Slashdot Mirror
Nearby, Recent Interplanetary Collision Inferred
The Bad Astronomer writes about a new discovery by the Spitzer Space Telescope, which detected signs of an interplanetary smashup only 100 light-years from here, and only a few thousand years ago. There's a NASA-produced animation of the collision between a Mercury-sized planet and a moon-sized impactor. The collision's aftermath was detected by the presence of what are essentially glass shards in orbit around the star. Here's NASA's writeup.
the guy posting the blog states: "the shock wave ring travels around the planet as shown, but when the ring converges on the point opposite the collision point, there would be a huge explosion and a vast plume of material launched into space. No one ever puts that in their animations"
I thought the same thing when I watched the video - there would be a godawful explosion at the antipode
The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday.
100 light-years! Boy that barely missed us, better put on your hardhats boys because the next mash up is said to be only 80 light-years away!
We should hope that whoever engineered this is not heading our way.
http://michaelsmith.id.au
That's no moon.
Hay, you have nothing to complain about. The notice was published in the Galactic Gazette by the Vogon destructor fleet for several centuries.
http://en.wikipedia.org/wiki/The_Hitchhiker's_Guide_to_the_Galaxy
Sig Battery depleted. Reverting to safe mode.
There are probably more efficient ways of wiping out life than pouring on the order of 10^30 joules into accelerating a gigantic impactor.
More efficient ways yes, but more satisfying?
If taxation is legalized theft, then Capitalism is a prolonged rape followed by a slow death.
Is it just me or is that coolest thing ever? Forget massive trains.. the male mind cannot help but drool at the idea of planets colliding.
Venus is awesome; I can't even imagine what that would look like. The impactor rapidly accelerating the rock around it while the rock on the other side of the planet crumples and deforms under titanic pressure. Maybe the crust would be rigid enough to accelerate rapidly in big chunks while the big oceans of rock in the mantle churn and slowly come up to speed.. or maybe it would just blast most of the mass spaceward, leaving the planet to be pelted by continent-sized rocks for the next thousand years..
But undoubtedly Uranus is the coolest collision. Gas giants are already terrifying (imagine falling straight down into the north pole of Jupiter, falling straight into the bullseye of roaring winds and bottomless stormclouds).. but a mass large enough to alter its inclination exploding through the upper atmosphere as a fireball, and slowly ablating as it buries itself deeper into progressively denser gases, and plunging deeper and deeper into the unplumbed depths of unimaginably violent, raging, endless storms, and finally sinking to the crushing depths of the great core furnace.. come on Hollywood, put your obscene special effects budget to use doing something like this.
There is a place. It is a place where broken rocks ring a red sun.
Several centuries ago, we discovered a race of arthropod-like creatures called Whilles, with whom we could not deal.
They rejected friendly overtures on the parts of every known intelligent race. Also, they slew our emissaries and sent their remains back to us, missing a few pieces here and there.
When first we contacted them, they possessed vehicles for travel within their own solar system. Shortly thereafter, they developed interstellar travel.
Wherever they went, they killed and they stole and then beat it back home.
Perhaps they didn't realize the size of the interstellar community at that time, or perhaps they didn't care.
They guessed right if they thought it would take an awfully long time to reach an accord when it came to declaring war on them.
There is actually very little precedent for interstellar war. The Pei'ans are about the only ones who remember any..
So the attacks failed, what remained of our forces were withdrawn, and we began to bombard the planet.
The Whilles were, however, further along technologically than we'd initially thought. They had a near-perfect defense system against missiles.
So we withdrew and tried to contain them. They didn't stop their raids, though.
Then the Names were contacted, and three worldscapers, Sang-ring of Greldei, Karth'ting of Mordei and I, were chosen by lot to use our abilities in reverse.
Later, within the system of the Whilles, beyond the orbit of their home world, a belt of asteroids began to collapse upon itself, forming a planetoid.
Rock by rock, it grew, and slowly it altered its course. We sat, with our machinery, beyond the orbit of the farthest planet, directing the new world's growth and its slow spiral inward.
When the Whilles realized what was happening, they tried to destroy it.
But it was too late. They never asked for mercy, and none of them tried to flee. They waited, and the day came.
The orbits of the two worlds intersected, and now it is a place where broken rocks ring a red sun. I stayed drunk for a week after that.
http://www.amazon.com/Isle-Dead-Eye-Roger-Zelazny/dp/0743434684/
Mit der Dummheit kämpfen Götter selbst vergebens
There are probably more efficient ways of wiping out life than pouring on the order of 10^30 joules into accelerating a gigantic impactor.
