Slashdot Mirror
Study: Space Rock Impacts Not Random
sciencehabit writes When it comes to small space rocks blowing up in Earth's atmosphere, not all days are created equal. Scientists have found that, contrary to what they thought, such events are not random, and these explosions may occur more frequently on certain days. Rather than random occurrences, many large airbursts might result from collisions between Earth and streams of debris associated with small asteroids or comets. The new findings may help astronomers narrow their search for objects in orbits that threaten Earth, the researchers suggest.
http://en.wikipedia.org/wiki/M...
http://stardate.org/nightsky/m...
I knew you could
I would have thought this was common sense.
Instead of believing The Giant Flying Spaghetti Monster likes to randomly through rocks at us from up on high, we instead correlate that higher meteor activity is linked to Earths passing through debris fields from existing comet trails, the SAME trails every X amount of years.
Sounds like a story from the 1800's
YMMV, but I like top hide under my bed.
Why is Snark Required?
It's even worse than that. Going by this quote, they're using it to mean even or homogeneous:
contrary to what they thought, such events are not random, and these explosions may occur more frequently on certain days.
You know, like if a coin comes up heads four times in a row that's "not random".
As to the astronomy bit, this has been known since forever. The major ones have names and can even be predicted. Crapdot FTL.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Because then, we'd find many to threaten earth!
Well predict what a dice roll will be. Yet that *is* based 100% on nothing but deterministic physics.
If information wants to be free, why does my internet connection cost so much?
Is, or is not, physics at a macro scale deterministic or not?
Yes and no. Chaos theory concerns itself with problems that are, for all (or most) practical purposes, unpredictable. IOW, these problems are, in principle, deterministic, but in practice, very difficult to solve with any degree of precision. The weather, for example - if we know the starting conditions exactly for every point on the planet (and our models were perfect), we should be able to predict the temperature, wind speed etc exactly for any point in and time, ever, and for any spot on the planet. Unfortunately, small variations in start parameters result in huge variations in end results, which is why weather forecasting is so hit and miss.
One has to accept that, in common usage, the word 'random' simply means 'chaotic' in the above sense.
Someone already said that God doesn't play dice. But I cannot remember the name ...
Sent as ripples into the electromagnetic field. No single photon has been harmed in the process.
Haven't we known this for like fucking ever?
By "random" you mean "as yet unexplained"
Which is the standard use of the word.
so they looked at *big* rocks, not small rocks. We know that small rocks often come in showers as comet tails or clouds of assorted crap that we pass through. This study was on the big rocks that are not known to be part of specfic meteor showers like the leonids or whatever. They were previously thought to be fairly random, however the tests they did basically prove that meteor impacts are not a particularly good source of entropy for /dev/random (well, apart from the multiple obvious reasons not to feed them into /dev/random, they are also not sufficiently random and unrelated to each other)
I predict 100% certain the next roll will not be a 7
Cryonics - Keep cool and carry on.
And, similarly, "chaotic" is not an explanation, either.
Would you accept "inherently impossible to predict any significant length of time ahead"? It's all very well to pick on the reason for the unpredictability (be it quantum uncertainty or extreme sensitivity to initial conditions because of non-linearity) but at a functional level, the outcome is similar: some stuff just can't be predicted in detail long term, and will continue to be like this whatever we do.
"Little does he know, but there is no 'I' in 'Idiot'!"
Even simpler: some stuff can't be predicted simply because you don't have sufficient knowledge of the process or its input conditions. A slot machine could be driven by a simple pseudo random generator, 100% predictable, as long as you know the algorithm and the seed. Since the gambler doesn't have access to this information, the spinning dials are completely random to him.
It is a d20. We are rolling for damage.
If information wants to be free, why does my internet connection cost so much?
It's a bit worse than that. The Heisenberg uncertainty principle states that you are not allowed by the laws of physics to simultaneously know all the initial conditions with arbitrarily high precision.
...that this is news?
