able to drive 4-5 hours and be in a completely different country with its own language, customs, etc. The closest I get is driving down to North Carolina and not being able to understand the natives because their accent is so bad. But even then, half of the people are mexican immigrants.

Re:And then what?

[dan828]

most =/= all

But without degenerating into the inadequacies of generalizations, the point is that for many Europeans it is easy to day trip to other countries cheaply, and it is also likely in day to day business affairs that speaking another language will be of some use. In the US this is not the case. The exception being that speaking Spanish can be useful in some areas.

As for your trip, visiting some cities and landmarks in the west and flying through NY and Chicago hardly makes your point. Other than the cities where you just at the airport, everything you note is within less than a day's driving distance.

butt wobbly

[Anonymous Coward]

word up

Re:butt wobbly

[Facetious]

Sir Mix-a-lot? Is that you?

speed of sound

[AndyST]

speed of sound... wait a minute? In which medium? I don't think there is much atmosphere up there...

Re:speed of sound

[qbwiz]

The medium is, in fact, the solar wind.

Re:speed of sound

[InvisblePinkUnicorn]

The speed of sound in the interstellar medium is much higher than it is on earth. In case you didn't know, space is not empty. Vacuum is, but space isn't.

Re:speed of sound

[Anonymous Coward]

Note: The speed of sound decreases with greater density and increases with elastic modulus. Contrary to popular opinion it does not decrease with decreasing density. Therefore the speed of sound is fairly high in the heliosphere.

My suspicion is that "in space no one can hear you scream" is true because an immense amount of power would be required to make a pressure wave audible in such a low density material. The sound would have to be much louder than what a human is capable of making. Besides the obvious physiological difficulties of having one's ears exposed to the near vacuum of space.

Re:speed of sound

[ehaggis]

Just a reminder: In space, no one can hear you scream.

Remind me again

[tompaulco]

What exactly is the speed of sound in a vacuum?

Re:Remind me again

[locster]

Exactly zero.

Re:Remind me again

[mabhatter654]

There's still solar particles out there, however sparse.. normally they move too fast for devices on earth to measure... at this point the device will be going faster than solar particles... kind of cool that the device has "outrun" it's home star.

Re:Remind me again

[lstellar]

Zero. But space is not a true vacuum. The fact that you can travel from one entity to the other creates relevance for the speed of sound. If space was infinite and truly *empty* then the limit would be negligible.

Re:Remind me again

[Veinor]

Space is not a vacuum. The speed of sound in space is about 100 km/s, according to Wikipedia.

Re:Remind me again

[kimvette]

That's what I was wondering. How can there be a speed of sound in a "medium" which does not have enough mass to transmit sound waves? I mean, I know there are sparsely-distributed particles even in "empty" interstellar space, but is the medium thick enough that there can even be a "speed of sound" associated with it? Can sound transmission in such a medium ever even be measured? I was curious and googled on desity of matter in space and found this:

http://library.thinkquest.org/C0126626/fate/fate%20of%20universe.fate%20of%20universe.mass%20density%20of%20the%20universe.htm

The most obvious technique for discriminating between an open and a closed universe is to measure the average density of matter. The Friedmann equation describes the competition between the attractive gravitational force and the expansion of the universe. The gravitational attraction exerted at the center of an arbitrary sphere cut out of the universe is proportional to the average density of matter. The measured value of the Hubble constant (H) yields the kinetic energy of the expansion of the sphere. If the present density is below the critical value at which the expansion and gravitational attraction balance, gravity cannot halt the expansion, and the universe must be open. The critical density for closure of the universe is

d critical = 3H2/8G = 5×10-30 gram cm-3

[sorry the equation got munched! -Kim]

where G is Newton's constant of gravitation. Another way to express this critical density is in the number density of atoms, which amounts to 3 x 10-6 atoms per cubic centimeter (cm-3), or only 3 atoms per cubic meter.

3 atoms per cubic meter is actually higher than I expected it would be given the immense (infinite? It certainly can't be definitively measured by any means we have, only theorised and later disproven) size of the Universe. Is 3 atoms per cubic meter enough to even have a "speed of sound" associated with it?

Re:Remind me again

[gclef]

These guys seem to think it's 100km/sec.

Re:Remind me again

[InvisblePinkUnicorn]

In space, it is much higher than the speed of sound on earth. Tens of kilometers per second, a couple orders of magnitude faster than on earth. See, space is not empty.

Re:Remind me again

[cnettel]

That number of 3 atoms per cubic meter is the average density of the complete universe, inluding stars, planets and black holes, but also including the vast void between galaxies. Any place in the Milky Way, and especially in the relative vicinity of the Sun, is "much" denser.

Re:Remind me again

[Nos.]

So, in space, they can hear you scream?

Re:Remind me again

[Sockatume]

Neither the interstellar medium nor the stellar medium is a true vacuum though. The solar wind comes out of the sun faster than the speed of sound in the interstellar medium, in the same way that the expanding sphere of gases from an explosion moves faster than the speed of sound in the air around it. The breakneck expansion of the solar wind and the pressure of the interstellar medium (such as there is) eventually come into equilibrium once you get far enough from the sun. This boundary is your shock front, or in this specific case, the termination shock. What's interesting to me is that changes in the pressure of the solar wind should set up shock waves in the interstellar medium. Please note IANAAstronomer, just an interested postgrad with Google at hand.

Re:Remind me again

[AragornSonOfArathorn]

So, in space, they can hear you scream? Yes, but they have to take off their helmets to hear you. And then they scream.

Re:Remind me again

[inviolet]

There's still solar particles out there, however sparse.. normally they move too fast for devices on earth to measure... at this point the device will be going faster than solar particles... kind of cool that the device has "outrun" it's home star.

If that is true, then the device will begin slowing down, ever so gradually, as it runs into random interstellar particles, and as it runs over the slower particles of the solar wind.

Re:Remind me again

[Orange Crush]

IANAP, but I think "undefined" would be a better answer. Sound is just vibrations travelling through matter. True vacuum, being the absence of matter has nothing for the sound to travel through so there is nothing to measure--zero is a measurable value, after all.

Re:Remind me again

[magarity]

See, space is not empty
 
It's full of stars...

Re:Remind me again

[Sockatume]

The difference between our atmosphere and the "vacuum" of space is quantitative, not qualitative. Solids, liquids, and gases (even very, very low pressure gases) can all transmit mechanical vibrations (what we call sound) to some degree.

Re:Remind me again

[drachenstern]

IalsoANAP, but wouldn't that imply that light cannot travel through a vacuum? since light is predominantly viewed as electro-magnetic waves, not purely particles. And if you have light in a vacuum (since we don't speak of singular lights, "light" would imply vastly many "light(singular)"), then don't you now have a mechanism that allows for vacuum to transmit vibration?

It seems like the current definition of physicists is flawed, as you and I understand it (presumably we understand the same thing).** If vacuum cannot transmit vibration, then how does light pass through it? If vacuum is the absence of matter, then how does a light particle travel through it? These are two questions that pre-suppose the other question has been answered with the subject of the question. In other words, the general retorts are as follows:
If vacuum cannot transmit vibration, then how does light pass through it? - Light is a particle, and can therefore move through where vibrations cannot.
If vacuum is the absence of matter, then how does a light particle travel through it? - The absence of particles does not imply the inability to transmit vibration.

Yet current physics theories (as I understand them) don't tackle both of these questions at the same time.

The other thing I'm a little hazy on, how do you measure speed when there is no friction coefficient to measure against? Isn't that rather how speed is measured in the conventional sense? I realize that speed is a simple mathematical quantification of the amount of energy a unit has expended to move in a given direction, while overcoming friction (or not, if speed = 0).

Ah well, that's just me $.02

**Now, given that I am playing Devils Advocate doesn't mean that we understand two different things.

Re:Remind me again

[jbeaupre]

I got to wondering myself and did a bit of searching. Turns out that the speed of sound in space is not due to particle collisions as much as it due to magnetic interactions of the ionized atoms. It's the magnetic fields bouncing off one another. If you're curious to learn more, the place I started was http://www-istp.gsfc.nasa.gov/Education/wtermin.html. From that clue I came across http://en.wikipedia.org/wiki/Alfv%C3%A9n_wave, but I'm not about to do the math to confirm the speed of sound in space.

Re:Remind me again

[davidsyes]

Hoover Speed
Bissel Speed
Oreck Speed
Haier Speed

No, wait...

Gemini Universal Speed....?

Actually, I wonder what would happen TO a vacuum cleaner powered up and turned on in space. I wonder if it would suck to death. How long before the bag fills up?

And would a Hepa Bag or unit collect much of value?

How long would dust mites survive in space (say, not too hot, not too cold, but just in vacuum... they survive cold-water laundering...)

Re:Remind me again

[gEvil (beta)]

My God!

Re:Remind me again

[peragrin]

um RM radiation can travel through vacuum, sound can not. Sound is literally the vibrations of the medium. Normally air but other substances as well. Sonar is sound waves traveling through water. why do we use Sonar instead of Radar underwater. because EM radar waves don't travel that well through water, or other dense objects.

As for speed in space, you can judge it simply but measuring time it takes you to travel between two fixed points, or by taking measurments againist another known objects. Besides Acceleration in space matters more than speed. To get to the moon you don't travel at a fixed speed but you accelerate half way there, and then decelerate the other half. without fricition to slow you down you need some massive forward firing engines.

Re:Remind me again

[Anonymous Coward]

What exactly is the speed of the sound of one hand clapping in a vacuum?

Re:Remind me again

[StarfishOne]

yummy! Did someone mention ice cream!?! :p

Re:Remind me again

[pln2bz]

I would add to your comments an important and frequently ignored fact regarding the solar wind that it continues to accelerate as it moves away from the Sun -- even as it passes the planets.

If we're going to use the "wind" moniker, it's helpful to remind people that it is not really all that much like a wind at all in this regard -- unless you're intending an *electric* wind as happens to charged particles subjected to an electric field within a plasma physics laboratory. To date, there remains no adequate explanation within the conventional paradigm as to why the solar wind accelerates like this (although laboratory plasma physicists who don't dabble in astrophysics would wonder what all of the controversy is about). The fact that we're actually in this gigantic plasma structure too makes it a bit more difficult for astrophysicists to propose all sorts of unusual explanations for this acceleration.

I believe that we pay a heavy price for ignoring this important detail. It is not a minor fact that can be brushed aside as -- whatever it truly is -- is moving more matter in our solar system than any other force we know of. One could lucidly argue -- and people are doing just that -- that this force is playing a more important role in the universe than conventional astrophysicists will accept.

For example, I've had discussions with a person named Hank May, who has been studying the Pioneer Anomaly for some time now, and who has a rather simple explanation that the thermal blankets on the Pioneer ship have been acting as capacitors, which are responding to a weak electric field that is generated by the Sun (note that this weak electric field is not accepted by mainstream astrophysicists, although there are many plasma physicists who see no problem with it). He's been having issues getting his paper published because it defies the popular paradigms in astrophysics these days, which is a bit unusual considering that the Pioneer Anomaly is actually considered a test for mainstream cosmology. But, regardless, look at what he has to say about the issue ...

