# NASA's Psyche spacecraft just fired a laser 10 million miles away in deep space

#### Classical Motion

I wonder how much that laser spot grew in 10 million miles.

Now we can download much faster. But we still have 30 yr old data no one has seen yet.

Perhaps A.I. can help with this.

#### billslugg

Beam divergence is limited by diffraction. Divergence angle in radians = wavelength divided by (pi times beam diameter).

The beam is "near infrared" which runs from 860 nm up to 2500 nm. I can't find the exact wavelength but on a graph I could see that at 860 the Earth's atmosphere is 100% transparent, no so for the entire rest of the band.

The laser beam coming from the spacecraft is 20 cm in diameter and the distance right now is 16 million km.

At 16e6 km the beam width would be 219 km.

This is why they are using the Hale telescope on Mt Palomar to receive the data.

Helio

#### Classical Motion

Thank you. I had no idea the beam was that large.

I'm sure it will improve and give us higher transfer rates. But we will still have the delay.

We need some kind of "space shaft", to connect instant motion at both ends.

#### billslugg

Any solid shaft depends upon electromagnetism between atoms, as one outer shell electron presses against a neighboring outer shell electron. The movement of a sold shaft cannot be any faster than the speed of light.

#### Unclear Engineer

Seems like the only way to get faster communication would be to really master the ability to use entanglement. Not sure we will ever get that working for us.

#### Classical Motion

I think a rotating shaft has a quantum condensate property. Not all condensate properties, but it has the same spacetime thru out it's structure. A singularity sorta. In a time and motion sense.

A twist on one end, gives the same instant twist on the other end.....at a distance. And all along the distance. A space time synchronizer.

Unlike gases and liquids, the metal solid has locked and fixed bonding structures. Even in Ag, the vast majority of electrons are locked and bonded. And I think there is more to just electron sharing involved with solids. The atomic EM fields have shapes and densities and fit, and not fit, halfway fit, due to these structures.......sorta like locks and keys. Shape fit bonds.

If there were a shaft between here and the moon, I believe a twist would have no delay. A push might take a delay, but I don't think a twist would. And I don't believe a change in the twist would delay either. But no one else thinks this way and I know of no way to try it.

But rotating shafts provide this function with mechanical analog computers. Or any timed or ratio-ed motion.

Too bad we can't lock and align space like that.

#### Unclear Engineer

I don't understand why you think that a solid shaft moves without distortion when subjected to torque. Have you ever turned the head off of a screw by trying to turn it into something the is providing too much resistance? And the same with longitudinal forces, which create waves that travel at the speed of sound in the material. Just listening to a bell ring should tell you that the whole object does not move as a single, undeformable part when struck at one point on its surface. Solids do not behave like you posted. They deform and can spring back, stay deformed or even break when forces are applied.

#### billslugg

Entanglement cannot be used to transmit information. The reason is that the sender has no way of choosing the quantum state of the particle. The receiver can look at their particle and know what the sender's quantum state was. They could use this to coordinate activities thus qualifies as "information". Problem is, that information did not travel at the speed of light, it traveled in the space traveler's vehicle to get to the destination at less than the speed of light.

#### billslugg

A solid shaft made of pure diamond has a speed of sound of 18,350 meters per second. To communicate with the Moon, it would take 11.6 hours to get an answer. To the Sun and back is 378 days. To the nearest star 138,000 years.

#### Classical Motion

Oh, I have seen solid distortion. But what I have seen takes a certain level of force to distort. And I understand sound propagation and the distortion of solids with it. And have used E fields to distort solid structures. But it seems distortions take certain stimulation levels and stimulation rates for it. I understand temp causes distortion too. Are we now saying any force and any motion causes distortion in solids? I was not aware of that.

So the concept of a solid is not strictly a solid. A solid can not be accelerated without distortion? So one end of the shaft is distorted and has a delay in the torque applied from the other end? A delay in the twist. The twist takes time to reach the other end.

Can you measure this?

#### Unclear Engineer

Bill, I think there are people working on the idea of transmitting information with entanglement. But, like any communication device, you need to first take the device to both ends of the intended communication chain, So, it seems that some people are thinking that they can transport entangled items to some separation, then make a decision at one end that gets reflected instantaneously at the other end.

Personally, I am not fully convinced that entanglement behaves as it is portrayed by either the scientists nor the media. They like to quote Einstein about "spooky action at a distance". If that is really what it is, then if we could control it, it would seem that we could transmit information instantaneously with it. That is a big "IF" to my thinking. But it seems to be what some people are thinking, which is why I mentioned it - with an "if" attached.

#### billslugg

Yes, I know lots of people are looking at it with an eye for using it to communicate, but they are all going to fail because our current laws of physics say it can't be done. Every scheme has a fatal flaw in that the sender has no way of controlling what state his photon settles at. Any effort to control it ruins the entanglement. If you don't control the sending photon state, the information you get at the far end got there not faster than the speed of light but however fast it was you carried the photon there. Yes, information, no - not faster than c. Going to have to negate a few laws of physics on this one.

Entanglement is not a theory, it has been demonstrated many times. There are many machines using it right now. And not just photons have been entangled, subatomic particles and even tiny diamonds have been entangled.

#### Unclear Engineer

I don't doubt that quantum things get entangled. But, that is not the same as "spooky action at a distance".

