In a on-going fascination with science I came across this while perusing the BBC science section. Perhaps some of you more informed can expand upon it and theorise the possibilities of instant communication across stellar and interstellar space:
Snip
The strangest and most disturbing fact that scientists uncovered while investigating the atom was a law called \"Heisenberg's Uncertainty Principle\".
In a nutshell, this states that atoms are in more than one place at the same time until a conscious observer looks at them.
Think about this for a moment - if no one's looking at the atoms that, say, make up your hand, they're effectively spread out across the entire universe.
Then when someone, maybe even you, looks at your hand, the atoms instantly coalesce into the hand-like shape you're familiar with.
If ideas like this make your head hurt, don't worry. Even Albert Einstein, who as a young man pioneered atomic physics, was horrified by the idea that we somehow \"invent\" the Universe every time we look at it.
End Snip
http://news.bbc.co.uk/2/hi/science/nature/6914175.stm
Heisenburg Principle
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Basically it boils down to the fact that you cannot simultenously know an atom's position and momentum -- you can know one with arbitrary certainty, but you can only estimate the other (Wikipedia does a decent job of explaining this more technically: link).
The BBC's statement about a \"conscious observer\" is wrong.
The BBC's statement about a \"conscious observer\" is wrong.
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Foil
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x2.
There's no \"instant coalescing of matter because a conscious observer looked at it\". That's basically a poor (albeit quite common) way to try to explain Heisenberg's Uncertainty Principle, which is as DCrazy described it: any observation of position and momentum has limitations of accuracy.
Another way to say it, without being too technical:
1. The more precisely you know a particle's position, the less precisely you know the particle's speed.
2. Conversely, the more precisely you know a particle's speed, the less precisely you know the particle's position.
The best \"layman's explanation\" for me is thinking of two pictures of a bullet in flight.
In one picture, the bullet's picture was taken with a very fast shutter. The image is crystal clear, so we can see it's position with a lot of accuracy. However, we can't get much indication of how fast it was moving.
In the second picture, the shutter was set a little slower, so the image shows a moving/blurred bullet. From this, we can measure how fast it was moving. However, we can't tell nearly as much about it's exact position.
Again, it has nothing to do with \"conscious observers\" or \"atoms spread across the universe\".
There's no \"instant coalescing of matter because a conscious observer looked at it\". That's basically a poor (albeit quite common) way to try to explain Heisenberg's Uncertainty Principle, which is as DCrazy described it: any observation of position and momentum has limitations of accuracy.
Another way to say it, without being too technical:
1. The more precisely you know a particle's position, the less precisely you know the particle's speed.
2. Conversely, the more precisely you know a particle's speed, the less precisely you know the particle's position.
The best \"layman's explanation\" for me is thinking of two pictures of a bullet in flight.
In one picture, the bullet's picture was taken with a very fast shutter. The image is crystal clear, so we can see it's position with a lot of accuracy. However, we can't get much indication of how fast it was moving.
In the second picture, the shutter was set a little slower, so the image shows a moving/blurred bullet. From this, we can measure how fast it was moving. However, we can't tell nearly as much about it's exact position.
Again, it has nothing to do with \"conscious observers\" or \"atoms spread across the universe\".
The requirement for a concious observer would have repercussions far beyond the scope of this theory. Scientologists and creationists would be all over it like a hobo on a ham sandwhich.
The wikipedia link was actually quite interesting (as difficult to understand as it may be). The only thing that i fail to grasp though, is why you can't know exactly an atom's position and speed at once?
I hate quantum physics, because before I read up on it Determinism used to be my main philosophy of reason. Damn particles popping in and out of existence on the quantum level shatter that philosphy.
The wikipedia link was actually quite interesting (as difficult to understand as it may be). The only thing that i fail to grasp though, is why you can't know exactly an atom's position and speed at once?
I hate quantum physics, because before I read up on it Determinism used to be my main philosophy of reason. Damn particles popping in and out of existence on the quantum level shatter that philosphy.
Re:
Relativity doesn't work on things that small.Blue wrote:The wikipedia link was actually quite interesting (as difficult to understand as it may be). The only thing that i fail to grasp though, is why you can't know exactly an atom's position and speed at once?
The problem is that an atom, or anything smaller, doesn't need to obey what we observe as linear time - they don't know about Relativity nor care about it. Knowing its position and velocity are two separate measurements, and by the time you finished making one, the atom either has gone off somewhere else or changed its speed entirely.
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Foil
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Exactly. Here's another way to see it (although I still think the \"bullet picture\" description above makes the most sense to me):
You can't get both speed and position from a single measurement.
So why can't you just do two measurements? Because a measurement can only be done via an interaction with the particle (e.g. hitting an atom with light/photons), so the interaction from the first measurement would actually change the particle's speed and/or position.
You can't get both speed and position from a single measurement.
So why can't you just do two measurements? Because a measurement can only be done via an interaction with the particle (e.g. hitting an atom with light/photons), so the interaction from the first measurement would actually change the particle's speed and/or position.
