Quantum Probability

[Gen1GT]

As far as I can understand, a particle can be absolutely measured for momentum or location inversely proportional to each other.

 

So if we're measuring an electron's momentum absolutely, then its position is entirely unknowable.

 

However, do electrons not travel at the speed of light? If we nab an electron to measure its position, why can we not assume it was travelling at the speed of light just before we measured it, therefore measuring absolute momentum and position?

 

I'm a quantum rookie, so be kind to me and my ignorant question!

[ydoaPs]

However, do electrons not travel at the speed of light?

No, they do not. Electrons have mass, so they're stuck below c.

[Mike Smith Cosmos]

As far as I can understand, a particle can be absolutely measured for momentum or location inversely proportional to each other.

 

So if we're measuring an electron's momentum absolutely, then its position is entirely unknowable.

 

However, do electrons not travel at the speed of light? If we nab an electron to measure its position, why can we not assume it was travelling at the speed of light just before we measured it, therefore measuring absolute momentum and position?

 

I'm a quantum rookie, so be kind to me and my ignorant question!

 

 

Hi.

 

There is a post Called " Heisenberg Principle " about (7 or 8 down) the list on quantum physics which has a fair bit of discussion on this point.

 

It May help. Then again it may not !

Edited January 14, 2013 by Mike Smith Cosmos

[Bill Angel]

No, they do not. Electrons have mass, so they're stuck below c.

And it's the Higgs field that interacts with the electron, giving it mass and limiting its speed to less than the speed of light.

[elfmotat]

As far as electrons go, they have nonzero mass so they cannot possibly travel at c. For massless particles like photons which do travel at c, their momentum is independent of their velocity. Their momentum is related to their energy/frequency.

[SamBridge]

It's also important to note that an electron isn't actually "orbiting: around a nucleus like a planet around a star, it's oscillating around it which doesn't require physical acceleration or really even velocity.

[Gen1GT]

Okay, sorry, I guess I should have used a massless particle as my example. However, I think elfmotat answered my question, and let me see if I got this correct:

 

A photon, although it has no mass, has momentum because of the energy contained based in its frequency and amplitude?

 

If a photon hits a Charge Coupled Device, and assuming there is a vacuum, can we not then observe its location (it was on the surface of the CCD), it's amplitude (intensity of light on the CCD) and its frequency (colour on the CCD)?

 

Once again, I'm sure this is a rookie question, so thanks for your patience.

 

On a side note...how slow can an electron move, it not the speed of light?

It's also important to note that an electron isn't actually "orbiting: around a nucleus like a planet around a star, it's oscillating around it which doesn't require physical acceleration or really even velocity.

 

But it does move when in an electrical circuit, correct?

[swansont]

A photon, although it has no mass, has momentum because of the energy contained based in its frequency and amplitude?

 

If a photon hits a Charge Coupled Device, and assuming there is a vacuum, can we not then observe its location (it was on the surface of the CCD), it's amplitude (intensity of light on the CCD) and its frequency (colour on the CCD)?

 

A single photon doesn't have an amplitude; its energy depends on the frequency.

 

If it hits a CCD, you can localize it to the pixel size of the array, and know that it had a component of momentum in that direction. However, it could have been moving with a transverse momentum as well (i.e. not normal to the surface), so this really doesn't pin down position and momentum to great precision.

 

On a side note...how slow can an electron move, it not the speed of light?

 

The lower limit is zero.

[Mike Smith Cosmos]

And it's the Higgs field that interacts with the electron, giving it mass and limiting its speed to less than the speed of light.

 

Is the Higgs field 'everywhere' . Like everywhere where there is SPACE-TIME, as opposed to the ' Nothingness' which presumably is just over the border of Space-time.

[SamBridge]

 

Is the Higgs field 'everywhere' . Like everywhere where there is SPACE-TIME, as opposed to the ' Nothingness' which presumably is just over the border of Space-time.

If there were truly nothing then that's what there would be, nothing, there wouldn't even be "distance". There is some medium for the existence of existence, and in every 3-D location that exists, a fermion will have mass, so I could only extrapolate that higg's fields, like the probability of particles themselves are in fact "everywhere".

