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#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Unc, you got me on the second sentence:

"So, if a pair of say, electrons were "entangled" so that they had opposite spins, then sent flying in opposite directions"

I don't understand. Are we looking through a souped up electron microscope to see these entangled electrons? Can we see the opposite hands they fit (their opposite spins) and then we gently give them a shove in opposite directions?

Sorry. I am a scientist, but not a physicist. I stopped at Advanced Level Scholarship Level School Physics (which I passed). But that was long ago.

Since this is not happening on a macroscopic level, then there must be assumptions involved, and I guess, teeny side issues like division by zero, which seems to be a plague vide mathematics in science.

And, as I suggested, what about Heisenberg in this problem? We seem to be glibly measuring these particles, and knowing their past trajectories?

Sorry. Like others, I suspect, I am just trying to understand this "paradox".

Cat

#### Unclear Engineer

Regarding the apparent paradox, perhaps this explanation will help. Here

The last paragraph is interesting as it takes a Doppler approach. This is a little like the business analogy where “add-on” and “mark-up” differ. A 50% add-on to \$1 is \$1.50, but a 50% mark-up is \$2, allowing the seller to make 50% profit. [I think this applies.]

iPhone with rib sauce.

Helio, That is a really good pictorial explanation of the time difference effect for a round trip, as described by Special Relativity. This result is counter-intuitive, because it shows that a person would age less due to traveling fast, even though he ends up back at the starting point at zero velocity.

But, that in itself is not the "twin paradox" that people keep talking about. That twin paradox tries to use the idea or "relativity" to imply that a calculation done the same way for the twin who stays at the starting point should be considered to be moving in the other direction while the actual traveling twin is assumed to be at-rest. The problem with that is, as you have pointed out, the twin that is accelerated can be determined to be different from the twin that remains at rest because the forces involved are detectable, and while they are being applied, violate the condition of Special Relativity that it applies to observations between two inertial frames of reference. I agree with that, but the problem is that the calculation does not include the effects of the accelerations on the mathematical result.

So, we are left in the situation where we agree that the Theory of Special Relativity cannot be applied to this whole experiment without modification, but we do not have the formula that we think does apply to the whole experiment. That is what leaves in-doubt that veracity of the result.

However, I seem to remember that some experiments were done by putting clocks in orbit around the Earth, and comparing them to clocks left on earth once the orbiting clocks were returned to Earth, and that those experiments verified the time difference calculated by "relativity". Unfortunately, that would involve both Special and General Relativity, and the media reports that I remember were not really adequate to describe the details of the experiment.

But, we currently use those theories to make verifiable predictions with our satellite GPS systems. See https://www.astronomy.ohio-state.edu/pogge.1/Ast162/Unit5/gps.html . That says Special Relativity makes the clocks in the GPS satellite orbits seem to run 7 microseconds per day slower than our clocks here on Earth's surface, but General Relativity says that clocks here on Earth's surface should run 45 microseconds per day slower than the clocks in orbit because of the difference in the gravitational field force at the two different altitudes. The net effect is that the clocks on the GPS satellites need a 38 microsecond per day correction to avoid the calculated positions on Earth shifting by 10 kilometers per day! That does seem like good experimental validation of the theories, as applied together, for observations of things in 2 different locations.

But, that is really not represented by the out-and-back time lines in your example, because the distance between the sender and receiver is not being monotonically increased and decreased by the velocity in orbit. So, I am having a hard time thinking about it as vectors. The Special Relativity part is really a scalar calculation, so it seems to work no matter what direction(s) the travel is going in, compared to the observer.

The problem is that an orbit is not an inertial frame of reference. It is a constant acceleration frame of reference with the acceleration vector changing the direction of travel along the constantly shifting radial direction (relative to an actual inertial frame of reference).

So the same criticism (motions of subjects not always being in inertial frames of reference) that applies to the "twin paradox" seems to also apply to this experimental verification for Special Relativity. It seems inconsistent to use the same concept in 2 diametrically opposite ways, logically.