I'm not an astronomer, but I was pretty sure that the idea that the US passes through periodic 'clouds' of debris was as old as astronomy - how is this substantially different than the Leonid (passing through the debris left by comet Swift-Tuttle)or Perseid meteor shower (passing through the debris left by comet Tempel-Tuttle)?
Personally, I've wondered if some of these could coincide with truly massive volcanic eruptions or meteorite impacts historically, the ones hefty enough to land earth rocks on the moon or Mars. Such an eruption would, it seems to me, leave a 'cloud' of very small debris with its own orbit that would logically impact earth's orbit at the point they were created.
-Styopa
The small space rocks that shower the Earth at regular intervals are small because a big rock once collided with the Earth, sending debris into an orbit around the Sun that regularly intersects with the Earth's. Those rocks pose no current threat to the Earth, their damage was done at the time of mass extinctions past, or when the oceans were carved out, or what ever other distant past event they caused. The ones to worry about are the large interstellar rocks that haven't hit yet. So no, this does not help narrow the search for objects that threaten the Earth at all.
If the input conditions are somewhat more constrained than "the current state of the universe". If the algorithm can be executed on hardware that is any simpler than the physical machine.
Slashdot: where don knuth is an idiot because he cant grasp the awesome power of php
The Heisenberg uncertainty principle states that you are not allowed by the laws of physics to simultaneously know all the initial conditions with arbitrarily high precision.
Perhaps - although this is actually not uncontroversial. There are many things surrounding the interpretation of QM that are not entirely certain - I am aware that every so often somebody comes up with a 'proof' that Heisenberg is more fundamental than simply an effect of our mode of observation. We measure properties of microscopic matter by bombarding it with particles and measuring the statistical outcome of a large number of events; the observation that particles are waves and waves have a minimum 'resolution' led to Heisenberg's original proposal, and many arguments have been put forward to the effect that this is a fundamental property of nature and impossible to get around, but there are works going on trying to achieve exactly that: a better resolution than Heisenberg's uncertainty allows us.
Would you like to know more?
Get free satoshi (Bitcoin) and Dogecoins
Scientists discover Space Rock Friday!
Dear Slashdot, this has been known for almost 200 years.
And I wouldn't be surprised if Newton also knew this 350 years go but forgot to write it down.
To all the commenters claiming we've already known this for centuries... no, we haven't. There's no reason to presume a priori that large objects occur in "showers" like the smaller (ash particle to pea sized) objects that make up familiar meteor showers. And astrostatisticians are very unhappy with the quality of the statistics in this paper, and they are suggesting the null hypothesis can't be rejecting using better statistical tools: https://astrostatistics.wordpr...
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
One has to accept that, in common usage, the word 'random' simply means 'chaotic' in the above sense.
That doesn't make it acceptable in scientific usage.
contrary to what they thought, such events are not random,
Random? Ask the good people on the Rodger Young who were attacked by a lobbed meteor from the Klendathu system, or the near 10 million lives lost in Buenos Aires when that rock landed. Good people. Innocent people. The SkyMarshal is gathering for an all out retaliatory strike to avenge the deaths. It would be an excellent time to step up and serve and become a citizen! Do your part now!
Would you like to know more?
http://www.youtube.com/watch?v...
http://starshiptroopers.wikia....
Heisenberg's uncertainty principle is just an application of the Fourier uncertainty principle to the quantum position and momentum wavefunctions. Since those are a Fourier pair, the Fourier uncertainty principle applies. So it's not a matter of which interpretation you pick, it's about whether QM is correct. If the behavior of quanta is not wholly determined by their wavefunctions then QM is wrong, and Heisenberg's uncertainty principle might be violated, since the true functions for position and momentum may not be Fourier pairs. This is widely considered to be extremely unlikely. Also, if spacetime is quantized (there's a minimum possible distance and a minimum possible time, and all times/distances are integer multiples of these minima) then the wavefunctions wouldn't be continuous, so the uncertainty principles might not be applicable. Loop Quantum Gravity is one theory that posits this.
Not a sentence!
What plaything can you offer me today?
http://www.theonion.com/articl...
