Recent content by Cato

I do not think that true emergent properties -- as defined by behavior of matter that cannot be reduced to fundamental physical law -- exist. Yet I have been told that the Fractional Quantum Hall Effect is an example of an emergent property. What is the consensus?

Correct...I was thinking of "complete annihilation" as leaving behind only photons -- that was mistaken. Yes, Ibix, I could imagine a grazing impact -- at what? more than half the speed of light? -- producing something very different from a head on collision. Would be something to see. Thanks...

If a neutron star and an anti neutron star collided, would they 1) completely annihilate each other, 2) form a black hole, or 3) partially annihilate each other with the remaining stars being pushed away from each other by the energy created?

Thanks for that answer, phyzguy! I was hoping something along those lines could occur.

Type 1a supernovas unbind a white dwarf. Is there some theoretically possible scenario in which a neutron star could be unbound and thus turned into degenerate matter or even regular matter? For example, by a high speed glancing collision with another neutron star or by tidal disruption by a...

Those are profound questions. What is necessary in order for something to have emotions is an aspect of the question of what is necessary in order for something to be conscious – the defining feature of consciousness is the ability to have subjective experience, and emotion is one type of...

Thanks for the link to thee very nice site. Good graphics and descriptions. Intuitively, if anything in QM can be said to be intuitive, it does make sense that there would be less contrast. I don't know the math, but I wonder if using two slits of different widths would result in a pattern...

If the two slit experiment is performed with one slit half the width -- or 1% or 0.1% the width -- of the other, how is the interference pattern affected.

Yep. I'm happy. What a great site Physics Forums is. Thanks, all.

Thank you, Ibix. Just so that I am clear about what you and the others are in uniform agreement on -- Imagine a purely hypothetical nonexpanding universe empty of matter except for two earth-sized bodies orbiting each other at a distance of, say,10 billion light years. Every answer I have gotten...

OK, thanks for that.

Thanks, all, for your responses. I guess I do not understand the concept of “being bound” in a gravitational interaction. I do not see how orbiting bodies are in any way gravitationally bound – they are simply falling toward each other. In a hypothetical nonexpanding universe, even far distant...

Does the expansion of the universe affect orbits? Would the orbits of the Magellanic Clouds, for example, be different if the universe were not expanding? If orbits are affected, at what scale do we first detect the effects?

Thank you! So all the talk about the importance of "observation" is mistaken. Nice to have that that settled.

I have a similar and (maybe the same?) question as UnderstandingQT. If you fire electrons toward the two slits, and you have electron detectors at each slit that are turned off, then you will get an interference pattern. If you turn the detectors on and observe the results, you will not get an...