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Comment Hah, what? (Score 1) 29

Other swarm robotics research has looked at alternative resources such as alcohol, light and sound to simulate pheromones and swarm behaviour. However, these are complex and expensive methods compared to COS-phi, which simply combines the LCD screen and USB camera with an open-hardware micro-robot and an open source localisation system.

Oh, yeah, sure, those are other methods are really complex. All this this needs is to constrain the robots to roaming around on top of an LCD screen. That's practical.

Just because nature does something one way, doesn't mean it's the best way.

Comment Re:There needs to be a very detail visual 4D sim (Score 1) 102

The length is relevant because all of that dust, seen straight on, blocks a lot of light. Stack enough window panes (less than you'd think, probably) on top of each other and eventually you won't be able to see anything through them at all.

Then it's just a question of how wide a comet's tail can get, in order to get sufficient coverage of the star's shape as seen from Earth. And since the tail can be 720x longer than the star's diameter, I don't think it's much of a leap to think that it could spread out enough in the other two dimensions to do this.

Comment Re:There needs to be a very detail visual 4D sim (Score 1) 102

exactly and even more importantly 22% of the light of a star implies something somewhat transparent (like the tail of a comet) that is the full angular size of the star.

So? Tails can be up to 500,000,000 kilometres long. That's 720 times the Sun's diameter.

Is it that much of a leap to assume that it could actually spread out far enough to block a significant fraction of the star's light? It doesn't have to be the full angular size; about half would do, if the tail is sufficiently long to block out most of the light that passes through it.

We have no idea how an apparently dark object could be this big.

When you say "we" do you mean "modern science," or do you just mean "I"?

Comment Re:There needs to be a very detail visual 4D sim (Score 1) 102

Well again, given that a gas giant can only block 1-2%, this would have to be a really friggin' huge comet, right? A comet bigger than Jupiter?

A comet tail bigger than Jupiter. Such a thing has been observed in our own solar system.

Sure, the tail might help, but still comet tails don't block light the way a planet does, they're just a collection of dust.

They block light in exactly the same way a planet does, since they are also just a collection of atoms, just more diffuse.

A few dozen metres of water vapour in the form of clouds can block plenty of the light from our star.

Even if a comet tail only blocks, say, 0.1% of the light per million kilometres, it would still block a total of 40% of the light if you were looking straight down it at a star (assuming a length of 500,000,000km, as per comet Hyakutake).

Comment Re:A system like this might be super-habitable for (Score 1) 102

I think it's amazing that there could be a system with enough comets to block out such a big portion of starlight.

They think the first dimming event was caused by one comet.

I think the thing to grasp might be that - as the illustration on the article shows, albeit with some artistic licence - you need to imagine looking at the star through the entire millions-of-kilometres length of a dusty comet tail (which streams directly away from the star, so directly towards us). That'll block a lot of light, I'm guessing.

Comment Re:There needs to be a very detail visual 4D sim (Score 1) 102

If it is a regular cycle then the orbit also must be small.

I got that bit wrong. Only two dimming events have been recorded. One is thought to have been caused by a large leading comet, the other by trailing comets.

Even when close to us the largest known comets tails only would "cover" a small fraction of the visible area of our sun.

The largest known comet tail was 500,000,000km long. And they stream out directly away from the star, so imagine looking at a star through the entire 500,000,000km length of a dusty comet tail. You don't think that might obscure the light from the star a bit?

Imagine something created from colliding comets

That's a scenario the article specifically dismissses.

Comment Re:There needs to be a very detail visual 4D sim (Score 1) 102

how the heck would some comets block 20 times more?

How many is "some comets"? Why couldn't "some comets" block 20% of the light from a star? For that matter, why couldn't one comet do it? Remember a comet isn't just the nucleus. There's also a tail, which can be thousands of times longer than a mere planet.

Just have a look at the illustration that leads the article (probably not entirely to scale, but still).

Comment Re:There needs to be a very detail visual 4D sim (Score 3, Insightful) 102

Huh. Posted my reply as AC for some reason.

To reiterate:

22%. Something obscures 22% of the whole side of a star larger than the sun just in our specific direction.

No. Something blocks 22% of the light emitted in our direction for some amount of time in a regular cycle.

how could a few comets create this sort of thing unless the "clouds" they create are sucked into the star almost immediately?

Why would you expect the clouds to be "sucked in" at all?

To restore a sense of reality, I think Walt Disney should have a Hardluckland. -- Jack Paar