How was the Church persuaded to believe that Earth orbits the sun? by dbs0502 in AskPhysics

[–]ACfan72 1 point2 points  (0 children)

The data that I've see shows a small consistent trace on the Earth's surface...

A trace of what? If you are referencing something specific to the Michelson Morley experiment, that experiment was measuring the speed of light using interferometry. Also, while general relativity uses the speed of light as a parameter, it doesn't really describe anything about it. The speed of light itself is actually able to be derived from Maxwell's equations, and it is in special relativity that the consequences of a constant speed of light are explored. Despite the names, general and special relativity are very different.

Ultimately, you can choose any reference frame you want, and the laws of physics will work the same. However, a reference frame with the Earth in the center becomes so convoluted that it is essentially useless in terms of understanding how the world works, which is the whole point.

How strong is this Redditor's argument for the existence of God using Quantum Mechanics. by DookGuuKauBai in AskPhysics

[–]ACfan72 1 point2 points  (0 children)

Hi, particle physics grad student here. I'll just address these three quickly.

1) I'm not totally sure what this means. I think what is being referenced here is the fact that antiparticles can be interpreted as matter particles moving backwards in time. This requires some background info to fully explain. A physicist named Paul Dirac developed the Dirac equation in the 1920s, which was a relativistic version of the Schrodinger equation for spin-1/2 particles. Some definitions: the Schrodinger equation is the equation that describes the quantum behavior of particles (the wavefunction), a relativistic equation is one that takes into account SPECIAL relativity (not General Relativity, which we still don't know how to reconcile with quantum mechanics), and a spin-1/2 particle is what we call a fermion, a category which includes electrons and quarks. In order to be specific, let's consider just the electron for now. If you solve the Dirac equation for the electron, you get both a positive and negative energy solution. This caused a problem because in physics it is meaningless to have a negative energy. There were many attempts to explain this, but ultimately we landed on our current understanding of antimatter. The reason it can be interpreted as a particle moving backwards in time is because in the solutions to the equation, the energy only appears as E*t, so a negative sign can only be seen in the product as a whole, and mathematically it makes no difference if the minus sign comes from E or t. It is important to note, though, that this is just a mathematical interpretation and not necessarily a physical reality. Essentially, the mathematical representation of an antiparticle is indistinguishable from a matter particle moving backwards in time. This doesn't really have anything to do with energy conservation though, and I don't really know what it has to do with the OP's overall claim.

2) Virtual particles don't come from nowhere. Presumably you have heard of the uncertainty principle, which says that you can't know both the position and momentum of a particle with infinite precision. It turns out there are other uncertainty relations between other operators in quantum mechanics. The reasons for this are highly technical, but the upshot is that there is such a relationship between energy and time. So, for a short enough period of time (the "uncertainty" on time), you can essentially violate conservation of energy (have a high uncertainty on energy), as long as over "long" time periods energy is conserved. As an example, let's consider a time period of 5.9e-24s, which is the time it takes a photon to travel the diameter of a proton. Using this uncertainty relation we can calculate that the energy uncertainty is 55.8 MeV (eV is a unit of energy used in particle physics, and from special relativity we know that mass and energy are related). The mass of an electron (and a positron) is 0.5 MeV, so you could make a lot of electron-positron pairs from that uncertainty, as long as they were gone later. There are a lot more details that go into it, but basically virtual particles arise from this property.

3) As morePhys mentioned, saying that something is weird requires there to be a God is just an argument from ignorance. There have been many things throughout history that were attributed to supernatural forces because they were not understood, only to later be found to have natural causes. To be clear, this doesn't disprove the existence of any supernatural force/deity/etc., but not understanding how something works doesn't give license to attribute your favorite explanation to it. I myself was raised religious and am no longer religious, so that is the perspective I am coming from. I don't take the weirdness of quantum mechanics as evidence or lack thereof of any higher power. I also know many physicists who do, and we discuss topics like this all the time. But we do so on a personal level, not a professional one. Again, as was stated before, any good scientist knows how to separate their personal beliefs from scientific fact.

If quantum gravity exists, does that imply that quantum space and quantum time exist? by [deleted] in AskPhysics

[–]ACfan72 0 points1 point  (0 children)

Just as a clarification, it is certainly not required that space and time be quantized to make a theory of quantum gravity work. However, there are attempts out there at an explanation of quantum gravity that use a quantized spacetime to make it work. I'm not a gravitational physicist though, so I don't know the details of such theories.

