Re: The grandfather paradox, redux
On Sunday, March 24, 2019 at 3:48:30 AM UTC-5, Philip Thrift wrote: > > > > cf. https://en.wikipedia.org/wiki/Grandfather_paradox > > > In the usual EPR-type experiment, a particle A is sent westward and > "correlated" particle B is sent eastward. (A could travel 5 miles and B > could travel just 5 feet, for example.) But their detection outputs show > that A and B are "entangled" so that apparently the detection setups at > both ends influences the "final" states of A and B. > > > In another EPR-type experiment, an emitter sends one particle A "skyward" > into space, and simultaneously a twin particle B to a detector nearby. > Depending on what the B detector measures, an unlucky grandfather is killed > or not. The A particle bends around a massive object (its path bent by > general relativity - it could also be more than one massive object involved > in its travel) light years away and returns to Earth 30 years later when > that grandfather's grandchild has set up a detector for A whose measurement > results in the grandfather's death. > > > - pt > > I should add that the difference in the above example from the typical one A-detector <- Source -> B-detector A B is that in the typical example the time of travel A and the time of travel of B are fairly equal (though both very short), but in the above example the time of travel of A is decades, while B stays the same. - pt -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: The grandfather paradox, redux
I always liked Deutsch's version of MWI better. You kill Gramps but not in your own universe.I also liked Trans-Earth's trading or warfare. Maybe trade, and forget the war? We could do trade with other successful human species like worlds where Neanderthals or Boskops hit the bigtime?Alternate Earth's vacations might be fun, dating? -Original Message- From: Philip Thrift To: Everything List Sent: Sun, Mar 24, 2019 4:48 am Subject: The grandfather paradox, redux cf. https://en.wikipedia.org/ wiki/Grandfather_paradox In the usual EPR-type experiment, a particle A is sent westward and "correlated" particle B is sent eastward. (A could travel 5 miles and B could travel just 5 feet, for example.) But their detection outputs show that A and B are "entangled" so that apparently the detection setups at both ends influences the "final" states of A and B. In another EPR-type experiment, an emitter sends one particle A "skyward" into space, and simultaneously a twin particle B to a detector nearby. Depending on what the B detector measures, an unlucky grandfather is killed or not. The A particle bends around a massive object (its path bent by general relativity - it could also be more than one massive object involved in its travel) light years away and returns to Earth 30 years later when that grandfather's grandchild has set up a detector for A whose measurement results in the grandfather's death. - pt -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: Quantum Tunneling
On Saturday, March 23, 2019 at 7:59:40 AM UTC-6, John Clark wrote:
>
> On Thu, Mar 21, 2019 at 7:46 PM Lawrence Crowell > wrote:
>
>
>> *> The wave function for a plane wave e^{ikx} has the phase ikx for k =
>> 2πp/h, h = Planck's constant, is then real and the total phase ikx - iEt
>> then means time is imaginary valued as well. [...] The imaginary part is
>> not time we measure with clocks and so tunneling has no meaning with
>> respect to that definition of time.*
>
>
> The trouble is, to get some sort of intuitive physical understanding of
> Quantum Tunneling, as opposed to a purely mathematical understanding, it is
> necessary to make a connection between the thing we measure with a clock
> and the thing we wish to understand. This is how I think about it, I'm sure
> it's not exactly correct but let me know if it's at least approximately
> right or if you know of another way that is less wrong:
>
> If I want to send you a electron as a message (attack at dawn for example)
> and speed is important I can't use Quantum Tunneling to send it to you
> faster than light because only the successful attempts are instantaneous.
> If you're on the other side of an energy barrier and I don't have enough
> energy to get through it most of my attempts to send you an electron will
> be unsuccessful. And the probability of the electron getting through drops
> exponentially with the width of the barrier. Thus although my very rare
> successes will be instantaneous if you take into account all my failed
> attempts then the time between my desire to send you a message and the time
> you receive it will always be longer than if I forgot about Quantum
> Tunneling and just flashed a old fashioned low tech beam of light at you
> instead.
>
> John K Clark
>
The statistical set on the occurrence of the particle will have its average
or mean at the velocity of the wave. The appearance of the particle on the
other side of the barrier is no different than finding there is a
stochasticity to the appearance of the particle at points in free space.
The only difference is that the exponential decay of probability through
the tunneling barrier will mean it has less occurrences on the other side.
Where the particle occurs in space is the result of a statistical
distribution, and the reduction of the wave packet makes its occurrence at
some point evident.