Efforts are underway to launch a dedicated mission to resolve the Pioneer Anomaly once and for all. The major experiment (planned at this stage) involves two small spheres to be tethered near the mother ship, whose positions are monitored by lasers and other devices. In my paper I attribute the Pioneer Anomaly as due to the electric field, of course, but that requires a higher negative electric charge on the spacecraft than seems reasonable. I pondered and sweated over this problem, and finally realized that the charge resides in thermal blankets which cover the outer parts of the spacecraft. The point is, the test spheres are not to be covered with thermal blankets, whereas the mother ship will (in all likelihood). So . . . . . my model would predict that the spheres will continue in a Newtonian way, whereas the mother ship will undergo acceleration towards the Sun, leading to an anomalous acceleration of the test spheres in an antisunward direction. There have been about 50 proposed explanations for the Pioneer Anomaly, and I have looked at many of them. I believe my model is the only one of the 50 that predicts such a result. Of course, as mentioned in my attachment*, the Pioneers may have accumulated the bulk of ltheir charge during their Juputer flybys, so the anomaly may not be as large with the mothership. Also, if it uses different dielectric materials in its thermal blankets the effect might be different. But in any case my model predicts some effect as I have described, however small.

Re:Remind me again

[Anonymous Coward]

...but I'd theorize that the space between the ears of a psychic medium is a true vacuum.

Re:Remind me again

[D4MO]

What if a tree falls, in space?

Re:Remind me again

[SQLGuru]

Dude, where's the Roomba?

Layne

Re:Remind me again

[bcrowell]

For a gas of a given composition, the speed of sound is proportional to the square root of the absolute temperature, and is independent of pressure. So if the average temp. of the interstellar medium is, say, 3 K, then the speed of sound out there will be on the order of 10 times lower than it is in the Earth's atmosphere.

If you think of the classic physics lecture demonstration with a speaker inside a bell jar, the reason the sound goes away when you pump out the air isn't that the remaining air is too thin to support a sound wave, it's that the speaker cone is very inefficiently coupled to that air.

Re:Remind me again

[Attila the Bun]

"Nerds" either know this stuff, or are sufficiently switched-on to work it out before opening their mouths.

Maybe it's time to throw in the towel and start publishing stories about B-list celebrities.
Slashdot. News for your average Joe. Stuff to read whist getting a hair cut.

Re:Remind me again

[Anonymous Coward]

I'm curious as to *how* dense it really is around the solar system. Let's say, when the Mars Rovers were 1/2 way to Mars, in that type of space, how many atoms are there per cubic meter, roughly?

Re:Remind me again

[BillOfThePecosKind]

I've been thinking about the speed of sound in an interstellar medium too, but I think it means that the solar wind (or particles or what have you) are traveling faster than the vibrations caused by it can propagate. Maybe? The whole "Speed of sound" label is throwing me off.

Re:Remind me again

[bigstrat2003]

Oh, get over yourself. Being nerds doesn't mean that we aren't lazy, and willing to have discussions about things we don't fully understand.

Re:Remind me again

[Anonymous Coward]

I don't know, ask Mr. Dyson?

Re:Remind me again

[Anonymous Coward]

What is the sound of one hand orbiting?

Re:Remind me again

[Kagura]

Welcome to the Electric Universe. Don't forget to check your common sense at the door.

Re:Remind me again

[pln2bz]

Welcome to the Electric Universe. Don't forget to check your common sense at the door.

And I suppose this is supposed to make more common sense ...

http://www.trustedlog.com/2007/11/26/parallel-universe-exists-we-have-evidence/

Common sense would demand that if you're observing plasma voids within the universe, then you should identify what scenarios plasmas tend to form voids within the laboratory. You know, the whole point of inflation theory was to explain a homogeneous mass layout of the universe. It was only six months ago that mainstream astrophysics advocates were claiming that this observed homogeneousness was a great "prediction" of inflation, a prediction that had been 'proven' by the WMAP data. Now that they observe that the universe is not homogeneous, rather than accepting that inflation might be wrong, the astrophysicists propose that we're seeing an alternative universe, which -- and I shouldn't have to explain this -- is a completely untestable claim. Is that the common sense that EU Theory is lacking?

I think you're confusing common sense for popularity. EU Theory is not *popular* -- yet. It makes *FAR* more sense though than the dominant paradigm today because it is largely a re-statement of laboratory plasma physics -- which constitutes 99.999% of all visible matter within the universe.

But the reason that EU Theory is not popular has little to do with the arguments. I've studied the numerous arguments at great length for many months now. There is nothing wrong with them. They are all valid and many of the advocates of EU Theory have very serious credentials. The real problem to date has been that there is no place for people like yourself to go where you can be dealt the devastating argumentative blow to your own cherished cosmology that you expect in order to change your mind. All of the Electric Universe sites are designed to suit the needs of people who have already read the books. Since you guys refuse to read books that you do not already agree with, we will have to teach you EU Theory through peer reviewed papers. Once you're being explained what EU Theory is by people who have PhD's in mathematics from MIT and people who have been reading astrophysical papers for 30 years -- something which you won't have to wait much longer to observe -- you'll come to realize that this is not a bunch of crackpots.

Re:Remind me again

[AGMW]

I suspect that "space" is indeed sufficiently non-vacuum to allow sound to travel, thereby meaning that in space you could indeed hear a scream, but I wonder if it is sufficiently non-vacuum to allow a human to scream - ie is there enough gas to allow a human to generate a sound? If you still had some air in your lungs you might be able to scream, but the pressure differential might just make you go red mist. You would always be able to use sign language to scream, of course.

Perhaps the tag line could be rephrased thus :-

"In space, you would probably not be able to generate a scream, but if you did, people sufficiently close might be able to hear you, but you could definately "sign" a scream, meaning anyone sufficiently close, and looking in your direction, could interpret your scream if they understood the varient of sign language you were using".

Hmmmm. Perhaps more accurate, but not quite as snappy methinks.

Re:Remind me again

[hawk]

>So, in space, they can hear you scream?

But, more importantly, the Enterprise cans s'wish again! :)

hawk

Re:Remind me again

[kimvette]

THANK YOU for the helpful reply. Particle collisions didn't seem to make sense but what you posted did, and those pages you referenced do look like excellent starting points.

Again, thank you. :)

Re:Remind me again

[zony]

Win!

cool

[wwmedia]

but can someone describe in layman's term what will that mean for the probe (if anything), will it change course/direction? can this negatively affect the mission/spacecraft itself?

Re:cool

[calebt3]

Yes

Re:cool

[zippthorne]

No. It will have very little effect on the actual spacecraft itself. However it will provide invaluable data (being only the second instrument ever to make in situ measurements there) to confirm and help update our models.

No matter what happens, it can't negatively affect the mission, because it is the mission. (well part of the mission, anyway) As a useless analogy, if Space Aliens came down and ray-gunned all of SETI's equipment, you wouldn't say that SETI's mission would be negatively impacted, would you?

Re:cool

[quanticle]

can this negatively affect the mission/spacecraft itself?

Technically, the mission was to study the outer planets, so its already been accomplished. NASA keeps listening to Voyager even though its mission is technically complete because its one of a select few probes on course to exit the solar system. In other words, its mission right now is to go to the edge of the solar system and report back what it sees. In this sense, Voyager is close to accomplishing its (2nd) mission.

Re:cool

[Blakey Rat]

I don't know about the spacecraft (my guess is the density is so low that even a big "shock" is perhaps a very very light shove), but didn't the mission finish something like 20 years ago? I don't think the mission is in danger. ;)

so it's wibbly wobbly timey whimey then?

[Anonymous Coward]

(sorry, a little Doctor Who humour there...)

Surfin' Safari

[locster]

Perhaps a better subject line would've been "Voyager 2 Surfin' the termination shock wave!"

Re:Surfin' Safari

[sconeu]

Maybe that means the Voyager will come up with a new Theory of Everything?

back to the future

[192939495969798999]

Does it travel back in time/come out the other side/anything else cool, or is it just like hitting a bug on the windshield? News at 11.

Re:back to the future

[HTH NE1]

Maybe it receives super ESP powers, creation of matter, exertion of force at a distance, every mental god-like power except for being able to correctly guess someone's middle initial.

Re:back to the future

[SQLGuru]

I can guess anyone's middle initial.....it's F.

Bill F'ing Clinton
George F'ing Bush
Paris F'ing Hilton
etc.

Layne

Re:back to the future

[systemic chaos]

Brock F'ing Samson

The Sky is Falling!

[Anonymous Coward]

Interesting that the sun can have variation 8 billion miles away, with its power "fluctuating in both time and distance" but Global Warming Alarmists will deny that it has any varying influence a mere 93 million miles away on the Earth. Never mind, buy some carbon credits, and we'll all be safe until the next crisis!

Re:The Sky is Falling!

[Farmer Tim]

Global Warming Alarmists will deny that it has any varying influence a mere 93 million miles away on the Earth.

You realise there's a slight difference between a planet with a magnetic field and charged particles in a near vaccuum...

Re:The Sky is Falling!

[Anonymous Coward]

I'm tired of this bullshit. Yes, the sun does have its variances, but solar output is something that can be measured directly in an extremely easy fashion. As such, the sun's energy fluctuations have been factored into climate models, and no, they don't alone explain the change in climate here on Earth. So go find some other meme to cling to.

Haven't you heard?

[ebolaZaireRules]

In space, no one can hear you scream? ... because the speed of sound in space is zero (well, undefined would probably be better)

So apart from it being a long way away, its where space (where there is no sound) is slower than sound (on earth)

?

Re:Haven't you heard?

[Anonymous Coward]

Uh. That is wrong. The solar wind is a gas plasma, and as such has a defined (though somewhat complicated to work out) speed of sound*. It also fills the space surrounding Sol. It is in effect the "atmosphere" of the Sol star system, however one that itself travels at supersonic speed outward from Sol. The termination shock is where it goes subsonic and becomes pretty much indistinguishable from the interstellar medium, the "atmosphere" of the galaxy. (There is an intergalactic medium too, which is really not dense at all).

* Speed of sound in a material is the speed at which information propagates through collisions between constituent particles. In a supersonic flow, no information can propagate upstream through collisions, the flow just changes weirdly and suddenly at "shocks" (the math works out, honest) - a "sonic boom" is a travelling shock attached to a supersonic aeroplane in a generally subsonic medium sweeping past you.

Re:Haven't you heard?

[ChrisA90278]

".. because the speed of sound in space is zero"

This is wrong. The speed of sound in space is actually very high. Much higher than here on earth. Because of the very low pressures there the amplitude of the sound waves are very low. So low you could never hear anything. But the speed is 100 or 1000 times faster. Space is a near perfect, not a perfect vacuum.

