Hacker News Reader

Comment by dpq | Hacker News Reader

> The solar system is already close to a vacuum

No. Not at all. You can expect particle density to be anywhere from 5cm^-3 to 80cm^-3 if you stay within 1 astronomical unit distance from the Sun. Besides, all that plasma is accompanied by frozen-in magnetic field, plus you have energetic particle events, recurrent fast solar wind emerging from coronal holes and plethora of other effects and structures which are terribly interesting to study but which will ruin your high energy physics experiment even if you somehow acquire god-like powers and build a huge non-contiguous accelerator.

View on HN

With a space-based facility, it seems like we'd be able to observe the types of collisions we're talking about without bothering to build an accelerator at all, if we only knew when and where to look for the events.

https://en.wikipedia.org/wiki/Oh-My-God_particle

It's possible that forward progress in the post-LHC era will come from better sensing technology, rather than larger accelerators.

I was under the impression the best artificial vacuums here on earth are nowhere near as empty as space. Is that not the case?

People can get slightly better vacuum pressures in elaborate lab settings than are present on the moon. With trivial amounts of effort (and non-trivial sums of $), you can get within a couple orders of magnitude. Source: have done so myself.

The difference is that space is filled with lots of other stuff that makes running experiments less than ideal.

>5cm^-3 to 80cm^-3

had to look this up to see what you mean. I think you mean 5g(cm^-3) to 80g(cm^-3)

Um, water weighs 1g/cm3. He means 5 particles.

No he means 1 particle per that volume, or maybe that many particles per cm^3. The numbers you suggest are more dense than water.

alright, so 5 particles per cm^3 to 80 particles per cm^3, not grams (as density is normally measured).

i'm not sure why the downvotes were necessary though when I made it clear I was trying to figure out what he's saying.

Reply on news.ycombinator.com