Does observed light travel faster or slower than unobserved?

[scifimath]

I realize that unobserved light it going to be difficult to measure, but could the double slit experiment be set up to give us an average air time for the particles? I find it hard to believe that a particle acting as a wave would travel at exactly the same speed as an observed one.

 

[Nugatory]

You have been reading popularizations based on misconceptions from almost a century ago, before the modern theory of quantum mechanics was developed. The idea that things act as waves when they aren't observed and as particles when they are observed was abandoned long ago and is no part of the modern formalism of quantum mechanics.

 

[scifimath]

So it's not worth testing out ..just-in-case?

 

[Nugatory]

So it's not worth testing out ..just-in-case?

There's no way of saying whether the experiment is worth doing until until you have described it in detail: How are you setting things up, what are you going to measure when, what results does quantum mechanics predict for these measurements, how does your experiment differ from experiments that have already been done so that it's asking a new question?
Of course you cannot specify the last two until you know enough of the existing theory to calculate (quantitatively, not qualitatively!) what it says should happen and are familiar with the experiments that have already been done.

You started this thread at the I level, so you may be comfortable with something like Susskind's https://www.amazon.com/dp/0465062903/?tag=pfamazon01-20. That won't help so much with the details of the experiments that have already been done, but it will start you in on what quantum mechanics really says.