Think of it this way... There are objects as big a stars floating around why would yu not expect there is be also small thing floating around like gas molecules.

The root cause of this is grade school science. They teach "there is no air" and "you need air to make sound". This is good if you are in third grade because they can't understand "10E-12 g/cm^3"

Will its speed change?

[schwit1]

Now that the tailwind has slowed down.

Re:Will its speed change?

[ksalter]

Why would that happen? What force is acting against it?

Re:Will its speed change?

[Anonymous Coward]

Friction. Space is not a complete vacuum.

Re:Will its speed change?

[e4g4]

The force of solar wind. It probably has had a negligible impact on the speed of Voyager 2, but its effects are certainly non-zero.

Re:Will its speed change?

[Anonymous Coward]

The speed shouldn't change at all. Since the spacecraft is going X kph in some direction anyway, the only thing that crossing a boundary is going to do is slow down the acceleration of the craft, so it will go faster at a slower rate.

Then again, is Voyager riding the solar winds at all? Maybe just a little boost to its speed, but I thought that Voyager set out with an inital push from Earth and then got speed boosts looping around planets and such.

Re:Will its speed change?

[p!ssa]

Thats not true, the real speed boost came from the slingshot around Oprahs ass, followed by a Chuck Norris round house kick.

Re:Will its speed change?

[Magius_AR]

It's a very good question, especially since Voyager I sped up once it crossed the termination shock.

Voyager 2...

[jez9999]

There's a Voyager 2?! Oh God no; come back Enterprise, all is forgiven...

Re:Voyager 2...

[VJ42]

Don't worry, that was Voyager 2, Voyager 1 was in the motion picture, remember (and then quickly erase it from your memory again).

Re:Voyager 2...

[Anonymous Coward]

Didn't voyager 1 eventually become the borg?

Re:Voyager 2...

[wolverine1999]

There was another Voyager in Space:1999.. that one ends up obliterating alien races who then come back to kick our asses...

Re:Voyager 2...

[fm6]

I was googling voyager and vger and discovered that there was a video game, the premise of which was that vger created the Borg. Barf!

When TOS was canceled it was a major tragedy in my pathetic little adolescent life. But ever since it came back I've been dreading every encounter with it. ST has become this big stinking magnet for formulaic hack writing and pretentious dweeb storytelling. Worse, it's surviving every attempt to put it out of our misery. It's the Franchise That Would Not Die! It's a culture eating zombie! Somebody save us!

Worst. Write up. Ever.

[Anonymous Coward]

"The boundary of the termination shock is [...] wobbly, fluctuating in both time and distance from the sun"

Are you SURE that it fluctuates in time from the sun, or do you actually mean that it fluctuates (only) in distance from the sun? Then there's this beautiful piece of prose:

"... Voyager 2 will cross the termination shock, the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed. At the termination shock [...] the solar wind is decelerated to less than the speed of sound."

And finally:

"Because of this fluctuation, the spacecraft is also predicted to cross the boundary again in middle 2008."

Ignoring the poor English, care to explain the logic behind this? Surely, going from inside to outside, Voyager 2 will have to cross the boundary an odd number of times? Ladies and gentlemen, I suggest that this is worst article EVAR on slashdot. I rest my case.

Re:Worst. Write up. Ever.

[DigitalReverend]

I don't understand how this was moderated a troll. You are absolutely correct on every point. I wish my moderator points were active today, I'd at least try to get you back to 0.

Re:Worst. Write up. Ever.

[Kohath]

Surely, going from inside to outside, Voyager 2 will have to cross the boundary an odd number of times?

I was going to ask this same question.

I wonder what's wrong with the mods who moderated you down?

Re:Worst. Write up. Ever.

[ChinggisK]

Ladies and gentlemen, I suggest that this is worst article EVAR on slashdot. Obviously you didn't see the article earlier today about how the House of Reps has declared the internet to be a terrorist threat.

Re:Worst. Write up. Ever.

[Remus Shepherd]

The writeup didn't bother me at all. But then, I *am* a scientist.

Are you SURE that it fluctuates in time from the sun, or do you actually mean that it fluctuates (only) in distance from the sun?

The termination shock fluctuates in distance because it's an interaction between the heliosphere of the sun and the interstellar medium. Parts will experience more drag due to magnetic fields, and thus be closer to the sun than other parts of the shock. It fluctuates in time because the sun's output fluctuates in time -- when the solar winds are stronger, the corresponding parts of the termination shock will be further away. So it fluctuates in both time and distance, and depends upon solar activity. Just as the writeup said.

Ignoring the poor English, care to explain the logic behind this? Surely, going from inside to outside, Voyager 2 will have to cross the boundary an odd number of times?

Nope. The solar winds overlap each other. A weak wind will create a shock terminator nearer to the sun, while a stronger wind will create one further away. And they hang out there for a long time after they were generated. Apparently the astronomers looked at solar activity and calculated that Voyager 2 will hit two shocks -- one from a weak, but earlier wind and one from a stronger but more recent wind. Makes perfect sense.

And you have some sort of problem with them describing the terminator shock as the boundary where the solar wind decelerates to the 'speed of sound'? That's accurate. Remember that the solar wind is composed of charged ions, and that we're talking about the speed of sound in a plasma. When the particles go below the speed of sound, then random magnetic fields suddenly become a greater influence than the outward driving force of the sun. There will probably be lots of magnetic turbulence, although nobody really knows what to expect.

The writeup was technical but accurate as far as I can tell. Sorry it if was too geeky for you.

Re:Worst. Write up. Ever.

[Niko.]

I was wondering exactly that. Obviously, in space the speed of sound in air is irrelevant. It's also meaningless in a total vacuum. I know space is not a total vacuum, but I'm still surprised to hear you describe the solar wind as a plasma. I know its charged ions are the constituents of a plasma, but does the solar wind have anything like the density necessary to constitute a "medium" in which waves can form? I would think it'd be orders of magnitude too thin for anything to propagate at all.

Same question for the "interstellar medium". OK, not a total vacuum, but how does a few particles per cubic kilometer constitute a medium?

Re:Worst. Write up. Ever.

[skeeto]

A good point, but it didn't say that the second crossing would be the last time. It was probably just noting that there will be two crossings in 2008. Maybe it will cross the third time in 2009.

Since this is /., you are probably right anyway. :-P

Re:Worst. Write up. Ever.

[E 99]

The termination shock fluctuates in distance because it's an interaction between the heliosphere of the sun and the interstellar medium.

Well... the interstellar medium plays a part further out, but the termination shock is the interaction between the areas of supercritical and subcritical flow of the solar wind.

Re:Worst. Write up. Ever.

[noidentity]

The "cross boundary an odd number of times" is a logic thing, even more fundamental than physics. If a boundary crossing is defined as doing from super-sonic to sub-sonic, or vice-versa, and this ship is moving on average to slower-moving particles, then it must cross an odd number of boundaries. It will cross at least one. If it crosses more than one, the second one will be from slower to faster moving, and then it's going to cross at least one more fast to slow one at some point.

Re:Worst. Write up. Ever.

[gardyloo]

I know its charged ions are the constituents of a plasma, but does the solar wind have anything like the density necessary to constitute a "medium" in which waves can form? I would think it'd be orders of magnitude too thin for anything to propagate at all. If the constituent molecules (or ions, whatever) can influence each other at _all_, then it's dense enough to carry waves. Maybe not fast ones (compared to c in air near the earth), and maybe not easily detectable, but they're there. Heck, clustering of galactic "molecules" are wave phenomena, over tremendously long time scales, and with tremendously low spatial density (a galaxy every thousand light-years?).

Re:Worst. Write up. Ever.

[lawpoop]

Are you SURE that it fluctuates in time from the sun, or do you actually mean that it fluctuates (only) in distance from the sun? The termination shock fluctuates in distance because it's an interaction between the heliosphere of the sun and the interstellar medium. Parts will experience more drag due to magnetic fields, and thus be closer to the sun than other parts of the shock. It fluctuates in time because the sun's output fluctuates in time -- when the solar winds are stronger, the corresponding parts of the termination shock will be further away. So it fluctuates in both time and distance, and depends upon solar activity. Just as the writeup said. OK, but isn't it redundant to say that the termination shock fluctuates in both distance *and* time?

It's like saying that a car's speed varies in both velocity and time -- in other words, at one moment it might be going 40 MPH and at another 60 MPH. But we know that at no single moment in time will it be going both 40 and 60 MPH. As human beings, we don't expect phenomena like this to have two values at the same time, so saying that it varies in both velocity and time ( or distance and time ) is redundant. Simply saying that "it varies" implies, in common language, that it varies throughout time: that it only have a single value per unit of time. Every day phenomena don't vary in a single instance of time.

Now I know that the universe is a strange place where phenomena exist that defy our intuitive physics, but I think this one is rather obvious. The phenomenon is simple, and the terminator varies only in distance. The fact that is also varies in time is implicit in saying that it varies in distance -- we don't consider the possibility that it has multiple distance values in a single moment of time.

I guess the only person who might need this explained to them is perhaps a scientist who is used to dealing with quantum phenomena on a daily basis, and may not be making the same assumptions as other people ;)

Re:Worst. Write up. Ever.

[Anonymous Coward]

Ignoring the poor English, care to explain the logic behind this? Surely, going from inside to outside, Voyager 2 will have to cross the boundary an odd number of times?

It didn't say it would be the last time. Maybe that's when it will be overtaken by the boundary, and then it will cross again some time later.

Re:Worst. Write up. Ever.

[Smauler]

The termination shock fluctuates in distance because it's an interaction between the heliosphere of the sun and the interstellar medium. Parts will experience more drag due to magnetic fields, and thus be closer to the sun than other parts of the shock. It fluctuates in time because the sun's output fluctuates in time -- when the solar winds are stronger, the corresponding parts of the termination shock will be further away. So it fluctuates in both time and distance, and depends upon solar activity. Just as the writeup said.

Fluctuate, by definition involves time. Saying "The price of oil fluctuates wildly" is ok, because obviously you mean it fluctuates over time. Saying "The time and price of oil fluctuates wildly" does not make sense. That's what the summary basically said - I personally thought there were weird time effects being implied about the termination shock. It's just a crap use of a word in TFS that doesn't make sense.

Re:Worst. Write up. Ever.

[Stickney]

"...we don't consider the possibility that it has multiple distance values in a single moment of time."

"Nope. The solar winds overlap each other."

This would imply that yes, it _does_ have multiple distance values in a single moment of time.

Re:Worst. Write up. Ever.

[Anonymous Coward]

The writeup didn't bother me at all. But then, I *am* a scientist.

As well as a pompous twit, it seems.

The grandparent made a couple of reasonable points, which you missed.

Re:Worst. Write up. Ever.

