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  1. Dadface

    I Experimental confirmation of the Born rule

    If we assume that a particle can be detected at a particular location, how can we do the detecting?
  2. Dadface

    B Zeno effect question

    [this thread was forked from; the "equation above" can be found there] If the quantum Zeno effect is real and if it can be quantified shouldn't the maths be specific to the event being observed? For example...
  3. Dadface

    I There are no particles, only fields!

    It seems to be widely accepted on this forum that fields, not particles, are fundamental. In other words particles are made of fields. I have seen particles described in various ways such as being excitations of fields or eigenstates with known energy. This creates a problem for high school...
  4. Dadface

    Funding research

    [This thread was forked from] I think that some scientists in particular theoreticians, need to occasionally use some popularising skills in order to justify their work to those who hold the purse strings. Quite...
  5. Dadface

    The pros and cons of pop science

    When anyone on PF gets involved in a debate and uses pop science to back up their argument their opinion is usually immediately rejected on the grounds that pop science as a source is unreliable and lacking in the necessary detail. Only peer reviewed works are accepted and in general that's...
  6. Dadface

    Essay Writing Services

    A few minutes ago I was searching for details of a particular experiment and google came up with a list of companies offering essay writing services. I had a quick glance at one of them and they seemed to offer a whole range of services going from writing up high school projects to writing up...
  7. Dadface

    I Spontaneous parametric down conversion photons

    When I look at certain experiments involving entangled photons generated by spdc, for example quantum eraser experiments, it seems to me that each observed pair of entangled photons is propagated in a horizontal plane. However, aren't the entangled photons generated randomly in all planes...
  8. Dadface

    I Energy Changes Between PE and KE

    Imagine an event where, for example, two equal mass but oppositely charged objects approached each other from rest under the influence of the electrical force of attraction between them. In terms of energy we can say that the loss of electrical potential energy is equal to the gain of kinetic...
  9. Dadface

    I QM Assumptions Regarding Entanglement Properties

    In a nutshell I think that in local realistic theories it is assumed that: Each entangled object has definite properties at all times, even when not observed. I know the assumption is proved to be incorrect but is that an assumption actually made in such theories? But what assumptions about...
  10. Dadface

    I Sorry but it's wave particle duality again... When people come to this forum enquiring about the concept of wave particle duality the usual advice seems to be based on the idea that the concept is outdated and has historical interest only. The problem is that...
  11. Dadface

    The famous scientist and the famous rock musician

    Can't help seeing some similarities. If Newton were alive today I wonder if he would be a fan of Led Zeppelin. Perhaps he would occasionally fill in for Robert Plant.
  12. Dadface

    I What Came First the Magnet or the Field?

    Below I paraphrase David Tong from: David Tong -- What is Quantum Field Theory? You can find this by googling. 1. "According to our best laws of physics the fundamental building blocks of nature are fields." 2." Every particle in the universe ... is a tiny ripple of the underlying field"...
  13. Dadface

    I Renormalisation and the Landau pole

    In the B level thread:......"how to change electron and proton charge" was claimed that "the closer you get to an electron the bigger the charge". This struck me as odd because I though that electron charge was a fundamental constant and so I asked for clarification. This was given...
  14. Dadface

    Will Constructor Theory achieve its' claimed Potential?

    Firstly an apology...I don't know what level my question should be aimed at and what forum it should be set in and I think that level A and Quantum Physics are as good as guesses as any. Moderator please moderate if necessary. It's about constructor theory, something that I wouldn't normally...
  15. Dadface

    I Virial theorem as applied to hydrogen atom

    In the virial theorem the numerical value of the average potential energy within a system is exactly twice that of the average kinetic energy. I know the theorem is proved mathematically but to me it seems a coincidence that one value is exactly twice the other value. I find that interesting. I...
  16. Dadface

    I Why does "wave particle duality" not exist anymore?

    I think I've asked this question here before but I'm still not clear about the answers. To reiterate, some experts on this forum seem to be of the opinion that wave particle duality doesn't exist anymore and this has been expressed in different threads and in different ways with certain...
  17. Dadface

    I Would studying MWI be a waste of time?

    There seems to be a lot of discussion on the Many Worlds Interpretation here at the present time and it's something that I personally can't get into very deeply. The reason I can't be bothered too much about it is because I can't help feeling that the whole concept is nonsensical. I base this...
  18. Dadface

    Can arXiv papers be considered as reliable sources of information?

    Is it correct to assume that, in general, authors who have papers accepted by arXiv eventually try to get their work published in a journal? If so what should we make of arXiv papers which apparently do not get accepted by any journals? Should we take those papers as seriously as we would take a...
  19. Dadface

    I Changing field patterns

    I hope someone here can help me and jog my memory. Some time back I was reading something on this forum which struck me as being a bit strange but nevertheless interesting. I made a mental note of coming back to the topic and taking a proper look at it But the trouble is I've forgotten the...
  20. Dadface

    Thinking outside the box

    We're often told that it's helpful to think outside the box. But what is the box we need to think outside of? And what happens when we think inside the box? I've been searching everywhere for the box but I can't find it. Has anybody got it? o0)
  21. Dadface

    I Noether theorems, the Lagrangian and energy

    I have read in different places that an up to date definition of energy refers to the Lagrangian and Noether. But isn't the Lagrangian too limited because it refers to an ideal situation involving translational KE and to PE only? I would have thought that a good definition of energy would be...
  22. Dadface

    I Unpolarised Light.

    If I'm correct,in classical physics we can define completely unpolarised light as light where the vibrations of the electric vector occur equally in all directions simultaneously. But can such a definition apply to single photons and if so are the different vibrations assumed to be in...
  23. Dadface

    I Is quantum weirdness really weird?

    The so called weirdness of quantum theory seems to be widely publicised particularly in the non specialist popular literature. However many of the experts in this forum seem to be of the opinion that there are rational explanations to much of the weirdness. What I would like to know is the...
  24. Dadface

    I Bell Test Experiments

    As I understand it most, if not all, experiments carried out to test Bells theorem test the local hidden variables assumption that photons have definite polarisations. What I would like to know is whether experiments on properties other than polarisation have been carried out. If not are there...
  25. Dadface

    I Polarisation entanglement

    If we don't know the polarisation state of a photon before detection is it reasonable to assume that it's in a superposition of all possible states? Thank you if anyone can clarify.
  26. Dadface

    I Birgit Dopfer interference experiment

    Hello. I'm interested in the experimental details of the above and have found what I believe to be the original published write up of the experiment. The document is in German and I have managed to get a reasonable understanding of the details mainly from the diagrams and graphs. Translation is...
  27. Dadface

    Entangled states before observation.

    I think this is just a quickie. I'm interested in what is assumed about entangled photons/particles before they are observed. Is it correct to assume that the photons/particles exist in all possible states simultaneously? Thank you.
  28. Dadface

    Delayed choice quantum eraser by Kim et al.

    Hello I have been looking at the results published by Kim et Al and am a little bit baffled by one of the graphs shown in fig 4. which shows the single detector counting rate of Do. The rate is very approximately constant across the whole range and averages about 280000 counts per second. Very...
  29. Dadface

    B Bell spaceship paradox - qualitatively

    [Mentor's note: This thread is forked from for discussion of the basic principles behind the spaceship paradox] Suppose the string was replaced by some structure which linked the ships together to make a longer...
  30. Dadface

    The Equivalence of Mass and Energy

    Hello I've been trying to get confirmation, or otherwise, that the total mass of an atom can be considered to be equal to the sum of the masses of the individual atomic particles it contains plus the mass equivelent of the internal energy, (PE+KE), of the particles. I have also been trying to...