You can trivially make large events depend on nuclear decay, thereby breaking macro world determinism.
Finally! A year of moderation! Ready for 2019?
why do meteorites "expode" in the atmosphere? Can someone post a simple explanation? Yes, I know stuff gets hot when it flies through the atmosphere at very high speeds, but what is the mechanism for a kilo/mega ton explosion? Why don't they just ablate (is that the right word)?
So you're just a little rock drifting in space, perhaps you have a bit of slow elliptical gig with the Sun or some heavy vector from rude encounters with other Astrobumps and potato-lumps. But these vectors have mostly cancelled each other and you're copa-centric with the solar system, just chillin'.
Every now and then you wiggle-woggle as a giant vacuum cleaner that is Jupiter or Mars passes, which leaves you a bit perturbed but its song is so enticing. You do a little dusting now and then to spruce up the neighborhood and your day/night sides fill you with just enough electrostatic tickle and a tug of graviton tockle to gather little bits. Just a big lovable clump, like a giant iron-filled molar enjoying the solitude of space grooving on the universe.
But the groove is changing. You are humming with beacons and bitcoms and bacon commercials, ringing with SATCOM beams and HF RTTY streams, and music and bouncy over-the-horizon PAVE PAWS and wave claws of a modern age. And music, voices! Millions of voices. Single sideband gwobbles and gwerps, AM throbby-bumps and gurgle-beats, quavering FM and chaotic barking bursty bits channelized and encrypted for your protection. Lissen up party people, meat is in the house. And it's talking.
And IT is the source, that THING, a rolling blue ball with puffy white squiggles tumbling towards you. Clearly this is a bad place to be because it is headed in your direction and its inhabitants are too stupid or inconsiderate to move it aside.
Its mass tugs at you as a thin layer of atmosphere sears blazing heat through your little rocky self. It becomes thicker and you dissolve in an explosion of heat and light. Your elementary particles will add mass to this malevolent menace as a few creatures point their stubby fingers at your death and say, "Ooooooooooooooo!".
Then they will get on their cell phones and blabble over the radio accusing YOU of attacking THEM.
Stoopid PEOPLE on their BIG BLUE DEATH MARBLE.
<blink>down the rabbit hole</blink>
Just when you thought it couldn't get any worse after the weekend along comes a space rock to turn your already bad Monday into something even worse.
Cheers,
Dave
They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty.
Ben
But aren't we now finding ways around the Fourier uncertainty? I believe there was a recent Nobel price for advances in microscopy.
... it's about whether QM is correct.
That one is easy: QM is not correct. It is a model - ie. a best approximation etc, but there is almost certainly going to be something, somewhere that is not entirely covered by the model. Isn't that what we all hope for: that we discover something new and amazing?
... if spacetime is quantized (there's a minimum possible distance and a minimum possible time, and all times/distances are integer multiples of these minima) then the wavefunctions wouldn't be continuous...
Ah, but continuity is a matter of topology. If space itself is quantized, the topology would have to be restricted to fit space, and wavefunctions may well be not only continuous, but also smooth, if a suitable geometry can be constructed. This, in a way, illustrates the gripes I have with QM; there is almost a culture of mysticism surrounding it (or its interpretation), that stops you from reaching a deeper understanding, because you expect it to be fundamentally impossible - so you tend to lapse back into a classical mode of consideration. Thus, the typical line of thought becomes something like "1) What would the classical scenario look like?, 2) Construct the Hamiltonian 3) Apply The Magical Transformation and get a differential equation, 4) Solve to get the wavefunction". Nowhere in this process is an understanding deeper than classical mechanics required, and that, I suspect, is why people keep talking about space being discontinuous. Einstein's genius, IMO, was that he understood that physics must be intrinsic to space, and that the resulting geometry plays a dominant role in how the laws of physics work. So, even if space turns out to be a finely minced subspace of an embedding, Cartesian space, that is not actually relevant, since all the physics - the 'reality' if you like - is confined to the geometry of that subspace, and the geometry is the only interaction there is between physical space and the embedding space.