[lawpoop]

"Nope. The solar winds overlap each other." This would imply that yes, it _does_ have multiple distance values in a single moment of time. Okay, so then what is this "termination shock" that Voyager is going to encounter? Isn't it encountering a termination shock every time it outpaces an overlapping solar wind front? What's this big deal about this termination shock?

Do the solar winds continue on forever, to the point where the first light from the sun now reaches out into the universe? Or is there a final outer boundary of solar winds, and wouldn't it therefore have a single 3-D distance value in time? The article doesn't seem to imply that Voyager is encountering various termination shocks from overlapping solar winds; it seems to say it's going outside of *all* solar winds.

Re:Worst. Write up. Ever.

[Anonymous Coward]

Don't you mean "sorry if it was too vague and lacking in important detail for you"?

Re:Worst. Write up. Ever.

[Anonymous Coward]

Scientist you may be. English major you are not.

It fluctuates in time because the sun's output fluctuates in time -- when the solar winds are stronger, the corresponding parts of the termination shock will be further away.

It does not fluctuate in time. It fluctuates with time. If it fluctuated in time, then the termination shock would be time traveling... I believe that would make it akin to the Nexus energy ribbon in Star Trek: Generations. It is not.

And you have some sort of problem with them describing the terminator shock as the boundary where the solar wind decelerates to the 'speed of sound'?

No... he has no problem with describing the termination shock as the boundary where the solar wind decelerates to the 'speed of sound.' What he has a problem with is redundancy. If I said, "the red ball is red. It is the color red, the red ball is," then you'd think I was pretty daft. Similarly, if I said, "the termination shock is the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed. At the termination shock the solar wind is decelerated to subsonic speed," then you'd think I was pretty daft, too. And that's exactly what happened.

Re:Worst. Write up. Ever.

[Remus Shepherd]

Ummmm....no, I don't agree. I could say, 'This data fluctuates', even though the data may be plotted on a spatial, not temporal axis.

I suppose you could make an argument that 'oscillates' or 'varies' would be better words, but I don't care that much about semantics.

Re:Worst. Write up. Ever.

[Remus Shepherd]

Okay, so then what is this "termination shock" that Voyager is going to encounter? Isn't it encountering a termination shock every time it outpaces an overlapping solar wind front?

Yes. The solar winds spread out like waves hitting a beach. Some of them get farther up on the beach than others. Voyager is hitting the first distinct wave, then will hit another.

The solar winds do not continue on forever -- they hit the termination shock and effectively stop. Voyager is going outside of all solar winds...but because they overlap, it's a bit imprecise to say when it'll get there.

What's the big deal? Uh...maybe nothing. It's a landmark, as far as I can tell, and nothing more.

Re:Worst. Write up. Ever.

[Anonymous Coward]

There will probably be lots of magnetic turbulence, although nobody really knows what to expect.

"Imperative! This is the Kobayashi Maru, nineteen periods... out of Altair Six. We have struck... a gravitic mine,... and have lost all power."

What, you were expecting a V'ger joke, maybe?

TFOAE

Re:Worst. Write up. Ever.

[Anonymous Coward]

It fluctuates in time because the sun's output fluctuates in time -- when the solar winds are stronger, the corresponding parts of the termination shock will be further away. So it fluctuates in both time and distance, and depends upon solar activity.

Perhaps a more accurate english wording would be "fluctuates OVER time." Consider this: "I can travel to destinations in time" versus "I can travel to destinations over time"... the first implies that I am a time traveler, the second states that i can travel from one location to another while a certain amount of time has elapsed. Using this common understanding of english (and that scientists have yet to accomplish time travel), i'd say that what you meant is that the sun's output fluctuates OVER time.

Re:Worst. Write up. Ever.

[lawpoop]

The solar winds do not continue on forever -- they hit the termination shock and effectively stop. Okay, so then can we simply say that there is only one measurement for the aggregate of solar wind, namely distance from the sun, and not worry about the time factor then?

Re:Worst. Write up. Ever.

[Anonymous Coward]

I *am* a scientist. If you were to plan a mission to investigate the termination shock what would that mission look like? I'll venture a guess and offer a collection of small, identical probes distributed uniformly in an expanding sphere, equipped with instruments to measure magnetic fields certainly, and very precise clocks. The probes would be low mass and accelerated to extreme velocity. The fleet would be launched within a minimal window to maximize the simultaneity of the data.

Re:Worst. Write up. Ever.

[Anonymous Coward]

How come a scientist doesn't know the meaning of the word "fluctuate"? It implies a variation over time, so to say that something "fluctuates in time" is nonsensical. It also implies an (irregular) oscillation. Are you saying that the terminator shock goes forward and backwards in time?

Re:Worst. Write up. Ever.

[Remus Shepherd]

Not really, because at different time periods there will be different strengths of solar wind, and some of those will reach farther out from the sun than others before they stop. Refer back to the 'waves on a beach' analogy again.

Re:Worst. Write up. Ever.

[lawpoop]

Not really, because at different time periods there will be different strengths of solar wind, and some of those will reach farther out from the sun than others before they stop. If I'm reading you right, you just argued my point. Originally, ancestor said that we need to measurements for the solar wind fluctuation, time and distance. I said that that was redundant; if a phenomena varies in distance, it therefore *must* vary in time, unless it's a counter-intuitive phenomena like quantum physics where a thing can have a superposition.

Refer back to the 'waves on a beach' analogy again. So what you're telling me is that when someone claims that the waves on a beach have a variable distance, those distances might be at the same moment in time?

Or, are you talking about the fact that there are multiple waves in the ocean, each with their own distance measure in the same moment of time? If that's the case, then what is this single "termination shock" that Voyager is passing? Isn't that equivalent to the furthest wave, or outermost reach of solar wind, which has a single distance value in a moment of time?

Why isn't the article talking about Voyager passing "termination shocks", one for each solar wind-front (or, each wave-swell in the ocean)? Isn't it talking about the final termination shock, at the end of solar wind emanations from the sun?

Or can the furthest wave have two distances at one time?

Maybe...

[Dan East]

Anyone else notice the related stories on the news site?
Nov. 6, 2003: Voyager Spacecraft Approaches Solar System's Final Frontier
Dec. 19, 2000: Most Distant Spacecraft May Reach Shock Zone Soon
May 25, 2005: Voyager Spacecraft Enters Solar System's Final Frontier

Besides the speculation, will we even know when the boundary is crossed? Do they expect data to indicate a transition, or do we even know if the instruments can detect such a thing?

Dan East

Re:Maybe...

[Galaga88]

Much like killing Rasputin, leaving the Solar System is apparently an ongoing process marked by significant milestones.

Re:Maybe...

[igotmybfg]

I didn't look up those articles, but it's plausible that some of them may be talking about Voyager I, which apparently passed termination shock in 2004. In any case, the termination shock's distance from the sun varies from 75 to 90 AU, depending on solar activity, which is why some are predicting that Voyager II will re-encounter the boundary in 2008 (and possibly beyond).

Re:Maybe...

[Ruie]

Besides the speculation, will we even know when the boundary is crossed? Do they expect data to indicate a transition, or do we even know if the instruments can detect such a thing?

Yes. They are still receiving telemetry from both spacecraft (Voyagers I and II) indicating plasma density, strength of magnetic fields and some other data that I forget.

Re:Maybe...

[ghostlibrary]

Yep, Voyager has approached the theoretical location of the termination shock often-- and each time, we get to revise our theories and have a better understanding of just how interesting our sun is. The joke among solar physicists is: "Where is the termination shock?" 'Just past Voyager.'

Re:Maybe...

[imnojezus]

Those articles all refer to Voyager 1. This one is about Voyager 2

Re:Maybe...

[januth]

If you look closely you'll see that those items refer to Voyager 1 not Voyager 2. Voyager 2 is on a different trajectory and will encounter the termination shock under a different set of circumstances.

Re:Maybe...

[Howitzer86]

It would be pretty neat if Voyager 2 suddenly popped up on the opposite side of the solar system. Then we'd have a new barrier to obsess over.

Re:Maybe...

[jellomizer]

My God the Catholic Church was right back in the 1600's. If that happends the republicans will be in charge for quite a while.

Re:Maybe...

[Mana Mana]

``Anyone else notice the related stories on the news site?
Nov. 6, 2003: Voyager Spacecraft Approaches Solar System's Final Frontier
Dec. 19, 2000: Most Distant Spacecraft May Reach Shock Zone Soon
May 25, 2005: Voyager Spacecraft Enters Solar System's Final Frontier''

Thank you! I thought the same. I originally read about this event / idea in the New York Times, back around mid 1990's, if not the early 1990s! I recollect the author described it as ~sort of like surf waves, rippling at the edge of the Solar System.~

FWIW, the Times had a contemporaneous series of front page articles on the Voyagers' discoveries! Saturn rings! new Jovian rings - travel through the rings - new moons! Uranus close ups! Fantastic stuff!

I read those articles mesmerized - to this day. Nothing since has captured the imagination; not PBS shows, e.g, Nova, etc.

When is someone going to do a fabulous book on these amazing stories, events, comprehensively.

A great documentary wouldn't hurt.

A creative Hollywood film on-topic?! Ah, yes, bereft-of-creativity-Hollywood.

Or, maybe there already is a fab book on the Voyagers' discoveries. At least a dig though the Times archives and a collection of same would be pleasurable to me, or anyone else.

Re:Maybe...

[tm2b]

Why would final irrefutable proof of the non-existence of God (cf. Douglas Adams) help the Republicans?

No

[InvisblePinkUnicorn]

No, it is not. It is the interstellar medium. Read: termination shock.

Re:No

[E 99]

No, it is not. It is the interstellar medium. Read: termination shock.

No it's not. The Wikipedia article is wrong were it implies that, and right where it says "At the termination shock, a standing shock wave, the solar wind falls below its speed of sound and becomes subsonic." Read Hydrolic Jump and Supercritical flow. The termination shock happens when the solar wind transitions from supercritical to subcritical, which is dependent on its own density, and its own wave speed (speed of sound), not the wave speed of the interstellar medium, which is much further out. While the wave speed of the interstellar medium is given by the article as 100km/s, the density and wave speed of the solar wind can't be expressed as a constant, as it is a function of distance from the sun and heliolatitude.

Re:No

[glaswegian]

Between the Sun and the shock, it is technically the Interplanetary medium

Re:No

[jtcm]

While the wave speed of the interstellar medium is given by the article as 100km/s

I read that in Wikipedia too, but it doesn't seem right. How is it possible that sounds travels so quickly through such a sparse medium? Here on Earth, the speed of in air is about 340 m/s. In water, where the molecules are closer together and can collide in more rapid succession, the speed is about 1500 m/s. In steel it's about 5000 m/s.

So how is it that compression waves travel almost 100 times faster through the sparse solar wind than they do through dense water?

Re:No

[eh2o]

The interplanetary medium is very low density but has a very high temperature of about 100000K. It is also pressurized by the solar wind. I find that temperatures in space are very non-intuitive... just remember that its a measure of random motion having average zero velocity -- it has nothing to do with "getting burned" per say.