LC
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
The grandfather paradox, redux
cf. https://en.wikipedia.org/wiki/Grandfather_paradox In the usual EPR-type experiment, a particle A is sent westward and "correlated" particle B is sent eastward. (A could travel 5 miles and B could travel just 5 feet, for example.) But their detection outputs show that A and B are "entangled" so that apparently the detection setups at both ends influences the "final" states of A and B. In another EPR-type experiment, an emitter sends one particle A "skyward" into space, and simultaneously a twin particle B to a detector nearby. Depending on what the B detector measures, an unlucky grandfather is killed or not. The A particle bends around a massive object (its path bent by general relativity - it could also be more than one massive object involved in its travel) light years away and returns to Earth 30 years later when that grandfather's grandchild has set up a detector for A whose measurement results in the grandfather's death. - pt -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: Questions about the Equivalence Principle (EP) and GR
On Saturday, March 23, 2019 at 2:19:39 PM UTC-6, Brent wrote: > > > > On 3/23/2019 5:45 AM, agrays...@gmail.com wrote: > > > > On Thursday, March 21, 2019 at 12:40:13 AM UTC-6, smitra wrote: >> >> On 21-03-2019 06:21, agrays...@gmail.com wrote: >> > On Wednesday, March 20, 2019 at 12:51:18 PM UTC-6, Brent wrote: >> > >> >> On 3/20/2019 3:07 AM, agrays...@gmail.com wrote: >> >> >> >> On Tuesday, March 19, 2019 at 7:23:29 PM UTC-6, Brent wrote: >> >> >> >> On 3/19/2019 9:32 AM, John Clark wrote: >> >> >> >> On Tue, Mar 19, 2019 at 4:50 AM wrote: >> >> >> >>> I SUPPOSE EINSTEIN STARTED WITH THE MOTIVATION OF FINDING A >> >> GENERAL TRANSFORMATION FROM ONE ACCELERATING FRAME TO ANOTHER, AND >> >> LATER GAVE UP ON THIS PROJECT AND SETTLED FOR A THEORY OF GRAVITY. >> >> IS THIS TRUE? TIA, AG >> >> >> >> Einstein's breakthrough, what he called "the happiest thought of my >> >> life" was when he realized a man in a falling elevator will not feel >> >> gravity but a man in a accelerating elevator will. In other words an >> >> accelerating frame and gravity are the same thing, that's why it's >> >> called the Equivalence Principle. >> > >> > I wonder if Einstein ever considered whether a charged particle in >> > the falling radiate would radiate? >> > >> > Brent >> > >> > Because of your typos, at first I thought you were joking. Well, maybe >> > it was a joke, but for me it sounds like a damned good question. I >> > surmise that a charged particle accelerating due to gravity does NOT >> > radiate energy, but why? AG >> > >> > Sorry about the typos. Yes, it does seem paradoxical. Here's a >> > paper that purports to solve the problem. >> > >> > THE RADIATION OF A UNIFORMLY ACCELERATED CHARGE IS BEYOND THE HORIZON: >> > A SIMPLE DERIVATION >> > >> > Camila de Almeida [1], Alberto Saa [2] >> > (Submitted on 6 Jun 2005 (v1 [3]), last revised 2 Dec 2005 (this >> > version, v5)) >> > >> >> We show, by exploring some elementary consequences of the covariance >> >> of Maxwell's equations under general coordinate transformations, >> >> that, despite inertial observers can indeed detect electromagnetic >> >> radiation emitted from a uniformly accelerated charge, comoving >> >> observers will see only a static electric field. This simple >> >> analysis can help understanding one of the most celebrated paradoxes >> >> of last century. >> > >> > Comments: >> > Revtex, 6 pages, 2 figures. v2: Some small >> corrections. v3: >> > Citation of a earlier paper included. v4: Some stylistic changes. v5: >> > Final version to appear in AJP >> > >> > Subjects: >> > Classical Physics (physics.class-ph); General >> Relativity and >> > Quantum Cosmology (gr-qc) >> > >> > Journal reference: >> > Am.J.Phys. 74 (2006) 154-158 >> > >> > DOI: >> > 10.1119/1.2162548 [4] >> > >> > Cite as: >> > arXiv:physics/0506049 [5] [physics.class-ph] >> > >> > (or arXiv:physics/0506049v5 [6] [physics.class-ph] for >> this >> > version) >> > >> > And another paper that looks at possible experimental evidence. >> > >> > ELECTRICAL CHARGES IN GRAVITATIONAL FIELDS, AND EINSTEINS >> > EQUIVALENCE PRINCIPLE >> > >> > Gerold Gründler [7] >> > (Submitted on 14 Sep 2015 (v1 [8]), last revised 12 Oct 2015 (this >> > version, v3)) >> > >> >> According to Larmor's formula, accelerated electric charges radiate >> >> electromagnetic waves. Hence charges should radiate, if they are in >> >> free fall in gravitational fields, and they should not radiate if >> >> they are supported at rest in gravitational fields. But according to >> >> Einstein's equivalence principle, charges in free fall should not >> >> radiate, while charges supported at rest in gravitational fields >> >> should radiate. In this article we point out indirect experimental >> >> evidence, indicating that the equivalence principle is correct, >> >> while the traditional interpretation of Larmor's formula must be >> >> amended. >> > >> > Subjects: >> > General Physics (physics.gen-ph) >> > >> > Cite as: >> > arXiv:1509.08757 [9] [physics.gen-ph] >> > >> > (or arXiv:1509.08757v3 [10] [physics.gen-ph] for this >> version) >> > >> > However, I don't find them entirely convincing. We know that double >> > stars, which are orbiting one another in free-fall, radiate >> > gravitational waves. Are we to suppose that if one or both of them >> > had an electrical charge that there would be no EM radiation? >> > >> > Brent >> > >> > IF WE GO BACK TO CLASSICAL E, WHERE DOES THE EM RADIATION COME FROM >> > WHICH IS EMITTED FOR ACCELERATING PARTICLES? IT CANT COME FROM >> > THE SELF FIELD OF, SAY, AN ELECTRON, SINCE THAT WOULD
