Reality Definition and 413 Threads

Greg Bernhardt submitted a new PF Insights post Orbital Mechanics in Unity Game Engine for Augmented Reality Continue reading the Original PF Insights Post.

I mean there is this division between virtual (in static situations) and real photons as the quanta of the EM field, but aren't all photons essentially "virtual" in the sense that they are purely made up by us in order to explain why we see discrete impacts of specific energy for a given EM...

Hi, like the title says, how do we actually calculate when a cantilever beam fails in reality? We’ve been taught that these are absolutely fixed to the ground. However, in reality these would probably be bolted onto the ground, so how do we calculate the force trying to lift the fixed beam on...

As you might know, the simulated reality idea says that our universe is a simulation by some higher order beings. Some scientists and philosophers taken it quite seriously while others dismissed it. Is there anyway to prove whether our universe is simulated or not for sure? And will our...

Sorry if this is the wrong thread but subject wise it seemed the most appropriate. Are there any books available that take a deep dive into the heady mathematics you guys use here BUT that take the time to tie things back to reality? And I'm talking about something for interested laymen like...

This might be a stupid question so please bear with me. I am having a debate with a friend of mine over the Internet. It is about science. His argument is that although science works (that is the technology part), science cannot actually tell anything about "reality". He sites for example...

Hello, I would like to hear some comments on this: Recently a paper has been published(Sánchez-Kuntz, N. & Nahmad-Achar, E. Found Phys (2018) 48: 27. https://doi.org/10.1007/s10701-017-0126-z) claiming tha QM has a local realist interpretaion. In this paper it is asserted that: "The wave nature...

I'm reading "Division Algebras and Quantum Theory" by John Baez https://arxiv.org/abs/1101.5690 In the last paragraph of section 5 (Applications) he says the following "SU(2) is not the only compact Lie group with the property that all its irreducible continuous unitary representations on...

For each action there is an equal and opposite reaction (third principle), and no one would ever think to say that the action is "real" and the reaction is "apparent". Also the centripetal force is an "action" to which (as it happens for all the actions) it corresponds *always* an equal and...

So I was doing some calculations last night on railguns for fun, and I got some very surprising results which seams like they must be wrong. The calculations are simple and I must have overlooked something. So we all know that F = B * I * L when all are orthogonal, a capacitor discharge is I =...

Hi everyone ! I would like to know the real meaning of scalar product. So, I know scalar product is defined as : ||a||.||b||.cos(a;b) = k But what k is ? (Sorry for my english, I am french). Regards :)

Hello Everybody, I hope that I've picked the right sub-forum for my question. The problem is as follows: I understand perfectly well the proof by contradiction of the irrationality of the square root of 2, where we prove that if we assume that it is rational, then the integers of which the...

What type of lens/prism would be needed to allow a image sensor to see 180 degrees, so the sensor could see a hemisphere. It doesn't matter if the input is distorted. I thought that a glass pyramid with a square base might work.

Before I tried VR headset. I thought it was just looking at screen closeup. but no.. it's more than that. I mean.. it's like you are really immersed in the surrounding and there is 3D effect I haven't foreseen. Most of those who haven't tried it wouldn't appreciate the experience. To those who...

Hi, my Name is Markus and I'm from Germany, I have more a lingustic & IT background with basics in physics from school times (some years ago, I have to say). I have a couple of more holistic questions, hope that is ok, please let me know, Have a great day!

Do you regard relativistic effects to be physically real or just apparent (kind of like optical illusion caused by distorted information one is receiving)? To prevent endless entanglement in "define physically real" arguments imagine this: two spaceships moving inertially relative to each...

In 2015, the Australian National University conducted an experiment that showed that reality does not exist when not measured. But how is it that things exists on the macroscopic scale even when they are not measured? http://www.anu.edu.au/news/all-news/experiment-confirms-quantum-theory-weirdness

While the title may seem to overblow it, showing that negative mass exists may be just that big. After all, as I understand, the primary obstacle to the reality of the Alcubierre Drive or Krasnikov Tubes is the negative energy density requirements. This of course violates certain energy...

Are there any events in reality, or is everything a continuous process? If events exist, do they have precise beginnings and ends? When a photon hits an electron, is that an event? Does that "event" have a beginning and an end? Could the big bang be considered the only event? Can there be any...

In quantum physics, one can change a system just by observing it, such as wave function collapse and quantum Zeno effect. I don't quite get how observation affects them, unless we are interacting with them when observing them.

My story has a Superman analogue as the protagonist. His talents include the basic “flying brick” goodies, but no other powers. Early in the story, soon after he was “transformed”, he’s flying in for a landing in his current, drug-ridden, residential neighborhood at night. He happens to look...

Which course do you guys think would be more interesting/helpful for a physics major? They are both 100 level, Intro consists of two lectures and a seminar a week, and Practical Logic consists of a three hour lecture once a week.

I'm reading the paper of the EPR paradox and I'm confused in the meaning of this: "The elements of the physical reality cannot be determined by a priori philosophical considerations, but must be found by an appeal to results of experiments and measurements......when the operators corresponding...

Does this mean that we will one day have an answer to the old age question on the ontology of the wave function: Towards optimal experimental tests on the reality of the quantum state http://iopscience.iop.org/article/10.1088/1367-2630/aa54ab

Hello, here there are 2 things (one about hologramic universe and the other about a quantum physics test similar to the slit lamp. The first one is about the Bohm and Pibram as well as one about Alain Aspect 1982 study: articles about their theories...