So, I am still looking for a pure empirical demonstration that a clock that is sent into orbit and returned to Earth has actually shown less time passage than a clock left on Earth when the difference is corrected for the altitude effects of General Relativity.

Because that seems like an experiment that can be done, I expect that it has been done. I just have not found it, yet. This link https://en.wikipedia.org/wiki/Time_dilation talks about experimental verifications using things like sub atomic particle half-life measurements. It also claims a solution to the twin paradox with Minkowski diagrams, but I am not following that clearly, (yet?).

Catastrophe

#### Helio

But, that in itself is not the "twin paradox" that people keep talking about. That twin paradox tries to use the idea or "relativity" to imply that a calculation done the same way for the twin who stays at the starting point should be considered to be moving in the other direction while the actual traveling twin is assumed to be at-rest.
Yes, we assume relativity should work from the view of any inertial frame, but....

The problem with that is, as you have pointed out, the twin that is accelerated can be determined to be different from the twin that remains at rest because the forces involved are detectable, and while they are being applied, violate the condition of Special Relativity that it applies to observations between two inertial frames of reference. I agree with that, but the problem is that the calculation does not include the effects of the accelerations on the mathematical result.
I don't see a violation during acceleration, though I'm no expert. Acceleration involves GR, but SR can work fine by doing the math for incremental increases in velocity. The key is that only one person is experiencing acceleration and, somehow, time dilation gets assigned to this person (ie traveler). [Perhaps some see this event as some sort of symmetry break.] The math during acceleration (& deceleration) will show that there is very little time dilation during acceleration. The real time dilation (or length contraction if one wishes) is in the long travel times at relativistic speeds.

So, we are left in the situation where we agree that the Theory of Special Relativity cannot be applied to this whole experiment without modification, but we do not have the formula that we think does apply to the whole experiment. That is what leaves in-doubt that veracity of the result.
I'm saying SR can be made to work effectively even during the brief time period of accelerations. I suspect the math will show very little time dilation difference in accounting for acceleration for those long trips, if one wants to do the slice -method of SR.

However, I seem to remember that some experiments were done by putting clocks in orbit around the Earth, and comparing them to clocks left on earth once the orbiting clocks were returned to Earth, and that those experiments verified the time difference calculated by "relativity". Unfortunately, that would involve both Special and General Relativity, and the media reports that I remember were not really adequate to describe the details of the experiment.
Correct.

But, we currently use those theories to make verifiable predictions with our satellite GPS systems. See https://www.astronomy.ohio-state.edu/pogge.1/Ast162/Unit5/gps.html . That says Special Relativity makes the clocks in the GPS satellite orbits seem to run 7 microseconds per day slower than our clocks here on Earth's surface, but General Relativity says that clocks here on Earth's surface should run 45 microseconds per day slower than the clocks in orbit because of the difference in the gravitational field force at the two different altitudes. The net effect is that the clocks on the GPS satellites need a 38 microsecond per day correction to avoid the calculated positions on Earth shifting by 10 kilometers per day! That does seem like good experimental validation of the theories, as applied together, for observations of things in 2 different locations.
Yes, SR and GR dilations work against one another to produce the 38 microsecond delay.

Many other experiments support relativity. The muon story is a common one used. The muon should never have time to reach our surface, but relativity demonstrates, accurately, what actually happens. [Oddly, the story is told in terms of length contraction rather than time dilation. There is very little evidence that length contraction is "real", but I did learn of one likely demonstration.]

But, that is really not represented by the out-and-back time lines in your example, because the distance between the sender and receiver is not being monotonically increased and decreased by the velocity in orbit.
You are referring to the Doppler point of view as noted in that link, no doubt. I have not given that view a lot of thought, but there must be something to it because the traveler must necessarily receive the same no. of radio pulses as those sent, but the difference is the rate they are received. There will be a blueshift/redshift difference by the link's simple math shown, apparently.

The problem is that an orbit is not an inertial frame of reference. It is a constant acceleration frame of reference with the acceleration vector changing the direction of travel along the constantly shifting radial direction (relative to an actual inertial frame of reference).
That's a good point because that too involves GR. I'm curious if the simplified method (slicing velocity units) for SR is used.