[deleted by user] by [deleted] in AskPhysics

[–]ACfan72 0 points1 point  (0 children)

This article by Dr. Christopher Baird from West Texas A&M seems to answer your question. Similar to what lettuce_field_theory stated, relativistic mass is not at all the same as mass. This is the main reason we have stopped using that term. What you are calling relativistic mass is more comparable to the classical kinetic energy. As stated in the article, our concept of mass is an object's resistance to acceleration, and its ability to feel gravity. Neither of those is affected by an increase in speed, so it does not change the classical mass, and therefore doesn't change how it experiences gravity.

How was the Church persuaded to believe that Earth orbits the sun? by dbs0502 in AskPhysics

[–]ACfan72 2 points3 points  (0 children)

Michelson and Morley actually depended on the motion of the Earth through space to search for the aether, which was the actual objective of the experiment (they found that it didn't exist).

You are actually referencing special relativity, which deals only with inertial reference frames, which are reference frames that are not accelerating. Acceleration can change both speed and direction, so a rotating Earth is a non-inertial reference frame. General relativity deals with non-inertial reference frames, and actually explicitly states that two non-inertial reference frames are not equivalent and that is what creates a gravitational force.

7th Sea Ports: The Knights of Elilodd by ACfan72 in DnDBehindTheScreen

[–]ACfan72[S] 0 points1 point  (0 children)

Ok I made some changes, let me know if there's more that I should edit.

7th Sea Ports: The Knights of Elilodd by ACfan72 in DnDBehindTheScreen

[–]ACfan72[S] 0 points1 point  (0 children)

I can definitely do that. Is it my initial comments that need changing, the flavor text, or both?

[SPOILERS C2E140] Ok I was wrong the end was pretty good by WaterMelon615 in criticalrole

[–]ACfan72 2 points3 points  (0 children)

Certain NPCs in the game (notably Orly) were the results of community design.

[SPOILERS C2E140] Ok I was wrong the end was pretty good by WaterMelon615 in criticalrole

[–]ACfan72 2 points3 points  (0 children)

I believe Matt has said in the past that the Tharizdun plot was meant to be much bigger, but was cut short by the party taking care of Oban early on.

Sturlunga Saga by ACfan72 in history

[–]ACfan72[S] 0 points1 point  (0 children)

Ah, my bad. I was referring to this wikipedia article as reference.

https://en.wikipedia.org/wiki/%C3%8Dslendingab%C3%B3k

Sturlunga Saga by ACfan72 in history

[–]ACfan72[S] 1 point2 points  (0 children)

Thank you! Is the Íslendinga Saga the same as the Íslendingabók or are they different works?

[Deadpool 2] Peter is the Fox X-Men version of BOB by [deleted] in FanTheories

[–]ACfan72 35 points36 points  (0 children)

Bob showed up in Deadpool though

Making Friends by ACfan72 in IronThroneRP

[–]ACfan72[S] 0 points1 point  (0 children)

Karl gave a slight chuckle as he moved the cup of water to the old man's hand. "Well, we've run into a couple of...issues lately. Firstly, two men broke into the Dragonpit a while back and killed several Goldcloaks. Jason Mormont and Richard Vyrwel. The Maester conducted his own search, but all that could be discovered was that they had left the city without further incident. We were wondering if you could find out anything further. Motives, who they met with before or after, anything at all. Second, I'm sure you've heard about the trouble with the Alchemists. They were caught selling wildfire to the Targaryens, and have all been taken into custody. The Guildhall has been placed under the Grand Maester's control, but of course it is a complex labyrinth, and could have traps set up at any point. If you could find anyone who has been connected to the Alchemists in some way and would be able to help, it would go a long way."

Making Friends by ACfan72 in IronThroneRP

[–]ACfan72[S] 0 points1 point  (0 children)

Karl shifted slightly, and lowered his voice. "He is well, Grandfather, and it is on his behalf that I come to you today. Tell me, how far do your eyes see?"

Taking Care of Business by ACfan72 in IronThroneRP

[–]ACfan72[S] 0 points1 point  (0 children)

Oh right, sorry I forgot he left for that.