Sound is a pressure-velocity wave but the velocity component is negligible for most cases (it also drops off as 1/r^2 whereas pressure drops off as 1/r, spherically, which is why the ear can still hear things using pressure sensing). Anyways, the wave propagates at a speed much faster than the particle drift velocity, and the speed of sound is determined by the joint temperature and density/pressure of the medium (and its elasticity and a few other things for various materials).

Something similar is essentially the case in a typical electronic circuit where the drift velocity of electrons is tiny (~ mm/sec) compared to the propagation of the voltage wave at near the speed of light.

Re:No

[eh2o]

Forgot to add; in the case of the voltage wave, the high propagation speed is due to the orbit velocity of the electron at the speed of light which, similar to a high temperature, has an average velocity of zero. So, it is a very, very small time before one electron pushes on the next (in particular for a metal where they all orbit in a sort of cloud).

So, you can think of the speed of sound as the amount of time before one particle hits another. Greater density or pressure decreases the distance between particles. Increasing temperature increases the rate that they travel across the gap, so also decreases the total propagation time.

Re:No

[bill_mcgonigle]

The Wikipedia article is wrong

So, fix it?

And what effect will this have?

[FirstTimeCaller]

I would expect that something called "Termination Shock" would have some dramatic effect on an object crossing it. Is this the case? It doesn't sound like it based on what I read. Sounds like a more appropriate name would be "Subsonic Solar Wind Boundary". But what fun is that?

Re:And what effect will this have?

[Dr. Eggman]

The mechanics definition of a shock is a sudden acceleration/deceleration. It's the sudden stop that kills you in the end of a fall; it's the pressure in the nuclear explosion that bowls over everything. As for termination, I suppose substituting 'Solar wind' would make it a bit clearer. But, termination tends to indicate an end to things, and placed with 'shock' sounds to indicate a boundary of sudden deceleration, where as 'solar wind shock' sounds more ambiguous, in an ironic sort of way.

Completely WRONG

[InvisblePinkUnicorn]

The speed of sound on earth is about 0.3 km/s. In the interstellar medium, it is tens of km/s.

Re:Completely WRONG

[calebt3]

Other posters are saying 100km/s at the termination shock.

Re:Completely WRONG

[ebolaZaireRules]

oops, yes, I was.

Though I _don't_ get how the speed of sound can be so fast in such a rarified medium, given that sound is nothing more than vibration.

finally a use for for seti telescopes:

[andreyvul]

they will be used to get data from voyager 2 on conditions at the edge of the solar system

however, a wobbly spacetime continuum means that voyager 2 must be running linux
because the wobbly spacetime is an infinite loop, only linux can escape it in 5 seconds
but time at the termination shock is slow enough that 5 seconds will be 2 years

Re:finally a use for for seti telescopes:

[StarfishOne]

Soo.. I guess the question on everyone's lips is: how does this wobbly spacetime affect the BogoMips of an unladen Linux machine?!?

Re:finally a use for for seti telescopes:

[jacksonj04]

The wibbly wobbly timey wimey stuff is getting involved in Voyager now? I thought they weren't allowed to nick space-time continuums from other series!

Re:finally a use for for seti telescopes:

[geminidomino]

KDE or Gnome?

Bingo

[Prefader]

The speed of sound isn't a constant, and space isn't a total vacuum.

Over The Horizon Stuff

[blueZhift]

This is pure, over the horizon, is the earth round or flat, kind of stuff. While no one is expecting anything extraordinary, you never really know until you go and look.

Beyond the Beyond

[john.q.avatar]

Here is a funny cartoon about the Voyager Termination Shock: http://www.unripe.com/pages/cartoon%2067%20termination%20shock.html

100km/s? Bloody unlikely

[Viol8]

The speed of sound goes DOWN with reducing density , not up. Theres no way the speed in an almost vacuum could be hundreds of times higher than at sea level. Even in rock it only manages a few km/s. Perhaps the author meant 100m/s but even then I'd be suspicious since in intersteller space the gas molecules rarely touch each other so theres no physical way for sound to propagate anyway.

Re:100km/s? Bloody unlikely

[imsabbel]

Plasma, meet speed of sound.
"Why are you so high, for my low density?"
"Because you are plasma, and no stupid ideal gas, slowpoke!"

Re:100km/s? Bloody unlikely

[Anonymous Coward]

The speed of sound goes DOWN with reducing density , not up.

No, it goes up.

c = ( C / p ) ^ -2

where
        C is a coefficient of stiffness
        p is the density

Re:100km/s? Bloody unlikely

[flibbajobber]

(C/p)^(1/2) actually, not (C/p)^(-2)

Re:100km/s? Bloody unlikely

[Viol8]

>No, it goes up.

Sorry you're wrong. Look up the speeds of sound in various mediums such as air, water and rock if you have any doubts.

It varies

[InvisblePinkUnicorn]

"Other posters are saying..."

That's only because it's what Wikipedia says. The speed of sound in the interstellar medium depends on the density of the medium, which varies, so it's different everywhere.

avoid repetitive redundancy

[Anonymous Coward]

...will cross the termination shock, the spherical shell
    around the solar system that marks where the solar wind
    slows down to subsonic speed. At the termination shock,
    located at 7-8.5 billion miles from the sun, the solar
    wind is decelerated to less than the speed of sound.

repeat repeat after after me me

My solar system, let me show it to you...

[rucs_hack]

Want to see the actual orbital trajectories of the Voyager probes for yourself in 3d type of thing? Because you can, if you use my nBody modeling software.

If you go here:

http://code.google.com/p/nmod/downloads/list

and get the windows installer or linux source for my nbody modeling kit, and then download this:

http://www.politespider.com/nbo/time_series.zip

And unzip it to save you the bother of having to actually generate your own time series (3d time series model of the solar system), which can take a while. You can then watch both Voyager probes follow their orbits (with 24th august 2006 as their starting date), for 20,000 days of travel time.

This isn't a program with a scrummy easy interface I'm afraid, the viewer is console opengl. But there are instructions here:

http://code.google.com/p/nmod/wiki/nbview

And it's not too hard once you get the hang of it.

The orbits do not take termination shock into account, this is pure Newtonian motion. The dataset for the solar system has taken months to put together. It's incomplete, It only has our moon (zoom in for ages with Earth centred and you'll see it), the others have been tricky to get right.

Re:My solar system, let me show it to you...

[Anonymous Coward]

This is awesome. Thank you. one of those rare times slashdot satisfies

Re:My solar system, let me show it to you...

[rucs_hack]

This is awesome. Thank you. one of those rare times slashdot satisfies

Your welcome, feel free to add to the project, it's just little old me for now.

There's nothing there...

[Myria]

Once it gets there and crossing is a non-event, we will see that there is nothing of interest out there. Voyager 2 is just crossing into vast, bleak nothingness.

Re:There's nothing there...

[gstoddart]

Once it gets there and crossing is a non-event, we will see that there is nothing of interest out there. Voyager 2 is just crossing into vast, bleak nothingness.

Even if nothing cool or dramatic happens, this isn't a non-event.

This will be the furthest we've ever flung an object from our planet. The milestone may be more symbolic than anything, but this is actually rather impressive.

Cheers

Re:There's nothing there...

[Anonymous Coward]

Wow.
I thought about this statement for a while and had this brief but intense sadness for that little twist of metal. Some David Bowie lyrics came to mind as I pictured that inky void, that abyss approaching. Bleak, indeed.

Re:There's nothing there...

[Suicyco]

Voyager 1 is the furthest human object.

Here is a nice link and a graphic of what is still being explored: http://voyager.jpl.nasa.gov/mission/interstellar.html

Re:There's nothing there...

[gstoddart]

Voyager 1 is the furthest human object.

Here is a nice link and a graphic of what is still being explored

Ah, thanks for the correction and the link. I was thinking V2 was going to cross the boundary first. As you say, V1 has already done so and is the furthest human object we've made.

Cheers

Re:Remind me again / Jango Fett

[Anonymous Coward]

He proved that sound is possible in that episode whateverthefuxit when he attacked Obi-Wan in the mini spacecraft piloted by R4. Jesus! I know too much(or don't if you know what I mean), LOL!

hrm...

[spottedkangaroo]

What is the speed of sound in a vacuum? Kinda existential...

Re:hrm...

[StarfishOne]

As long as I don't ever have to hear the sound of a space probe that is trying to communicate with a certain type of whale again, the speed is not really interesting to me anymore. :p ^_^

The edge of...

[infodude]

It's going to reach the edge of the simulation, where it'll get rendered in lower resolution.

Re:The edge of...

[MR.Mic]

No, it will just get baked into the skybox. Much less of a performance drain that way.

next step: interstellar probe

[ceroklis]

I am looking forward to the interstellar probe mission, which is specifically designed to explore the interstellar medium.

Unfortunately it will probably not happen in my lifetime, unless we stop putting in charge of the budget people who think that a talk between a teacher in LEO and school-children on earth is more "inspiring" than fundamental research.

We already are quite accurate

[junglee_iitk]

What you are refering to is Voyager 1. TFA is about Voyager 2. They are two different vehicles.

<wikipedia href="Heliosphere">
Evidence presented at a meeting of the American Geophysical Union in May 2005 by Dr. Ed Stone suggests that the Voyager 1 spacecraft passed termination shock in December 2004, when it was about 94 AU from the sun, by virtue of the change in magnetic readings taken from the craft. In contrast, Voyager 2 began detecting returning particles when it was only 76 AU from the sun, in May 2006. This implies that the heliosphere may be irregularly shaped, bulging outwards in the sun's northern hemisphere and pushed inward in the south.
</wikipedia>

Re:We already are quite accurate

[Tragek]

See. Now that's a tag syntax HTML 5 needs, none of this silly stuff.

Re:We already are quite accurate

[Tragek]

... like etc. (DAMN HTML ENTITIES)

That's Garbage

[Crazy Taco]

The speed of sound in the interstellar medium is much higher than it is on earth. In case you didn't know, space is not empty. Vacuum is, but space isn't.

That's garbage. Space is not a total vacuum, it's true. However, the density of particles of matter in space is, for the most part, so low that space can be treated as a vacuum. It's like rounding 0.1xE-25 to just 0.

And as for the whole thing about sound travelling faster in space, you just made that up. Light (and other electromagnetic phenomena) do travel faster in a vacuum like space (perhaps you've confused the two). Sound, however, is caused waves of physical compression. In other words, one particle bumps into the next, which bumps into the next, and so on. Sound travels faster and farther through more solid materials. It has a certain speed and a certain distance it will travel in air, a faster speed and greater distance in water, and an even faster speed and greater distance through concrete. It has no speed or distance at all in space, because what little matter there is isn't close enough to touch the next peice of matter, and you can't set up the compression wave.