So the same criticism (motions of subjects not always being in inertial frames of reference) that applies to the "twin paradox" seems to also apply to this experimental verification for Special Relativity. It seems inconsistent to use the same concept in 2 diametrically opposite ways, logically.
Only when all the relativistic effects are included will the result match the experimental result. I don't understand it that well, admittedly, since it isn't intuitive in the slightest.

This questioning is (or was) common. There were 100 prominent Germans (authors and at least one scientist) that sent a letter out stating Einstein's relativity was wrong. Einstein was shown this letter and his response was that why would you need 100 when only 1 is necessary (falsifying the theory).

So, I am still looking for a pure empirical demonstration that a clock that is sent into orbit and returned to Earth has actually shown less time passage than a clock left on Earth when the difference is corrected for the altitude effects of General Relativity.
Some of the many experiments include the wavelength shift for light when pointed from a higher elevation towards the ground. Even when done at extreme precisions, relativity, and nothing else, shines.

I've tried to think of SR using the analogy of a boat at a high speed. Speed racing often only has the prop in the water as the hull no longer is emersed in water creating wake. If relativistic speeds of a spacecraft traveling faster and faster were to skip over more and more Planck time pulses (just like the boat over fewer and fewer waves of water), then we would have a more intuitive solution. Unfortunately, this idea is incorrect, though I still like it since it can assume the Hubble Flow is the ocean.

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#### Pogo

Cat:
1. I thought all electrons have a spin number of 1/2, no matter its orientation.
2. Electron microscopes don't look at electrons, they use electrons to bounce off and create images of other small stuff.

But, somehow, I have a sneaking suspicion that you knew all that!

Catastrophe

#### Pogo

The bartender tells the tachyon before he arrives,
Werner Heisenberg was stopped by a police officer for speeding, Werner said 'Well, if you knew where I was when I was driving, you could not possible know how fast I was going.'

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Pogo,
"Are we looking through a souped up electron microscope to see these entangled electrons? Can we see the opposite hands they fit (their opposite spins) and then we gently give them a shove in opposite directions?" Shhhhh. It was a rhetorical question.

Cat

Pogo

#### dave123

How, I have never seen anything like this in my life.

One joke that I didn't understand until reading an explanation several posts later and this thread had its own big bang.

I got good grades in college, but you gentlemen are so far beyond me that I feel stupid just reading your posts.

At the end of the day, I really appreciate you all helping me. I'm still stuck figuring a way to make light cease to exist, by a virus or otherwise, or my whole story will need a major overhaul.

I need something that a human inadvertently does to cause a delayed reaction in a being composed primarily of light. It does not have to be supported by current knowledge of the universe, but should be somewhat believable by the masses (not that masses will ever read my story).

Luckily, that part is further than my current stage of writing, and I do like Cat's earlier suggestion about light waves being absorbed, but I'm pretty sure that would be immediate and I need a delayed reaction. The search continues

Oh, about getting the beings to travel faster than light, perhaps I will revert to something like warp drive or hyperspace..

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
You could try having your being made of light of a particular frequency (such as colour). You could arrange a gadget - designed or accidental - which changes the light to uv or ir. Tell us what properties you need. The being, changing 'colour=frequency' could cease to exist, being changed in to a different frequency. Then this frequency could pass through matter (like neutrinos) and dissipate. I can't think right this minute how to do that. Stretching it a bit, perhaps the light energy could pass through a 'black (magic) box' which turned the light energy into neutrinos, which just dissipated away. Light being would be a 'gonna' though. No reconstruction.

Cat

dave123

#### dave123

Amazingly, Cat, I understood that post. Either I'm getting better, or you are good at explaining things. You have been quite a bit of help; I can see it now - readers of my story will wonder why I dedicated it to an unspecified Catastrophe that helped in its creation.

Anyway,
For my story, as planned, to work, my "light being" will enter a human spaceship through a window then depart. I would need the light being to be somehow contaminated, or changed, in such a manner that it is destroyed. The being must survive for a time after exposure and not be aware of its pending doom. Oh, this is important; the being must be able to somehow "infect" another light being so that it too is destroyed.

