Could we “cheat” and send a message back in time with a measurement?

[Maximum7]

TL;DR Summary

Trying to understand the future of quantum measurements and delayed choice quantum erasers

I was watching John Michael Godier and he mentioned that since quantum measurements can change the measurement in the past (known as a delayed choice quantum eraser); that you potentially could send a message back in time. You would however have to hope the someone does the same measurement in the past at the opportune time. He doesn’t say how you could send a message since you CAN’T do that BUT humans are ingenious and creative. We oftentimes outsmart the universe at its own game. If we could figure out how to put a code in a quantum measurement that only a scientist could decode and extract; could we trick the universe and send a message back in time (assuming that someone is lucky enough to have someone see it?)

I may be way off but this is what I THINK he said in the last video.

 

[PeterDonis]

I was watching John Michael Godier

Please provide a specific reference.

I may be way off but this is what I THINK he said in the last video.

We have no way of knowing unless you provide a specific link to the video.

Also, I strongly suspect that the video is a pop science source, not an actual lecture based on textbooks or peer-reviewed papers. In which case it would not be a valid reference for PF discussion.

 

[PeterDonis]

quantum measurements can change the measurement in the past (known as a delayed choice quantum eraser); that you

No, they can't. This is sometimes claimed in pop science sources (which is why I suspect the video you watched is pop science), but it's not a correct description of what a delayed choice quantum eraser does.

potentially could send a message back in time

No, you can't use a delayed choice quantum eraser to do that.

 

[Maximum7]

No, they can't. This is sometimes claimed in pop science sources (which is why I suspect the video you watched is pop science), but it's not a correct description of what a delayed choice quantum eraser does.


No, you can't use a delayed choice quantum eraser to do that.

Alright. I usually trust John but he’s wrong. Ok

 

[PeterDonis]

I usually trust John but he’s wrong.

We don't know that he's wrong; it's possible that you are misinterpreting what he said in the video. As I said, we have no way of knowing unless you provide a link to the video.

 

[Maximum7]

 

[PeterDonis]

@Maximum7, thanks for providing the link. It is definitely a pop science video and not a reliable source if you want to understand the actual science.

since quantum measurements can change the measurement in the past (known as a delayed choice quantum eraser); that you potentially could send a message back in time

It's hard to be sure since the statements in the video are so vague, but it does appear that he is making these claims--which, as I have already posted, are wrong.

I usually trust John

If this video is typical, your trust is misplaced if you are trying to understand the actual science. This video is full of the kinds of misstatements that we end up having to help people unlearn here at PF.

 

[PeroK]

Alright. I usually trust John but he’s wrong. Ok

It's still popular science, but this video explains why the claim of retrocausaility is wrong.