[Gen1GT]

Swansont, if an electron can have zero velocity, does that mean we can put it on a box like a soccarball in a bathroom?

[Mike Smith Cosmos]

If there were truly nothing then that's what there would be, nothing, there wouldn't even be "distance". There is some medium for the existence of existence, and in every 3-D location that exists, a fermion will have mass, so I could only extrapolate that higg's fields, like the probability of particles themselves are in fact "everywhere".

 

Ok so here is this medium, which I presume you mean " space -time" filled with the Higgs field. And at no further distance 'over there' is 'nothingness'. Fine. but how far out has this "Space-time " containing Higgs field 'gone' (in its initial inflationary Z....i....iipp out?)

[SamBridge]

 

Ok so here is this medium, which I presume you mean " space -time" filled with the Higgs field. And at no further distance 'over there' is 'nothingness'. Fine. but how far out has this "Space-time " containing Higgs field 'gone' (in its initial inflationary Z....i....iipp out?)

The state of a Higg's field will extend indefinitely, so if there is a state of a localized higg's field that has been around since the beginning of the universe, it should theoretically have the size of the universe if the universe can only expand at the speed of light and if it was expanding at all, otherwise all the changes that happened happened at the speed of light at later times, and so those field states aren't the size of the universe. If you could travel faster than light, you could outrun the state of a change field before a star collapsed and measure it still to have the mass that it had before from its frame of reference it had supernova-ed. So basically any change to interact with something will happen at the speed of light, which is the basic principal we have now, gravity instantaneously reacts with anything within it's static field, but any change to that field happens at the speed of light. Higg's particles do exist literally everywhere, but the same field states do not.

Edited January 16, 2013 by SamBridge

[MigL]

Electrons are very claustrophobic. If you try to localize one within a box ( made of atoms ), at some point the electron will experience degeneracy pressure from being too close to the state of another electron, and will as a result become extremely frantic and energetic. When this energy ( as momentum ) requires the speed of the electron to approach the speed of light, the electron cannot increase its momentum any further, no matter if the pressure sqeezing it is equivalent to a white dwarf star. However it can continue to increase its energy and momentum if it becomes more massive. It does this by merging with a proton to form a neutron. This is what happens in neutron stars where neutron degeneracy then rules.

 

The Higgs mechanism was active during the electroweak dissociation era. An era too energetic for our current particles. It must therefore influence the whole universe. And no, there is no 'outside'.

[Mike Smith Cosmos]

Electrons are very claustrophobic. If you try to localize one within a box ( made of atoms ), at some point the electron will experience degeneracy pressure from being too close to the state of another electron, and will as a result become extremely frantic and energetic. When this energy ( as momentum ) requires the speed of the electron to approach the speed of light, the electron cannot increase its momentum any further, no matter if the pressure sqeezing it is equivalent to a white dwarf star. However it can continue to increase its energy and momentum if it becomes more massive. It does this by merging with a proton to form a neutron. This is what happens in neutron stars where neutron degeneracy then rules.

 

The Higgs mechanism was active during the electroweak dissociation era. An era too energetic for our current particles. It must therefore influence the whole universe. And no, there is no 'outside'.

 

Ok. I have got that. About the degeneracy, and how the Neutron stars form. So in the early fire ball of the big bang, the quarks combined First into Neutrons , then to protons and electrons, plus presumably the Higgs field shot out into the 'blue yonder' before everything else arrived up at that boundary between .....something .... and nothingness ...............Pushing the nothingness forward ahead of itself

 

Then 300 -400 thousand years later the free electrons recombined with the protons to make hydrogen everywhere, at least for a while .

 

Thanks.

[SamBridge]

 

Ok. I have got that. About the degeneracy, and how the Neutron stars form. So in the early fire ball of the big bang, the quarks combined First into Neutrons , then to protons and electrons, plus presumably the Higgs field shot out into the 'blue yonder' before everything else arrived up at that boundary between .....something .... and nothingness ...............Pushing the nothingness forward ahead of itself

 

Then 300 -400 thousand years later the free electrons recombined with the protons to make hydrogen everywhere, at least for a while .

 

Thanks.