Tall order, I know. Perhaps the light being could appropriate an object that would seemingly be innocuous, and then introduce said object into its native environment, thereby destroying any light beings that witness its unveiling?

#### Phillip Huggan

A probe accelerates using VASIMR, Ions with metalensing, Photon propulsion, ORION, whatever...
Now its cargo is subject to GR. Its cargo is radio-active samples that decay fast. You shoot each particle at a giant imaging sheet in space. The ones you send out a decent fraction of c will age more slowly and be more redioactive hitting the sheet behind the first one. The ones you send at a slower pace will of course lose more radiation, but they will only last a millionth longer than if they weren't shot sideways from the probe and given SR.

#### dave123

A probe accelerates using VASIMR, Ions with metalensing, Photon propulsion, ORION, whatever...
Now its cargo is subject to GR. Its cargo is radio-active samples that decay fast. You shoot each particle at a giant imaging sheet in space. The ones you send out a decent fraction of c will age more slowly and be more redioactive hitting the sheet behind the first one. The ones you send at a slower pace will of course lose more radiation, but they will only last a millionth longer than if they weren't shot sideways from the probe and given SR.
And I'm stupid again as I can only guess at what your suggesting to solve my problem(s).

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Dave, OK, let's split it up:
1. "light being" will enter a human spaceship through a window then depart.
Does it need to depart? Can it 'die' n the spaceship?

2. light being to be somehow contaminated, or changed, in such a manner that it is destroyed.
Again, can it be destroyed in the ship?

3. The being must survive for a time after exposure and not be aware of its pending doom.

4. important - the being must be able to somehow "infect" another light being so that it too is destroyed.
Same question. Is the second being in the ship, or outside -so, obviously, 1st LB must leave.

Cat

dave123

#### Phillip Huggan

And I'm stupid again as I can only guess at what your suggesting to solve my problem(s).
Sry, I forget the point is to make a closed time curve to erase the initial entanglement from one of its future entangled brethren. Could the being be composed of light in an entangled state? The person could do something to decohere some or all of its body/equipment by interacting with the photons it was entangled to. An entangled actor would need to be at UHV near absolute zero, their clothes or equipment could insulated them...

#### dave123

My being must survive without realizing it has been "infected" long enough for it to get home (undefined length of travel time) and inadvertanly "infect" another being that was not along for the trip.

This question and the question of how long to Neptune from earth are my 2 stumbing blocks.

#### dave123

Sry, I forget the point is to make a closed time curve to erase the initial entanglement from one of its future entangled brethren. Could the being be composed of light in an entangled state? The person could do something to decohere some or all of its body/equipment by interacting with the photons it was entangled to. An entangled actor would need to be at UHV near absolute zero, their clothes or equipment could insulated them...
This clarification does help. Thank you for your input. Please see my prior post to see if this would still be viable. I saw info concerning entanglement during the post joke Tachyon discussion. I'm off to read that part again. I think the key is that the being must survive for a period of time..

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Phillip, is entanglement possible on large 'structures' even if made of light?
Or,
is it like 'wormholes' which might allow passage of a subatomic particle, but not USS Enterprise?

Cat

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Dave, OK, let's split it up:
1. "light being" will enter a human spaceship through a window then depart.
Does it need to depart? Can it 'die' n the spaceship?

2. light being to be somehow contaminated, or changed, in such a manner that it is destroyed.
Again, can it be destroyed in the ship?

3. The being must survive for a time after exposure and not be aware of its pending doom.

4. important - the being must be able to somehow "infect" another light being so that it too is destroyed.
Same question. Is the second being in the ship, or outside -so, obviously, 1st LB must leave.

Cat
From dave:
My being must survive without realizing it has been "infected" long enough for it to get home (undefined length of travel time) and inadvertanly "infect" another being that was not along for the trip.

