Unstable particles cannot decay when observed?

[RandomBoy]

I read that an unstable particle cannot decay if one only observes it. How is this possible?

https://en.m.wikipedia.org/wiki/Quantum_Zeno_effect

[mathematic]

5 minutes ago, RandomBoy said:

I read that an unstable particle cannot decay if one only observes it. How is this possible?

https://en.m.wikipedia.org/wiki/Quantum_Zeno_effect

Sounds like pure speculation.

[Sensei]

"Observation" does not literally mean "human eye watching event"..

 

There is one known radioactive decay mode which can be stopped/delayed.

If radioactive isotope decays exclusively through electron capture, and it's all the time kept in state in which electrons are ejected from atom (ionized), nucleus can't capture electron, and decay can't happen.

 

[Strange]

6 hours ago, RandomBoy said:

I read that an unstable particle cannot decay if one only observes it. How is this possible?

https://en.m.wikipedia.org/wiki/Quantum_Zeno_effect

It only applies to certain types of changes, not all particle decay. And it is a result of making measurements. The measurements affect the state of the particle or system.

Here is an analogy. Imagine someone walking along a road. Every so often an "observer" wants to know how far they have got so he asks the person to stop while gets a tape measure (or laser range under) out and measures how far they are from the starting point. If the observer does this once an hour or every ten minutes, then it won't have any effect on the walker's progress. But if it is done every second, then the walker will never get anywhere.

(Maybe someone who understands the effect better will say if that is accurate or not!)

[StringJunky]

2 hours ago, Strange said:

It only applies to certain types of changes, not all particle decay. And it is a result of making measurements. The measurements affect the state of the particle or system.

Here is an analogy. Imagine someone walking along a road. Every so often an "observer" wants to know how far they have got so he asks the person to stop while gets a tape measure (or laser range under) out and measures how far they are from the starting point. If the observer does this once an hour or every ten minutes, then it won't have any effect on the walker's progress. But if it is done every second, then the walker will never get anywhere.

(Maybe someone who understands the effect better will say if that is accurate or not!)

Could it be the act of observation adds energy to the observed which prevents it decaying?

[Strange]

3 minutes ago, StringJunky said:

Could it be the act of observation adds energy to the observed which prevents it decaying?

My (limited) understanding is not that it adds energy but that the act of measurement "resets" it. So it never progresses.

[StringJunky]

5 minutes ago, Strange said:

My (limited) understanding is not that it adds energy but that the act of measurement "resets" it. So it never progresses.

Right. OK.

[swansont]

1 hour ago, Strange said:

My (limited) understanding is not that it adds energy but that the act of measurement "resets" it. So it never progresses.

Yes. There's a small chance that the decay will happen between the measurements, but it's like the system has just started out in that configuration each time you measure it. It has no "memory" of how long it had been in that state before the measurement.

[RandomBoy]

So can we change things by looking at them?

[Dubbelosix]

On 28/09/2017 at 0:41 AM, RandomBoy said:

I read that an unstable particle cannot decay if one only observes it. How is this possible?

https://en.m.wikipedia.org/wiki/Quantum_Zeno_effect

It's absolutely real, and is called the zeno effect. There is also an anti-zeno effect which can arise if you don't measure the atom accordingly, and has to be measured before it reaches its half-life. Basically this periodic act of observing keeps shuffling the energy states into stable ones. 

Ultimately, you are halting the evolution of the systems wave function.

Edited September 29, 2017 by Dubbelosix

[Strange]

22 minutes ago, RandomBoy said:

So can we change things by looking at them?

No. But you can if you interact with them. For example, if making a measurement means shining a light on it, or something.

"Observation" in this context doesn't just mean looking.