Causality Question: Is It Violated in This Scenario?

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In summary, the physicist was asking if the A lamp would light first if the B lamp was already turned on. Some people thought that it would, because the causality concept says that information travels between the lamps at the speed of light. But the physicist explained that there is a difference between "at the same time" and "almost at the same time" and that in this case, the B lamp would light just a little earlier than the A lamp.
  • #1
fluidistic
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I didn't know where to ask this question, so excuse me if I posted it in the wrong place.
Recently I've been listening to a video in which a physicist asked a question to the public (in a high school I believe). I've had my own idea about the answer of the question, but the physicist (Étienne Klein) claimed an unexpected answer.
I'm talking about the causality in our universe.

The problem was stated more or less like that :
Say we have 2 incandescent lamps connected with a wire. I call a lamp the A lamp and the other the B one.
If someone turn on the A lamp then the B lamp will light just after (the information that the A lamp has been turned on travels by the wire between the 2 lamps).
Now suppose the disposition of the 2 lamps is like that : B-------------A. And that I am there : (.)-----B-------A. (I am situated over the point).
The question was "If the A lamp is turned on, which lamp will you see that light first?". Few people answered it was the A lamp that would be seen first as lighted, because they were just told the causality concept. But for my part I don't understand why wouldn't I see the 2 lamps be turned on on the same time. The information that travels in the wire is almost the speed of light, so I would see the 2 lamps light in the same time... or am I really wrong? If yes, why? I know that the causality cannot be violated but in such an example, the only way for me to understand that I'd see the A lamp light first is that the information that the A lamp doesn't travel at the speed of light in the wire.
In that case if the B lamp light when it sees that the A lamp light, then I'd see the 2 lamps light at the same time, right? Is the causality violated in such case?
Hope you could understoood my question.
 
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  • #2
Your answer is pretty much correct. But the fact that light traveling through air is a bit faster than signal travelinmg through wire does make a difference, so you would see light from lamp A just a little earlier than from B. For most physysists, there is a big difference between "at the same time" and "almost at the same time."
 
  • #3
Thank you LURCH. Now I understand it better at least. Maybe the causality concept could be explained as "nothing can travel faster than light" and then all the conclusions would follow. But as I never studied it yet, I better not to make such a guess!
 

Related to Causality Question: Is It Violated in This Scenario?

What is causality?

Causality is the relationship between cause and effect. It is the principle that an event or action (the cause) produces a certain outcome (the effect).

How is causality violated?

Causality is typically violated when an event or action does not produce the expected outcome or when an outcome occurs without a clear cause. This can happen due to errors in measurement, confounding variables, or other factors that affect the relationship between cause and effect.

Can causality be proven?

Causality cannot be proven with absolute certainty, but it can be supported by strong evidence and logical reasoning. Scientists use different methods, such as experiments and statistical analysis, to determine if a causal relationship exists between variables.

What is the difference between correlation and causation?

Correlation is a statistical relationship between two variables, while causation is a cause-and-effect relationship between two variables. Just because two variables are correlated does not necessarily mean that one causes the other, as there may be other factors at play.

How can causality be established in a scientific study?

To establish causality in a scientific study, researchers must carefully design their experiments or studies to minimize the influence of confounding variables and other sources of bias. They may also use control groups and randomization to strengthen their findings.

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