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It's important to remember that this has nothing to do with the uncertainty principle. It's just a reason that you can't get around it.Foil wrote: So why can't you just do two measurements? Because a measurement can only be done via an interaction with the particle (e.g. hitting an atom with light/photons), so the interaction from the first measurement would actually change the particle's speed and/or position.
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Foil
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You're right, thank you. I should have clarified that I was referring to the "Observer Effect", not the Uncertainty Principle.DCrazy wrote:It's important to remember that this has nothing to do with the uncertainty principle. It's just a reason that you can't get around it.
Coming back to woodchip's original snippet, it's important to point out that what the BBC is saying isn't necessarily \"incorrect\". It's \"wrong\" in the sense that their interpretation of the uncertainty principle isn't really what the principle is all about (and using the word \"conscious\" is incorrect, but that's minor). What the principle is saying is that there is a lower bound to the standard deviation of two measurements that are related in a certain way. Position and momentum obey this relationship to each other, as do a few other characteristics listed on the Wiki page.
The standard deviation is a measurement of the variation of a discrete variable (a dependent variable which only makes sense for a set of independent variables -- things like number of hot dogs eaten which can't be assigned nice continuously-defined mathematical functions). For a variable which doesn't change, the standard deviation of that variable is zero. For example, if everyone in the room ate the same number of hot dogs for lunch, stdev(hot dogs eaten) = 0.
Now, this is just a number. You can multiply it by other numbers. When talking about the uncertainty principle, we're talking about the product of two standard deviations being greater than some constant number. So all the uncertainty principle is saying is that stdev(variable a) * stdev(variable b) >= some number C which never changes.
But what's odd is exactly what \"variable a\" and \"variable b\" refer to. The uncertainty principle is talking about the value of two certain characteristics of a particle taken over multiple observations at the exact same state. So think if I were to make five identical copies of the universe and freeze them in time at the exact same moment. If I choose a particular electron and measure that same electron's position and momentum relative to some arbitrary point in all five universes, you would expect that I would get the same answer for each of the ten computations (five universes, two characteristics) that I do. In other words, stdev(position of the same electron in each universe) = stdev(momentum of the same electron in each universe) = 0.
The uncertainty principle, bizarrely enough, says NO. In fact, it goes further than that, and says specifically that if I multiply the two standard deviations together I will ALWAYS get a number that is greater than or equal to a certain constant number.
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What does this all mean? It means that we can never definitively say where a particle is in the universe, its mass, and how fast/in what direction it is traveling at the same time. Instead, we can pick any point in space at a specific moment and calculate what the likelihood of a certain particle being at that position and having that momentum (etc...). But we can never say for sure.
The standard deviation is a measurement of the variation of a discrete variable (a dependent variable which only makes sense for a set of independent variables -- things like number of hot dogs eaten which can't be assigned nice continuously-defined mathematical functions). For a variable which doesn't change, the standard deviation of that variable is zero. For example, if everyone in the room ate the same number of hot dogs for lunch, stdev(hot dogs eaten) = 0.
Now, this is just a number. You can multiply it by other numbers. When talking about the uncertainty principle, we're talking about the product of two standard deviations being greater than some constant number. So all the uncertainty principle is saying is that stdev(variable a) * stdev(variable b) >= some number C which never changes.
But what's odd is exactly what \"variable a\" and \"variable b\" refer to. The uncertainty principle is talking about the value of two certain characteristics of a particle taken over multiple observations at the exact same state. So think if I were to make five identical copies of the universe and freeze them in time at the exact same moment. If I choose a particular electron and measure that same electron's position and momentum relative to some arbitrary point in all five universes, you would expect that I would get the same answer for each of the ten computations (five universes, two characteristics) that I do. In other words, stdev(position of the same electron in each universe) = stdev(momentum of the same electron in each universe) = 0.
The uncertainty principle, bizarrely enough, says NO. In fact, it goes further than that, and says specifically that if I multiply the two standard deviations together I will ALWAYS get a number that is greater than or equal to a certain constant number.
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What does this all mean? It means that we can never definitively say where a particle is in the universe, its mass, and how fast/in what direction it is traveling at the same time. Instead, we can pick any point in space at a specific moment and calculate what the likelihood of a certain particle being at that position and having that momentum (etc...). But we can never say for sure.
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Lothar
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Re:
It means that the position and velocity waves that describe a particle can't both be constrained at the same time -- as one of them is constrained more tightly, the other expands.DCrazy wrote:If I choose a particular electron and measure that same electron's position and momentum relative to some arbitrary point in all five universes, you would expect that I would get the same answer for each of the ten computations (five universes, two characteristics) that I do. In other words, stdev(position of the same electron in each universe) = stdev(momentum of the same electron in each universe) = 0.
The uncertainty principle, bizarrely enough, says NO. In fact, it goes further than that, and says specifically that if I multiply the two standard deviations together I will ALWAYS get a number that is greater than or equal to a certain constant number.
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What does this all mean?
It's really not that hard if you're willing to accept the idea that particles are actually waves, and that what you're measuring is a sampling of the wave, rather than the whole wave. When you measure the two particle characteristics in N different universes, for N large enough, you should end up reconstructing the pair of waves... because that's what you measured in the first place!