Re:That's Garbage

[AHumbleOpinion]

0.1xE-25

I apologize but the nerd in me has to ask, why not 1.0E-26? Is it some kind of psychological thing that makes the number look significantly smaller, like pricing at (x-1).99 rather than x.00?

To other readers, yes I know that (x-1).99 != x.00. Notice the word "significantly" and note the context of psychology of pricing.

Re:That's Garbage

[kebes]

You're making a few mistakes...

Space is not a total vacuum, it's true. However, the density of particles of matter in space is, for the most part, so low that space can be treated as a vacuum. It's like rounding 0.1xE-25 to just 0. Rounding and approximations cannot be treated as glibly as you are doing. Approximating outer space as a perfect vacuum is a reasonable approximation for many calculations, but not all. For instance when calculating the properties of light traveling through outer space over short distances (e.g. less than a light year) saying it is a "perfect vacuum" is fine. But when doing calculations over long distances (billions of light years), the thin interstellar medium does indeed induce absorption and polarization effects that must be considered.

So you cannot always assume that "near vacuum" and "perfect vacuum" are the same thing. In the case of solar wind interacting with the interstellar medium, you can't approximate either as having zero density: to do so would ignore some very real physics that occurs when the pressure of the high-velocity solar wind impinges on the nominally static interstellar medium.

And as for the whole thing about sound travelling faster in space, you just made that up. Every material (even low-density materials like the interstellar medium) have a "speed of sound." The interstellar medium is no different. It has a "speed of sound" on the order of 10 km/s to 100 km/s (by comparison the speed of sound for air on Earth is 0.3 km/s).

Sound travels faster and farther through more solid materials. You're being imprecise by saying that sound travels faster in more "solid" materials. The equation is:
v = sqrt( C/d )
where v is the speed of sound, C is the coefficient of stiffness, and d is the density. So, actually, more dense materials have a lower speed of sound (all other things being equal). The reason that liquids and solids have higher speed of sound is not because they are dense, but rather because they have strong cohesive forces binding the constituent atoms/molecules together (that's why they are condensed into a solid or liquid, after all). These strong forces lead to a very high coefficient of stiffness, compared to a gas (more than enough to offset the higher density).

For something like the interstellar medium, the stiffness is quite low, but the density is exceedingly low, which produces a correspondingly large speed of sound.

Sound, however, is caused waves of physical compression. In other words, one particle bumps into the next, which bumps into the next, and so on. You're quite right. However nothing prevents compression waves from traveling in low-density materials. The atoms of the material are free to fly large distances, and they will indeed statistically bump into each other, transfer momentum, and so on. This collective motion will indeed be compression waves. Of course you will not be able to set up very large-amplitude compression waves using, e.g. your vocal cords in such a low-density medium... but the high-speed collision of the solar wind with the interstellar medium will most certainly lead to all kinds of expanding pressure waves, whose behavior is dependent on the local speed of sound.

These pressure-wave effects are of course difficult to measure in such a low-density medium, but they are certainly real.

Re:That's Garbage

[AndersOSU]

It's not garbage. The density of matter in space is important, and speed of sound is applicable.

Think of it this way, if your sitting in the next cubicle over and I whisper something and you are unable to hear it, does that mean that the speed of sound doesn't exist, or simply that the amplitude of the signal was too small? Similarly, in order to transmit sound in space I'd need some serious lungs. More to the point the speed of sound is a critical parameter when examining how two flows (such as the solar wind and the interstellar medium) interact. Simply put if the speed of sound in the interstellar medium were undefined it would not interact with the solar wind, and there wouldn't be a termination shock at all. Every particle of the solar wind would not interact with any particles of the interstellar medium.

It's been a while since I've done any fluid dynamics, so some of the details may not be precisely right, and I am not knowledgeable enough on rarefied systems to comment on why the speed of sound is so high in the interstellar medium, but suffice to say that many things behave in counter-intuitive ways for rarefied systems.

Re:That's Garbage

[NeilTheStupidHead]

0.1xE-25

I apologize but the nerd in me has to ask, why not 1.0E-26? Is it some kind of psychological thing that makes the number look significantly smaller, like pricing at (x-1).99 rather than x.00?

To other readers, yes I know that (x-1).99 != x.00. Notice the word "significantly" and note the context of psychology of pricing. The engineer in me asks: why not 0.01E-24 or 10E-27? Then we'd have 0.01 yocto-whatevers or have to invent a prefix for 10^-27 cause I couldn't find one. Wait, does that mean I get to name it?

Re:That's Garbage

[Anonymous Coward]

Actually you tend to describe both the interplanetary medium, and the interplanetary medium by the same argument, as entirely collisionless for the most part. The mean-free path of particles in the solar wind is something like a few astronomical units.

The exchange of momentum actually comes about through the interactions between the magnetic fields permeating these two plasmas (as they are both almost perfectly ionised - protons and neutrons for most part). As such, all of this stuff is termed, in a wonderfully concise way, "Magnetohydrodynamics".

Re:That's Garbage

[mOdQuArK!]

The engineer in me asks: why not 0.01E-24 or 10E-27?

It's customary to use the # of digits before the "e" as an easy way to indicate the precision of the value. Engineering notation isn't a canonical-enough form to do that consistently.

The rest of your response confused me too much to come up with a coherent comment.

...and then...

[Sebastopol]

...it will land with a "kerPLUNK!" into a half full goblet of mead at the foot of Zeus.

Re:...and then...

[sharkey]

No, it's half empty!

A Few Things

[BlackGriffen]

As another reply already noted, this is the interstellar medium, which should be a good deal dense than the space between galaxies and galaxy clusters.

Next, how does sound transmit? Well, sound is a density/pressure wave, right? All I need is for the free particles to be interacting somehow to set one up. Turns out, the interstellar medium isn't a gas like you're used to thinking of, it's a plasma. The important point here being that because the electrons are not bound to the atoms, the effective "size" of the atoms goes up (that is, the disntance over which they interact with neighboring atoms). Thus you should be able to get sound waves more easily than you would suspect from a regular gas that is that sparse.

The speed of sound

[SCHecklerX]

what?

The speed of sound is different depending on the medium. The speed of sound where? (I didn't RTFA, just pointing out the lameness of the summary). Usually, when you talk about the speed of sound, it is relative to the density where you are observing your speed. So in space, having the solar wind be less than that (~0), does it then bounce back? :-)

Re:The speed of sound

[4D6963]

The speed of sound is different depending on the medium. The speed of sound where?

Indeed, that was quite ambiguous in the summary. Whereas people here keep talking about what the speed of sound in plasma/intersolar whatever is, I think we need not to look any further the not so science-savvy author trying to give us an estimate of the speed he's talking about in layman terms, that is, the speed of sound at the sea level.

Obvious question...

[pottymouth]

Ehhhh, how fast does sound travel in space again.....?

Why don't we do this more often?

[Crazy Taco]

Science at it's very purest form, simply going and observing something nobody has actually seen before.

I agree that this is a very pure and useful form of science. However, what I don't understand is why we don't do this more often. Why haven't we been sending out a probe every year, or at least every five years, upgraded with the best propulsion systems and scientific instruments we can put on it? These two probes were launched 30 years ago, and while they still work, technology improved a lot over the decades. If it takes 30 years to get to the termination shock, it seems like they took an awfully big risk sending just two probes and then sitting tight. If something went wrong or failed, you have just one probe left, or maybe none if it was an issue common to the two of them. And then you have to wait 30 years to get back to where you were. In addition, science usually likes many repeated observations of phenomena more than just a few, and repeatedly launching probes in different directions would have helped establish even more reliablity for all data returned.

I just don't understand why we don't do this more often. I would have to think we could build a better, sturdier probe with a faster propulsion system, longer lasting power sources and far more powerful scientific devices. Unless perhaps we have launched another probe that will eventually have this mission (but maybe is doing something else on the way for now), I just don't understand why we don't do this again.

Re:Why don't we do this more often?

[Tango42]

Because few governments expect to still be in power in 30 year's time, so what's the point? Cynical? Me? Never... ;)

It's worth pointing out that the primary missions of the Voyager probes were to explore the outer planets, which they did with great success many years ago (and we have sent more probes since). The fact that they are still active now and sending back useful information about the termination shock is just a bonus, so what you say about only sending two being a risk isn't really valid.

Re:Why don't we do this more often?

[Diakoneo]

We can't do this _every_ year because the reason the Voyagers made it out so far was gravity assist.
But I agree, I'd like to see NASA funding going to a lot of smaller projects like this than one behemoth one.

Re:Why don't we do this more often?

[Anonymous Coward]

The Voyager probes weren't launched with the goal of exploring the termination shock and the outer boundaries of the solar system. If they had, the instrument packages would have been different. The data currently being returned by these probes is "bonus" science, an unexpected treat, as few people thought they would last as long as they have.

I'm sure someday in the future, we will launch interstellar probes with the express purpose of exploring the interstellar environment. The propulsion systems will be different from Voyager and the instrument payload will be different from Voyager.

Some but not much

[WindBourne]

The nukes are way down on power, so most of the instrumentation is not running. We will get some though.

It would be interesting to see a new voyager sent out. In particular, obtain bigger nukes, use bigger rockets (perhaps the ares IV/V), and finally, add ION drives. I do not know how long it would take to reach the edge again, but if done right, it could reach there in a fraction of the time and obtain more useful data. If nothing else, this would be the kind of science that Russia or China should consider doing. For some odd reason USSR/Russia really does not do that much with long term Science missions. They have never sent anything real deep. For the most part, they appear to be only interested in places that we can send mankind to.

Re:Some but not much

[grep_rocks]

Or we could work on nuclear propulsion and get there in no time... you can build an 8M ton ship that can go 10% the speed of light using 1960s technology... http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) of course it drops H-bombs out the back onto a metal plate so it isn't super eco-friendly...

Re:Some but not much

[jo7hs2]

I think it is rather obvious why China and Russia don't focus on long-term scientific missions. There is no huge whiz-bang factor that you can use as either a competitive comparison to outside nations, or as a way of showing the power of the state. While politicians in America have to placate/distract the people with the occasional metaphorical fireworks show, there is no need to keep the people in line by showing the power of the state. Stop and think back to the Sojourner mission. The first images came back during a holiday, so people were able to view them, but do you remember how many people sat in front of the TV to see them rather than sit out on the deck with a beer? Had there been people on that mission, I assure you it would have been watched in earnest.

Re:Some but not much

[david.given]

It would be interesting to see a new voyager sent out. In particular, obtain bigger nukes, use bigger rockets (perhaps the ares IV/V), and finally, add ION drives.

Do you mean like New Horizons, which recently passed Jupiter (and took some stunning pictures, too). It's due to fly by Pluto and Charon in 2015, and enter the Kuiper belt shortly after.

Okay, it's not a very good comparison; New Horizons didn't get the gravity boost of the Voyagers and so isn't going as fast; and it doesn't have an engine, so is coasting all the way. An ion drive would have improved the flight time. But it is powered by an RTG, and it has reached solar escape velocity. That makes it one of the only eight man-made objects to do so.

