More evidence that Voyager has exited the solar system | Hacker News Reader

More evidence that Voyager has exited the solar system

blog.chron.com

170 pointsspullara35 comments

All these articles are a bit meaningless to someone, such as me, that don't even know what the definition of the solar system is (and no article seems to care about it).

To me, the solar system is just a heap of planets orbiting the sun. With that definition once you pass the orbit of the last planet your have exited the solar system (although since the orbits aren't circular and they all are in the ~same plane there sure is still some room for debate about the exact border of the solar system) - and consequently when pluto was excluded the size of the solar system shrank.

I don't imagine that my simple view of the matter is in any way accurate, but considering that noone seems to know where och what is supposed to happen when you leave the solar system, what are we then waiting for?

That something odd is happening and then, aha! That must be it! This is from now on the definition of the end of the solar system?

Sure, there might be a border where cosmic rays from outside of the solar system greatly increase etc. but does that have to coincide with the definition of the solar system?

Space is not 'space' (ie, a vaccum) in the solar system, viz

http://en.wikipedia.org/wiki/Interplanetary_medium [1]

At the edge of the sun's impact, there is a transition zone. That transition zone is the subject of this discussion.

Its the 'solar' that makes it a system. the solar system is sort of like the earths atmoshpere, in that regard. At a certain stage there is a transistion into the next level.

This is probably oversimplified, but has the important general idea out on the table. Others can refine as appropriate.

[1] http://news.ycombinator.com/item?id=4619870

There is no clear definition for the edge of the solar system[1]. The Voyager spacecraft are helping to define it.

The heliopause is a pretty reasonable way to define the edge of the solar system. A stated goal of the Voyager mission is to search for the heliopause boundary[2]:

Both Voyagers are headed towards the outer boundary of the solar system in search of the heliopause, the region where the Sun's influence wanes and the beginning of interstellar space can be sensed. The heliopause has never been reached by any spacecraft; the Voyagers may be the first to pass through this region, which is thought to exist somewhere from 8 to 14 billion miles from the Sun. This is where the million-mile-per-hour solar winds slows to about 250,000 miles per hour—the first indication that the wind is nearing the heliopause. The Voyagers should cross the heliopause 10 to 20 years after reaching the termination shock.

That having been said, this is a poor title. The news is not that the spacecraft has simply crossed a boundary. The news is that the boundary, until now unknown, was discovered (potentially).

The difference is "Ship successfully crosses Atlantic Ocean" vs "Columbus discovers New World". Perhaps a better title would be "More evidence that Voyager 1 has found the heliopause, considered to be the edge of the solar system".

----

[1] http://en.wikipedia.org/wiki/Solar_System#Farthest_regions

[2] http://voyager.jpl.nasa.gov/mission/interstellar.html

  There is no clear definition for the edge of the solar system[1]. 
  The Voyager spacecraft are helping to define it.

I think this is a very important observation. Thanks!

Others posted this link http://en.wikipedia.org/wiki/Heliosphere which helped me learn about the Heliosphere; The idea is that there's a boundary line created, instead of constant gradual reduction, because the sun's solar winds are no longer strong enough to counter the energies coming from the rest of the universe. Pretty fucking cool to all think about.

Could anyone explain to me why there's such a dramatic change in the incidence of extra-solar high energy cosmic rays or the incidence of solar particles? Without reading this article, I would have guessed that those graphs should've tailed off "smoothly" as distance from the sun increases, but what we're seeing instead is more of a "phase change". What about the underlying physics at a certain distance causes this very discontinuos behavior, and why this distance specifically? I imagine this cutoff distance must be a function of properties of our sun like luminosity, magnetic field strength, etc.

Well the data looks close enough to these theories http://en.wikipedia.org/wiki/Heliosphere

Thanks. I think this part describes why: http://en.wikipedia.org/wiki/Heliosphere#Heliopause

    The heliopause is the theoretical boundary where
    the Sun's solar wind is stopped by the interstellar 
    medium; where the solar wind's strength is no longer 
    great enough to push back the stellar winds of the 
    surrounding stars.

It is curious that the wiki mentions Voyager I data for some claims and we use those to verify Voyager I data?

1) When you have a hypothesis, you conduct an experiment.

2) When your experiment yields results that match your hypothesis, you consider that evidence.

3) When you have sufficient evidence, you upgrade your hypothesis to a theorem.

According to the Wikipedia article, we've got at least two probes that are producing results in line with our hypotheses. The bar for wikipedia is "sourced", not proven theorem with scientific rigor. In this case, we're in some nebulous area between 2 and 3. I think that meets the bar for an encyclopedia, which is intended to serve as a summary for these types of things.