Hi, i want visualize a 3D configurator like this in reality. I have print the configurator in 3D but the result was not very good. How I can visualize the 3D configurator in reality in best. Thanks.

I found this optical illusion today on the internet. This posting is accompanied by an explanation of how it works, that invokes lateral inhibition among neurons in the visual system. There is another version of this available on the internet where they show two versions. one version has red...

I was just reading a paper <predatory publisher reference deleted> There is an argument (originally by Spekkens), in Section 2.1, that is supposed to be against psi-ontic interpretations. As I understand it, it's that if someone hands you a particle in state x+ or y+ you cannot tell the...

While the mathematics and the experimental results of de Broglie's equation are clear, what is the best understood explanation as to what is happening in underlying reality of why wavelength varies (inversely) with momentum for all energy and matter ?

Consider a cat in a box in a room. The box also contains some radioactive isotope. A geiger counter detects if the atom decays, and if it does, it sends a signal to some sort of computer, which causes a hammer to fall and smash open a bottle of poisonous gas. So, if the atom decays, the cat is...

QM declares reality to be inherently indeterminate. Another hypothesis is that it is in fact determinate, but due to measurement uncertainty appears to be indeterminate. Why did Bohr, Heisenberg & Co adopt the first hypothesis and reject the equally valid second, when the two are experimentally...

Just started reading this book as an introduction to physics with a background of electrical engineering. It is absolutely fascinating and being new to the forum I'd appreciate it if anyone had any suggestions for further general learning. Thank you all for inspiring me to learn more physics...

Hi, I've been reading Roger Penrose's Road to Reality during my free time, and I am trying to do all the proofs I possibly can, although I am quickly reaching my limit. Would somebody help me prove this? h(x)=0 if x ≤ 0 h(x) = e-1/x if x > 0 Thank you in advance :)

People are free to post here their ideas and watched scenes involving SF actions, whether they can be realistic or not.

I just want to share my paper I recently wrote. I am trying to submit for publication: [Reference to unpublished paper deleted]

If reality requires an observer, and life on Earth is only 3.8 billion years old- yet the universe is 13.8 billion years old, who was the observer for the first 10 billion years?

I'm reading The Logic of Modern Physics by P.W. Bridgman (1927). He states an operational definition of reality: something is a "good construct" if it has a one to one correspondence with a physical situation defined by observations, but it isn't "real" until it has multiple...

Currently I am working on a manga/comic of mine which imvolves science, especially stuff related to quantum mechanics. The theme of my manga is based on the 'collapsing of realities'...i.e, realities from different timescales would collapse at one place and try to exist at once, which would...

Humans created that tool, that language, that consists of axioms and their implications. Mathematics do a good job of communicating the behavior of physical phenomena. In some instances, pure mathematical areas have been found to describe some aspect of reality, only years after having been...

I have thought about virtual reality headsets and other futuristic devices for a month now, but now I it has peaked my interest enough to ask about it on the forum. My idea for a safe virtual reality headset would be a device that is able to use a method similar to that of dreams. I thought of...

Hi, I have a silly question, Could one, in theory make a accurate model of the life of our universe that one could look at from within. Let's say I put on my VR/AR goggles, 'there' Iam elevated from the earth, then I remain static, and the time begins to rewind. At some point I maybe hear...

The gear ratio is the ratio of angular displacement, angular velocity, angular acceleration, torque etc of the input with respect to output. However, I would like to know that which of these variables will be scaled exactly to the gear ratio in reality, as there might be some friction in the...

In the Wilsonian viewpoint, quantum electrodynamics is an effective theory, where the low energy predictions are obtained by coarse graining eg. some form of lattice QED where the lattice is taken very finely. In the Copenhagen interpretation, we are agnostic as to whether the wave function is...

Hi Do Quantum Mechanics negates the reality of matter and proves un-reality of matter ?

Interesting new work on the link between quantum state vectors are physical states: Can different quantum state vectors correspond to the same physical state? An experimental test Daniel Nigg et al 2016 New J. Phys. 18 013007 Abstract A century after the development of quantum theory, the...

Hi, I’m new to the forum and I would like to ask some questions. I’m not a physicist –for some reason that I’ll always regret I chose Business Studies- and my knowledge of physics is limited to high school, physics books and documentaries; which I must have watched them all by now. Anyway, for...

(I apologize beforehand if I'm asking such an 'amateur' question , I admit that I'm not a physics student / physicist nor scientist / science student ,.. but , as just a 'normal ordinary' person, at least I am very interested in these things ,. and how I deeply wish Humanity / Mankind can 'leap...

While learning about SR, I encountered the famous Minkowski spacetime. At first I thought it was just a useful mathematical trick, with no particular physical meaning. But reading more about it, it seems that this notion of spacetime is often (always?) regarded as the actual physical reality...

As I understand it, the standard spacetime model is a 4-dimensional geometric object, and that my personal history is just a particular curve in the model. Reality as I experience it though is that I move through time, and thus I have the concept of the present in which "now" corresponds to the...

The other day, in conversation, I attributed the dictum, "If you can't measure it, it isn't real!" to Lord Kelvin. However, when I chanced to look it up in Wiki, I could find no confirmation of this attribution. Was I mistaken? Did Lord Kelvin ever say anything to this effect? If not, is...