That's more of a pop-science story, really we have no idea about the state of the universe at all before a few hundred thousand years after it supposedly was formed, and every couple years we keep finding it was older and larger than we previously thought. Maybe our entire observable universe is just a local cluster in an infinite universe, maybe space existed before and the big bang wasn't the beginning, ect.

[Gen1GT]

That's more of a pop-science story, really we have no idea about the state of the universe at all before a few hundred thousand years after it supposedly was formed, and every couple years we keep finding it was older and larger than we previously thought. Maybe our entire observable universe is just a local cluster in an infinite universe, maybe space existed before and the big bang wasn't the beginning, ect.

 

And maybe the multi-verse was created by the eternal flying spaghetti monster. Call me a sellout bandwagon rider, but I generally like to conform to the accepted theories of thousands of hyper-geniuses. If Stephen Hawking feels there was neither time nor space before the big bang, who am I to argue or presume otherwise? Although he was wrong about black holes, everyone is going to be wrong once in their lives, right?

[SamBridge]

 

And maybe the multi-verse was created by the eternal flying spaghetti monster. Call me a sellout bandwagon rider, but I generally like to conform to the accepted theories of thousands of hyper-geniuses. If Stephen Hawking feels there was neither time nor space before the big bang, who am I to argue or presume otherwise? Although he was wrong about black holes, everyone is going to be wrong once in their lives, right?

You can say otherwise all you want because there are other super-geniuses who doubt multi-verses and geniuses who doubt string theory and with the right to do so because there is absolutely no evidence for their existences. They key to it is in your sentence, Stephan Hawking "feels" that it's true, even though there's no evidence confirming it either way. Besides, Stephan Hawking admitted he was wrong about wormholes through time, it's not like he's infallible.

Edited January 17, 2013 by SamBridge

[Gen1GT]

...it's not like he's infallible.

 

He 1up's me!

[SamBridge]

 

He 1up's me!

If you believe something just because he says it and not because there is evidence, you have violated one of his highest regards, which is science.

Edited January 17, 2013 by SamBridge

[Gen1GT]

If you believe something just because he says it and not because there is evidence, you have violated one of his highest regards, which is science.

 

Wha

What choice do I have? I'm a man in my late 30's with three children under five ... dropping my current career to pursue a PhD in physics is not in the cards right now.

 

It makes much more sense to trust the word of one of the most brilliant minds physics has ever seen; a person who is also a professor on the subject. Should all of his students take his teachings with a grain of salt?

 

Besides, we’re talking about theoretical physics, most of which is currently out of practical possibility to confirm with experimentation.

 

There is absolutely no way for me, personally, to confirm that a photon can be in two places at once, but as crazy as it sounds, I believe it. I also cannot test quantum entanglement. Others have, so I take them for their word also.

t choice do I have? I'm a man in my lates 30's with three children under five ... dropping my current career to persue a PhD in particle physics is not in the cards right now.

 

The structural foundation of science is the experimentation and results from those preceeding you. Their work cannot be disregarded because I'm expected to be skeptical to all new theories unless and until I can confirm with my own experimentation.

[swansont]

Swansont, if an electron can have zero velocity, does that mean we can put it on a box like a soccarball in a bathroom?

 

Put in a box? Sure, except that the box would have to be some kind of electromagnetic confinement, such as a Penning trap. Note that I said that zero is the lower limit of the speed, not the value of it.

[SamBridge]

 

Wha

What choice do I have? I'm a man in my late 30's with three children under five ... dropping my current career to pursue a PhD in physics is not in the cards right now.

Or you could at least google other possible theories, Stephan Hawking isn't the only smart person in the world. Smart people like Stephan Hawking don't care about image and power so much and they don't want people to believe what they say just because they say it, they want people to believe them because they find it holistically logical.

Edited January 17, 2013 by SamBridge

[Gen1GT]

Or you could at least google other possible theories, Stephan Hawking isn't the only smart person in the world. Smart people like Stephan Hawking don't care about image and power so much and they don't want people to believe what they say just because they say it, they want people to believe them because they find it holistically logical.

 

Although cosmology and astrophysics are different, there is nothing holistically logical about quantum physics. :s

[elfmotat]

there is nothing holistically logical about quantum physics. :s

 

It might be "strange" or "alien" or "unintuitive," but QM is certainly not "illogical."