Hit the sources and the transitive closure of references for more details.

> 3) When you have sufficient evidence, you upgrade your hypothesis to a theorem.

A theorem is a mathematical result: something proved logically from (possibly physical) assumptions.

Such as the four colour theorem? en.wikipedia.org/wiki/Four_colour_theorem

Especially the four colour theorem - the first mathematical theorem to be proved with software. That said, I believe this discussion pertains to the hypothesis -> theory "upgrade", not to theorems.

The point I was hinting at was that some theorems can be proven by a sufficient body of evidence rather than requiring logical deduction - the four colour theorem being a good example as it was proven by 'brute force' rather than analytically.

Doesn't a logical proof count as evidence? To my mind, these two methods are demonstrating the same thing: considering all the possible inputs, we can show [using logic|by testing them all] that the output meets our criteria.

To my mind, in this context, the difference between maths and physics is that maths is exhaustive while in physics we don't usually have exhaustive evidence so we have to work with what we've got.

Interesting question - to me, the distinction is that 'evidence' of the validity of something is expected output(s) given known input(s), whereas 'proof' (at least in the mathematical sense) is a logical transformation that is applied to make it obvious that the theorem must be true. I'm not sure you could call a proof 'evidence' because it's not an output of the theorem - it is the theorem.

I'm less certain than I was before I read your post, though - so I stand to be corrected :-)

I meant to say "theory", as in gravity.

There are two things: The strength (energy) of the particles, and the number of them.

The particles slow down because they press against the electric field of interstellar particles. So the energy will smoothly go down as Voyager gets farther.

But the number of particles won't change. The number will reach zero once the particles slow down so much they turn around and go the other way but until that point the number of particles won't change.

It would be interesting to see a graph of the energy levels, but I don't know if Voyager carries such a device.

Considering that it has enough power to continue data communications with Earth till 2025, it should be well into the heliosphere. If it keeps going at its current speed of 17km/s, it should reach the nearest star by the year 75,787.

Oh man. Can't wait. I'm totally keeping my calender clear on 75,787.

Non sequitur much? Only two of those sentences have anything to do with each other, and one factoid argues against the interestingness of another.

>Only two of those sentences have anything to do with each other

Err.. I only see two sentences in total. Where is the non sequitur?

Yeah, I meant clauses. Translation error.

I imagine that our descendants will have a certain kind empathetic pity on us for not knowing this for certain in the same way we look back on people not knowing what atoms were.

I love this -- it's always fun to think about what aspects of our modern science people will one day scoff at.

Some I always consider:

- Cures for disease

- Our understanding of space

- Transportation

Your assuming our descendants aren't living in a post apocalyptic dystopia where civilized society is little more than a fairytale. We may seem like gods to them. And it may be much closer than people expect, perhaps hundreds not thousands of years.

or like 10 years

As I understand it, almost every cancer treatment consists in gradually killing the patient in such a way that the cancer dies, hopefully before the healthy tissue, and then nursing the patient back to health. If we ever find a better approach, people will be utterly horrified at chemo and radiation therapy.

That is true for cancers without targeted therapies. But cancers such as CML, breast cancer, melanoma, etc, all now have targeted therapies against specific molecules (often tyrosine kinases).

While alkylating agents, etc, are still widely used, I think it's fair to say that the future that you have described is the present. We have the better approach, and now it's a matter of aggressively pursuing it (which is also happening).

Or now nearly the year 2013 a grandfather has to convince his grandson "Yes we sent men to the moon, they walked on it." grandson "Wow awesome!"

Some earlier versions of mankind had great knowledge too and not all of that has been preserved for us. Try to rebuild the Pyramids of Gizeh today for example. Do we today know exactly how this stuff worked?

It's pretty easy for us to rebuild the pyramids today, but what's hard is trying to do so with the same level of technology the Egyptians probably had at the time, which makes them wonders of the world instead of just another easy-to-make mudhut.

I'm personally getting a little tired of this. It seems to me that every 2 months for the last few years I've seen a new article titled "voyager has left the solar system". Perhaps I'm just ignorant but I can't help but think to myself "what... Again? " each time I hear it.

You should try reading the article.

    Will she ever return? No, she'll never return.
    What knowledge we will learn!
    She'll voyage forever in the inky blackness.
    She's the probe who'll never return.

To the tune of "Charlie on the M.T.A.":

http://www.mit.edu/~jdreed/t/charlie.html

Reply on news.ycombinator.com