Put the same energy into lots of small relativistic impactors. Craft the trajectory so that the acceleration phase is masked by nearby stars. Distribute the impactors so that all orbital installations and both sides of all inhabited bodies are blanketed with enough energy to raise the temperature to 500 degrees celsius for all biomes. Time them, so that they all arrive at the same time. The victims will have only minutes of advance warning, if any at all. (Idea from _The Killing Star_)
TFA wrote:
That's like saying "somebody living within five miles of me was struck by lightning last week, so it seems incredibly unlikely that being struck by lightning is a rare event on this planet". A single sample says nothing about the probability of the event, other than that it's nonzero.
Hey, if you can't be bothered to take an interest in local affairs that's your own lookout.
Approximately 14,600.
Having an FTL drive doesn't mean it's a time machine. The actual method of travel is important here.
Yes actually FTL does mean you have a time machine, and the method of travel doesn't really matter. It's not like a Back to the Future time where you can arbitrarily go backwards and forwards as far as you want, it's limited to past-only and by how far and fast you can actually travel and how fast your non-superluminal spaceships can travel. But from some observer's reference frame you will have traveled back in time and broken causality by arriving at your destination before you left, simply by moving faster than c relative to them.
And if you incorporate a second FTL journey, it's actually possible to arrive at your starting point before you left according to all reference frames.
Here's an explanation. There's a nice explanation with graphs and everything .
Note that it does not depend on Lorentz Transformation of the super-luminal traveler/communication. The mechanism isn't important. That observers in normal, relativistic reference frames see you traveling faster than c is what is important. If you can do that, you can go back in time.
Whether or not time flows differently for the travelers (relative to the galactic frame of reference) depends entirely on the details of this technology that we do not yet have access to.
Time may pass differently for the travelers relative to some reference frame, but remember there are no privileged reference frames in Relativity. You can break causality if you go FTL relative to any reference frame, and if you aren't traveling FTL with respect to any reference frame, then you can't really be said to be traveling FTL can you?
The enemies of Democracy are
If that were true, quantum entanglement would break causality.
Not it wouldn't, because nothing is traveling faster than c in entanglement, not even information. In fact, it is exactly for the reason I'm describing that demonstrates why quantum entanglement can't be used to send information. Nor can any effect resulting from the entanglement being collapsed on the "other end" be distinguishable from it collapsing on your end. There is no possibility of breaking causality.
However macroscopic-you traveling FTL most definitely involves transferring mass and information and thus causality can be broken.
Actually, what we perceive as causality is a symptom, not the cause. Hence it's an illegal assumption that time travel would _have_ to occur every time local effects shift (for lack of a better word) between two points in space faster than it would take a photon to traverse.
Actually, causality is one of the basic assumptions of Relativity. That's how Einstein ended up arriving at the conclusion that nothing can travel faster than light. He assumed causality was inviolate, and he assumed that c was constant for all observers. It was the latter notion that led to the idea that different observers could see things happening at different times. And this led to the notion that if one could travel faster than c, some observer would see effect happen before cause, violating causality.
And I didn't say time travel necessarily had to happen in any particular instance of FTL. I said FTL necessarily allows for time travel. Which, if you look, every reference agrees with.
I think most people here, including possibly myself, already know about relativistic effects, there is no need to preach. The whole discussion was _not_ based on the idea of actually accelerating any quantity of matter to causality-breaking, faster-than-light speeds to begin with. There is simply no propulsion system that can do that. What we may be able to build, however, is a system that achieves the same effect by bending spacetime in a very neat way. This is what SciFi nerds call FTL. It's a theoretical system with theoretical properties. But _if_ it works, it's not a time machine simply because it teleports matter between two points "faster" than it would take a ray of light to do so.
Yes I understand that and I thought I was pretty clear in stating that I was not referring to an object accelerated past c. Any method of travel which appears to be super-luminal to any observer breaks causality. The poster was suggesting a method where some observer would agree that you traveled FTL, yet because you didn't "really" go FTL you get around Einstein's conclusion. That simply isn't true.
Energy-wise, accelerating anything to c is impossible. Causality-wise, going faster than c by any method is impossible. I'm a Sci-Fi nerd, and hey it's neat to think about warp driving letting you get FTL without actually having to accelerate to make it seem semi-plausible. Nevertheless, even though it doesn't work that way in Star Trek, warp drive allows time travel.
In order for it to really work, we need more than just warp drive. We also need to violate Relativity. Either causality is not inviolate, and time travel is really possible, or some other assumption of Relativity is broken. That's always possible, sure, but in a Relativistic universe, FTL == Time Travel. Seriously, look it up.
The enemies of Democracy are