Dave, that complicates it. I had it solved (I think) provided 1st LB died in, or close to, the ship. You couldn't have 2nd LB outside, but close by, could you?
In either case, can 1st LB start dying slowly, without realising it?

Cat

dave123

#### Phillip Huggan

A being will probably die within months with our current technology on Earth. If the whole is made of the equivalent of a string of future aerogels, it might not interact with anything else, much. But one quantum interaction decoheres it. But if each entanglement of a dust mote size of its CNS is separate, it could be considered analogous to how our brain renews itself over time. Vacuum is thought to decay entanglement over weeks/months, but it might be made to be insulated from vacuum fluctuations. An order of magnitude or so fewer vacuum fluctuations may preserve a body with a Quadrillion separate entangled systems, for a mammal life-span...

dave123

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Well, it is science fiction . . . . . . . . .

Cat

#### Unclear Engineer

Perhaps this will provide some scientific "cover" for the desired fiction.
See https://scitechdaily.com/mit-physic...etecting-gravitational-waves-and-dark-matter/ .

The entanglement and disentanglement processes with different frequencies of lasers and the "time reversal" element of the Hamiltonian discussion might give you enough leeway to make up something that sounds plausible. This paper is about atoms, but photons can be entangled, too. And, I would expect a "being" composed entirely of photons must be in some extremely complicated state of entanglement that can respond to macroscopic phenomena without losing the entanglement, even with changes to energy states.

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dave123

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Quantum Entanglement Has Now Been Directly Observed at a Larger Macroscopic Scale. Quantum entanglement is the binding together of two particles or objects, even though they may be far apart – their respective properties are linked in a way that's not possible under the rules of classical physics.

Quantum Entanglement Has Now Been Directly Observed at a ...

It's a weird phenomenon that Einstein described as "spooky action at a distance", but its weirdness is what makes it so fascinating to scientists. In new research, quantum entanglement has been directly observed and recorded at the macroscopic scale – a scale much bigger than the subatomic particles normally associated with entanglement.

The dimensions involved are still very small from our perspective – these experiments involved two tiny aluminum drums one-fifth the width of a human hair – but in the realm of quantum physics they're absolutely huge.

Cat

#### Unclear Engineer

For a fictional plot involving a being made out of photons that needs to be killed remotely after leaving the human space ship, how about the humans using lasers to insert entangled photons that the humans can control, so that, when perturbed by the humans at their end of the entanglement, the being is disrupted and becomes unentangled internally, so "dies", which could be illustrated as its component photons flying away from the being and the being dissipating into nothing?

As for having that be "contagious" to other light beings, how about hypothesizing that the light beings are all entangled with each other, perhaps as a result of how they reproduce, and that disentangling one disrupts the entanglement with the others in such a way that their own internal entanglements are also disrupted, and they too die of their photons dissipating?

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Unc,
Congratulations! Those are really clever ideas. However, I do think that is stretching 'entanglement' to the limit.

But, who cares? They are really clever ideas, and it is for fictional purposes.

I have not checked to see if they meet all the criteria.

Cat

P.S.
3. The being must survive for a time after exposure and not be aware of its pending doom.

This is the only one I am not sure of. what do you think?

#### Unclear Engineer

As for #3, I was trying to address that with the being getting an addition of entangled photons intentionally inserted by humans, so that humans could control when they use their end of the entanglement to kill the photon critter well after he departs from their space ship. Not quite the same as a "light virus", but as close as I can come.

If the fictional script requires that the humans not know they have done this, then maybe the light guy could accidentally step into some sort of an astronomical laser interferometer and just happen to get "infected" with some entangled photons that the humans later alter, either intentionally (because they figured out how the being "lives" and want to disrupt it), or maybe as pure good luck that they did maintenance in their laser gizmo and it just happens to kill off an impending existential threat to all humanity.

I really don't know what the intended script is, so just offering some ideas.

Given how poorly we understand entanglement, and the clear need for any being that is composed completely of photons needing to have those photons behave in coordinated manners, it seems to me that stretching entanglement is a major requirement of the scenario to begin with. So, just stretch it into whatever form that suits the intended script.

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