If you make a left shoe and a right shoe and put one in a sealed box and send it to Mars, the receiver on Mars knows that the other one of the pair that is still on Earth must be the opposite of what he finds in the box when he opens it. But, that is not action at a distance. And the information did not travel any faster than the shoe. Same thing if you send one of a pair of entangled photons, electrons or whatever to Mars. It is the speed with which that thing traveled to Mars that is the speed of the information transfer.

So, to me, "spooky action at a distance" requires that the person on Earth be able to modify the shoe left on Earth to be a right or left, at his discretion, and have the shoe on Mars immediately become the opposite when the box is opened before any light has had time to travel between Earth and Mars.

That would certainly be "spooky", even if done with photons instead of shoes. However, there was Nobel Prize given just a little while ago to some scientists who supposedly disproved this left shoe / right shoe explanation of what entanglement really is. See https://www.scientificamerican.com/...ntanglement-win-2022-nobel-prize-in-physics1/ . I don't really understand Bell's Test well enough to agree or disagree with those guys about what they proved. But, I recognize that they think they proved "spooky action at a distance" is real.

#### billslugg

Right, Bell's Test proved that the information is not traveling with the object to the far end, only to be looked at later. The photon at the sending end chooses one quantum state randomly and that information is sent to the distant half which is found to be in the other state. So, in a sense, it is "spooky action at a distance". But there is no way you can massage this to send a message from one end to another. The sender never has a choice in what the state is. There is no way to send information to the other end.
Say the traveller goes to the nearest star and wants to inform Earth instantly that it is inhabited. The person can go ahead and determine the state of his photon and the guy on Earth would instantly know what that state was but what good is it? It was a random message.

#### Classical Motion

We don't need to know the state of entanglement to use it. Because it's instant. Huh?

Lets take a string or bunch of particles, or what ever, entangle them, divide them, send half to Mars.

Measure one on Mars. One on earth flips. Measure another one on mars. Another on earth flips. These are instant actions. And we can set the rate. We can use the rate as a carrier. We can encode a fast rate, on top of a higher rate carrier. The rate of an instant carrier.

But how high can we sequence a measurement of entanglement?

The switching of an instant event. Another problem to work out.

#### billslugg

The guy on Earth cannot just watch a photon to see when it flips. He does not know what the state of the photon is until he measures it. When he measures it he does not know if he was the one who decohered it or if the guy on Mars had triggered it. Again, no possibility of using timing to send a message.

#### Classical Motion

Pardon me. I thought we could detect the change in one condensate, while measuring the other state. Not knowing the states of either. But could detect the change.

#### Questioner

What if you had a bunch of entangled photons and the information was passed by precisely which photons you chose to decohere?
decohereing photon one means the planet is inhabited and decohereing photon two means it's uninhabited.

You could communicate in binary code as long as you didn't mind burning through precious entangled pairs that were pre- delivered to both ends of the connection.

decoherence is a one & (retained) coherence is a zero.
perhaps initiated with a one/decoherence to know the length of a message that was up address of that terminator.

#### Questioner

Since they would be a precious commodity you could send a signal that indicated the message would be using only the still coherent pairs of previous messages.

#### Questioner

Or maybe that would be standard,
that up address coherennt pairs would be the start of any new message.
That would maximize efficiency.

#### billslugg

With a bunch of entagled photons stashed at each end we can only do one thing: Grab a photon and examine what its quantum state is. We grab photon #1, open it up, look at it and it is an "up" photon. This tells us for a fact that the photon at the other end is a "down" photon. What we don't know is: Am I the one who fixed the system by examining one of the photons, or did the other guy examined his first, which set mine at a particular state?

You cannot sit there looking at an entangle photon and suddenly one day you see it change. That is not how it works. You cannot tell anything about the photon until you measure it. The act of measuring it freezes it into one state, selected at random. Only you don't know if you just did it or if the other guy did it first which set the state of yours, so that when you went to look at it, it was not you but the other guy.

Again, we have instant communication of something that does us no good. We can't select what message to send. The receiver does not know when it was sent or even if it was sent.

#### mond8

Article states "taking with ground control". I believe "talking" is what was meant.

#### Homer10

The rumors are that the calculated density (and that is very hard to figure out exactly) is very close to the density of Gold. It this thing turns out to be an actual huge chunk of Gold, I fear a huge race to grab as much of this (or remotely claim it as theirs) as possible. I fear a huge human folly powered by greed. Even if it isn't Gold, it could have other very valuable metals, again triggering greed. Well, we'll all know in time. Oh, BTW. The thing is 500,000,000 miles away. Not very close at all, between Mars, and Jupiter.

#### Unclear Engineer

This info transmission discussion so far seems to depend upon what is supposedly disproved with passing Bell's Test. That is, that there is some way to show that pairs of widely separated entangled photons do actually cause one to change (or at least fall into a fixed) state when the other is observed. The test supposedly shows that it is not just a matter of the other one being in the other state, already, just waiting to be observed as such.

As I posted before, I am not sufficiently knowledgeable about Bell's Test to agree or disagree with what these scientists and the Nobel Committee believe it shows.

And, I do see the problem that Bill posts about not being able to send information with the phenomenon. I just can't reconcile the two concepts. How can we prove that information is being sent instantaneously between 2 photons when we still believe that we can't send information spontaneously between 2 photons? Bell's test supposedly proves that the "already paired" explanation that would not require instantaneous information exchange is not true.

To me, the other, more intuitively plausible explanation is that the quantum mechanics assumption about superposition of single objects in multiple states is not true. But, no quantum mechanics expert is going to give up that assumption without a much bigger fight.

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