Re:Some but not much

[TooMuchToDo]

Not much environment in space to protect guvn'ar. Call me when we have warp drives and we're worried about tearing up space-time.

Re:Some but not much

[markov_chain]

If you're going to add ion drives, you should go all out and also throw in the Mark IV computer, level 4 shields, and neutron beams!

Re:Some but not much

[grep_rocks]

you have to launch the ship from earth - unless you can build a 8M ton ship in space... the good new is H-bombs (fusion) have less fall out unit energy than fission nukes

Re:Some but not much

[griffman99h]

Actually to be fair your comparison is quite valid. I only know this cause I looked it up before.

NH went by Jupiter FOR a gravity assist. It IS utilizing an Ion drive. and is now the fastest moving man made object in space.... at 46,975mph.

Jupiter gravity assist

New Horizons received a Jupiter gravity assist with a closest approach at 5:43:40 UTC (12:43:40am EST) on February 28, 2007. It passed through the Jupiter system at 21 km/s (46,975 mph) relative to Jupiter (23 km/s (51,449 mph) relative to the Sun). New Horizons was the first probe launched directly towards Jupiter since the Ulysses probe in 1990.

The flyby increased New Horizons' speed away from the Sun by nearly 4 km/s (8,947 mph), putting the spacecraft on a faster trajectory to Pluto, about 2.5 degrees out of the plane of the Earth's orbit (the "ecliptic").

as for Voyager 2..... well the data USED to be in wikipedia, but its missing right now, what it does say is that its going slower than Voyager 1 which is traveling at 38,400mph. making it 8,000mph slower that New Horizons.....

As of November 2005, the spacecraft was traveling at a speed of 17.2 kilometers per second relative to the sun (3.6 AU per year or 38,400 miles per hour), 10% faster than Voyager 2. Accurate information concerning its location can be found in this NASA paper with heliocentric coordinates extrapolated up to 2015 of both probes.

do some research before selling yourself short ;P

Re:Some but not much

[david.given]

as for Voyager 2..... well the data USED to be in wikipedia, but its missing right now, what it does say is that its going slower than Voyager 1 which is traveling at 38,400mph. making it 8,000mph slower that New Horizons.....

Yeah, but Voyager 1 is a hell of a lot further out of the Sun's gravity well than New Horizons. NH has to climb out of the well, and is going to slow down, which means that NH will never catch Voyager. I gather the relevant phrase is 'hyperbolic excess velocity'...

I'll take a crack at it.

[Khyber]

While it's not as DENSE, since sound is just energy, the atoms carry the energy (and the vacuum between transmits the energy) but there's not enough atoms to really stimulate your eardrum. That is, provided you could take your helmet off in the relative vacuum of space and survive, there's just simply not enough mass present to allow stimulation of our aural system.

Unless I'm mistaken

[porkchop_d_clown]

The Pioneers were dead when the left the solar system. The Voyagers are still sending data.

Re:Unless I'm mistaken

[Captain Nitpick]

The Pioneers were dead when the left the solar system.

That depends on how one defines "left the solar system". Both Pioneer 10 and 11 were still transmitting (and having said transmissions recieved) well past the orbit of Pluto.

Re:Unless I'm mistaken

[david.given]

...and you can get the data sets here. Admittedly, there's not a lot you can do with it if you're not a highly specialised astronomer and plasma physicist, but it's cool that it's available, nevertheless.

Re:Unless I'm mistaken

[porkchop_d_clown]

I'm pretty sure that the termination shock wave is considered the edge of the solar system. After all, Pluto is merely the closest of dozens (estimated) of similar bodies.

Re:Unless I'm mistaken

[Captain Nitpick]

I'm pretty sure that the termination shock wave is considered the edge of the solar system. After all, Pluto is merely the closest of dozens (estimated) of similar bodies.

At the time the probes went past its orbit, Pluto was considered the outermost of a handful of planets.

There's several different possible meanings for "edge of the solar system". The least-distant definition is the orbit of the outermost planet in the system (30 AU). Then we've got the outer edge of the Kuiper belt (~55 AU), the termination shock (75-95 AU), the heliopause (distance depends on direction, maximum probably 200 AU), and the outer bound of the Oort cloud (distance unknown, but possibly as much as several light-years).

The heliopause, which marks the boundary between the heliosphere and the interstellar medium, makes for a better "edge of the solar system" than the termination shock, which is just a velocity transition within the heliosphere. No probe has passed the heliopause.

The last contact with Pioneer 10 was at 80.22 AU. Voyager 1 data suggests the termination shock was at 94 AU. Voyager 2 data suggests it was at 76 AU.

Whether the Pioneer probes were dead before reaching the edge of the solar system depends on the definition chosen. By some definitions, it's not even a meaningful statement, as they haven't gotten to those boundaries yet. They may not have even reached the termination shock in their neck of the woods.

Re:Unless I'm mistaken

[rmckeethen]

Actually, Pioneer 10 is likely still transmitting data. At last contact, the spacecraft was apparently still functional. The problem is that Pioneer 10 is now so far away, and the signal so week due to depletion of the RTG power source, that none of NASA's current Deep Space Network receivers can pick-up the transmission above the background noise. However, given a large enough receiver, and the appropriate gear to detect extremely week signals, who knows -- it may be that Pioneer 10 is still out there trying to call home.

If you're interested, this NASA page provides a few details on the last reported contact with Pioneer 10.

Congrats to Humanity

[Jtheletter]

We will soon be intergalactic litterbugs.

Re:Congrats to Humanity

[808140]

You mean interstellar, right? Voyager 2 won't be intergalactic for a long, long time...

Re:Congrats to Humanity

[KiloByte]

Not ever, actually. It would need to go pretty fast -- the escape velocity needed to escape our galaxy from the vicinity of the Solar system is around 1000km/s.

We have ever launched 5 spacecraft going fast enough to escape out of the Solar system, at mere 11-ish km/s at the Earth orbit ("-ish" because we cheat a bit using gravitational slingshots).

I got jokes

[drachenstern]

Whats that? To visit space, I don't have to fly on VirginSpaceLines, I can just goto SoCal? (if you don't get the joke, leave the site now)

Alternate humorous statement:

So can we send some of the excess "stars" we have here into space to help fill that interstellar void? I think we have way more than we need now. (Bonus points are credited for this option too, as many in SoCal are just waiting for the spaceship to take them away anyways)

Re:Remind me again - plasma sound waves

[Anonymous Coward]

The 'speed of sound' referred to in the solar wind is the speed of 'Ion Acoustic Waves' in a neutral plasma. These waves exhibit the same sorts of behavior as typical pressure sound that we experience on a daily basis - namely that the speed of these waves is a constant. (\omega/k = v_s). In the case of the ion waves, a cloud of dissociated charges (ionized atoms and free electrons) exert direct electrostatic forces and pressures as the restoring force which allows the wave to propagate. Whereas sound that we hear is a fluid effect which propagates owing to conventional gas pressure. http://en.wikipedia.org/wiki/Ion_acoustic_wave

AC Nazi-esque-ness

[Anonymous Coward]

I suggest should be

I submit

The boundary of the termination shock is [...] wobbly, fluctuating in both time and distance from the sun Are you SURE that it fluctuates in time from the sun, or do you actually mean that it fluctuates (only) in distance from the sun? No, it must fluctuate in time as well, I read it on the intartubules just next week.

haha, I try and go all AC, and I get this

Slow Down Cowboy!

Slashdot requires you to wait between each successful posting of a comment to allow everyone a fair chance at posting a comment.

It's been n minutes since you last successfully posted a comment

Price Fixing

[camperdave]

I have heard that some stores use the cents part of the price to indicate a category of pricing. For example, $x.99 is regularly priced, $x.98 is sale priced, $x.97 is clearance priced, etc.

Re:Price Fixing

[Bob-taro]

I have heard that some stores use the cents part of the price to indicate a category of pricing. For example, $x.99 is regularly priced, $x.98 is sale priced, $x.97 is clearance priced, etc.

Today only! Closeout prices! Everything in the store is 3 cents off! That's right, 3 cents off! That's lower than sale price! Even lower than clearance sale price! Don't miss this amazing opportunity!

Re:Price Fixing

[lazy_playboy]

and *.99 price forces the cashier to open the til, I've heard, rather than just to pocket the round £10 (or dollars or whatever)

Re:Price Fixing

[Kelson]

and *.99 price forces the cashier to open the til, I've heard, rather than just to pocket the round £10 (or dollars or whatever)

Depends on whether sales tax/VAT are included in the price. Here in the US (or at least in California), sales tax is rarely included in the advertised price. So a round $10.00 on a price tag or menu is still going to end up as a (for example) $10.78 transaction. Under those circumstances, setting the price at $9.99 doesn't make a difference in whether the clerk needs to make change or not.

Re:Price Fixing

[Josh Booth]

Well, not quite three cents, but when I worked at target, iPods would go on sale for literally 99 cents off just so they had something to put in the circular. Just simply moronic.

Make your own termination shock.

[serviscope_minor]

A termination shock/shockwave/bore/hydraulic jump occurs when the bulk speed of a fluid drops below the wave propagation speed.

Run a tap in to a flat sink (like a kitchen sink) and you see a circular pattern (if the sink is flat) some distance from around where the water hits the sink. The pattern should have shallow fast moving awater close to where the jst hist the sink, and deeper slower water on the other side of the circle.

The "jump" where the water goes from fast to slow is the same kind of object as a termination shock. For extra fun, stick an object in the slow water, and see how waves propagate ahead of it (against the flow). Then see how it doesn't happen in the fast water.

Re:Make your own termination shock.

[Anonymous Coward]

You just got that all off of wikipedia, didn't you, Mr. Expert?

Re:Make your own termination shock.

[serviscope_minor]

No, I'm an engineer. I learned about hydraulic jumps and shockwaves years ago when studying mechanical engineering as an undergraduate. It was one of thouse courses which covered hydraulic jumps, broad crested weirs, venturi flumes, v-notches and probably others. My lecturer pointed out the example about a tap in the sink.

I just looked, and the wikipedia page is, as usual, excellent.

Re:Make your own termination shock.

[rastoboy29]

What a terrific explanation.  Thanks!

Cool

[twmcneil]

I can't wait to see the pictures of the Restaurant.

Speed of sound in vacuum

[flyingfsck]

So what is the relevance of the speed of sound in a near perfect vacuum? Not to mention the idea of a shock wave in nothing.

Re:Speed of sound in vacuum

[glaswegian]

Interplanetary space is not a void. There is matter, just its density is so low that not even our best laboratory "voids" can match its low density. But there is "stuff" so a sound speed is definable and shocks certainly do happen.

OMG NOOOOOO!

[belligerent0001]

Hey, what if this imaginary fluctuating boundary is actually like the film of a soap bubble...what if Voyager Deuce bursts our bubble?

I can see it now.

[Anonymous Coward]

/. 2072 Headline: Citadel to Reach System Shock

Incidentally,

[jagdish]

NASA has outlined its plans for a Mars mission. A 30 month mission with around 7 months traveling time and 16 months on Mars is the idea. They hope to accomplish this by an advanced cryogenic fuel propulsion system. The space ship is supposed to weigh 400,000 kgs.

They would need to be well-versed in the maintenance and repair of equipment and perhaps even able to manufacture new parts.

I suppose we should send Macgyver up there.

hmm..

[Rub1cnt]

So why is Voyager 1 continuously beaming back: "Remember, aperture science take your daughter to work day is the perfect time to have her tested.." and "The Cake Is A LIE!" And When does Voyager 6 launch? :)

Welcome back!

[Anonymous Coward]

I, for one, plan to welcome our returning creator-seeking V-Ger overlord

Re:Welcome back!

[Anonymous Coward]

You know, I never could understand why Vger - an artificial intelligence with almost limitless power - never managed to figure out how to clean some fucking dirt off a metal panel in order to know the proper spelling of it's own name.

The interstellar medium has huge effects on light

[glaswegian]

But when doing calculations over long distances (billions of light years), the thin interstellar medium does indeed induce absorption and polarization effects that must be considered. The effects happen on much smaller scales than this, and will depend on the density of matter that the light crosses. You can simply look at an optical image towards the centre of our Galaxy. It is only ~25000 light years away and has a huge concentration of stars. It should be a blazing ball of light but it is obscured by a dark "shadow".

This is the effect of minute "dust" particles permeating space and absorbing/deflecting light. The effect is less for longer wavelengths which is why we can get a better view of the Galactic centre in the infrared.

When will 'then' be 'now'?

[framauro13]

So at this point will Voyager 2 hit ludicrous speed or plaid?

How do we know?

[slapout]

How do we know that solar winds slow down to sub sonic speeds if Voyager is the first thing from Earth to reach this point.

Vger

[Anonymous Coward]

When does Vger come back?

Re:Its welcome back

[Tetsujin]

You know, I never could understand why Vger - an artificial intelligence with almost limitless power - never managed to figure out how to clean some fucking dirt off a metal panel in order to know the proper spelling of it's own name. Well, there was a lot of dirt there. It took some elbow grease to get it off. And, limitless power or no, V'Ger didn't have any elbows.

Oh, and it's its its its its its its its ITS ITS ITS!!!

Infinite Loop??

[Anonymous Coward]

they will be used to get data from voyager 2 on conditions at the edge of the solar system

however, a wobbly spacetime continuum means that voyager 2 must be running linux
because the wobbly spacetime is an infinite loop , only linux can escape it in 5 seconds
but time at the termination shock is slow enough that 5 seconds will be 2 years

Sounds to me like they're running something other than Linux...

Speed of sound in the interstellar medium?

[jgoemat]

Is that the right terminology? What is the "interstellar medium"? Surely it's not stationary with regards to the sun or earth, is it?

Oh that Voyager!

[Midnight Thunder]

When I first read the headline I thought that they had brought out another Star Trek series and shocked their fans by early termination.

Thanks

[LanMan04]

Thank you for that extremely enlightening explanation. Patient with the OP and well thought out.

Thanks again.

Imagining many little scientists

[ravensee]

Peeing their pants after observing a blip on their sensors that this in fact has happened.

Is there a prize for worst written summary?

[Tired and Emotional]

This summary has to be a finalist.

First it tells us twice that the solar wind falls below the speed of sound at the termination shock. Surely saying this once would have sufficed. Even in Montreal where they like to tell you everything twice they at least do it once in English and then again in French.

Then it goes on to claim that the terminator wobbles both in time and space. What the heck does that mean? How can something wobble in time and space?

Re:Is there a prize for worst written summary?

[rholland356]

Just what is the significance of the speed of sound as a measure for deciding the boundary of the termination shock? How 1940's is that? The speed of sound really meant something back then.

If you are going to choose an arbitrary measure, at least choose one that doesn't have you thinking, "In space no one can hear you scream."

Exactly!

[FatSean]

Not many places in the US interest me. I've seen the natural beauty, but I prefer bumming around cities. US cities....meh...NYC, Chicago, Boston, San Francisco are all interesting but the majority of 'vacation destinations' in the US just don't interest me. I'd rather spend my dough hanging about Rome for 2 weeks than spend 6 weeks touring the US.

I went through my own termination shock...

[ashitaka]

But then I got a new job.

(Hanging my head in shame at not being able to post anything more insightful than this as everyone else already has.)

The Truman Show

[nilbog]

I keep imagining that scene in the Truman Show where Truman's boat hits a wall painted like the sky.

My theory is that the terminal shock is just a big wall painted with stars and galaxies all over it. We're going to find out our solar system is just inclosed in a big ball and that we're part of some cosmic reality show.

Umm - question?

[the_Bionic_lemming]

It's a vacuum out there. What slowed the solar wind down?

Forgive me, I'm not a science major.

Re:Umm - question?

[aadvancedGIR]

pressure of the interstellar gas. Just remember that vacuum is a very relative concept.

Re:Umm - question?

[the_Bionic_lemming]

But if the pressure stopped, and there was nothing to slow it down - what slowed it down?

The MESSAGE

[zazenation]

The speed of sound in the interstellar medium is much higher than it is on earth. In case you didn't know, space is not empty. Vacuum is, but space isn't. The speed of sound doesn't matter in the medium.

"The medium IS the message"

According to wikipedia, they arlreaady did!

[Bill, Shooter of Bul]

From the wiki article linked in the summary

", it was announced that Voyager 1 had crossed the termination shock and entered the heliosheath in December 2004, at a distance of 85 AU. In contrast, Voyager II began detecting returning particles suggesting it was entering the termination shock when it was only 76 AU from the sun, in May 2006. This implies that the heliosphere may be irregularly shaped, bulging outwards in the sun's northern hemisphere and pushed inward in the south. "

So .. Whats up with that?

No Way, Jose!

[zazenation]

Exactly zero. That is BS.
I hear the USS Enterprise make power-up warp sounds and Darth Vader's Tigh fighters screech across interstellar space with Doppler pitch shifts all the time while in a vacuum. What about that cool rumbling power of Borg cubes?
Also, what about the cataclysmic explosion one hears when a star supernovas with a small dose of trilithium? How could you hear that if sound traveled at zero ft/sec?

Re:No Way, Jose!

[locster]

I agree. The fact of the matter is that without sound space is boring and that's why we don't have a flourishing space industry. Thus, one of the biggest scientific problems facing humanity today is how to get cool sound effects to travel through the vaccum of space. Until that one is solved no-one is interested in space. FACT! ;)

Snow globe

[hound3000]

And then bounces back off the glass of some cosmic snow globe.

Feeding the septic troll, I know, but....

[N Monkey]

I know I'm feeding the troll but...

Fucking Europeans man...Sometimes I hope a 2nd bubonic plague hits.

Assuming you're in the US, then you have a damn good chance of being part of a second bubonic plague.

In space...

[Anonymous Coward]

Where's the "noonecanhearyouscream" tag?

peer review you say?

[Anonymous Coward]

Since you guys refuse to read books that you do not already agree with, we will have to teach you EU Theory through peer reviewed papers. Gadzooks! Nobody should have to stoop to that level to conduct science, of all things! After all, Barnes & Noble is clogged with reliable books of fact that should convince any scientist! Amd by "we" in "we will have to teach you" I suppose you mean you're a qualified astrophysicist? Either way there have been plenty of very qualified and otherwise successful people with PhD's from prestigious schools who got things wrong. You have to pick carefully who you believe.

You're using the same argument by quantity that you just got done blasting: you say "EU Theory is not *popular*" and then you say "who have been reading astrophysical papers for 30 years" as if that's persuasive. There are still other such people who've been working on astrophysics at least that long who've reached different conclusions. We won't have to wait much longer to have the truth explained to us? I might be anxious like you for that event if it would shut you people up, but I don't think you'll accept any disproof anyway so I'm indifferent.

Re:peer review you say?

[pln2bz]

Amd by "we" in "we will have to teach you" I suppose you mean you're a qualified astrophysicist? Either way there have been plenty of very qualified and otherwise successful people with PhD's from prestigious schools who got things wrong. You have to pick carefully who you believe.

There's certainly no shame in claiming that I believe in Hannes Alfven. He did after all create magnetohydrodynamics.

You're using the same argument by quantity that you just got done blasting: you say "EU Theory is not *popular*" and then you say "who have been reading astrophysical papers for 30 years" as if that's persuasive. There are still other such people who've been working on astrophysics at least that long who've reached different conclusions. We won't have to wait much longer to have the truth explained to us? I might be anxious like you for that event if it would shut you people up, but I don't think you'll accept any disproof anyway so I'm indifferent.

As I tell my girlfriend all of the time, it's not a competition! The point is that there are very qualified physicists and astrophysicists, both internal and external to the peer review system, that have read what EU Theory states and agree that there is nothing technically wrong with its arguments. What I've noticed over time is that mainstream advocates do not just want to be right; they also demand that they not be challenged. They refuse to accept that there can be any debate about the fundamentals -- like the mathematical modeling of space plasmas. My purpose is not to demonstrate that EU Theory is certainly right. All that I and others wish is to be admitted into a meaningful debate. We want people to talk about the evidence with us. People like Tim Thompson and those on the BAUT Forums have proposed various simplistic arguments that have in the past been designed to dissuade people from looking into the issue. There was, if I remember correctly, a rather simplistic calculation some time ago on BAUT that got passed around a lot that supposedly demonstrated that there was not enough charged particles between us and the nearest star to power the Sun. Since then, as you may be aware, it has been observed that the solar wind's structure consists of many individual flux-tubes. From http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=APCPCS000932000001000026000001:

Recent studies suggest that flux-tube-like structures may exist in the solar wind. In this scenario, the solar wind plasma are confined in many individual flux tubes and plasma in these flux tubes move independently from each other. Within each flux tubes, the (MHD) turbulence is due to the local non-linear dynamics. Across the boundaries between adjacent flux tubes, however, the (MHD) turbulence receives another contribution from the sudden change of magnetic field directions between different flux tubes. Thus the solar wind turbulence will naturally be of multiscale and intermittent. In this paper, using the procedure we developed in [1], we analyze magnetic field data obtained from Ulysses spacecraft in both fast and slow solar wind, at various radii and latitudes. Our results show flux tubes exist in both the fast and the slow solar wind.

As you may know, a "flux tube" is conventional astrophysicist speak for the movement of charged particles within filaments. In other words, electrical currents. This is not some loonie crackpot meandering. If you were being rational and objective about it, you would wonder *why* the solar wind has flux tubes. If you were informed of EU Theory or even just laboratory plasma physics, you would also realize that it tends to point to Birkeland Currents, and very importantly, the observation violates quasi-neutrality. Not only is the simplistic calculation completely worthless, but the physical world is look