- #1
Erdem
[SOLVED] what is physics ?
can you make one sentence explanation (definition) for physics.
can you make one sentence explanation (definition) for physics.
Originally posted by FUNKER
Ok name something any thing and then think to urself is physics involved? Then you'll know my reasoning
Originally posted by Tom
In the last century, concept of motion has had to be revised in two different ways. First, there was the relativistic revolution that forced us to put an upper bound on speeds. Second, and nearly concurrently with the first, there was the (much more drastic) quantum revolution that forced us to abandon the concept of forces in dynamics, and to abandon kinematics nearly altogether.
Originally posted by Carla1
Hiya Tom...hope things go well your way.
How did the quantum revolution force physicists (such ironic terms) to abandon the concept of forces in dynamics, and kinematics for that ...oh god I can't help myself...matter? :P
While I'm attit...what's all this wave and geodisics business about?
Originally posted by Tom
Yes, they are going well. Busy though--my students are going crazy with finals.
I'm guessing that you are our long-missing, beloved Carla. Why the name change?
Classical dynamics as a variety of equivalent formulations. On the one hand, there is Newtonian dynamics which is in terms of forces. On the other hand, there are Lagrangian and Hamiltonian dynamics, which are in terms of energies. It turns out that quantum mechaincs is modeled on the latter, and it seems that it cannot be modeled on the former. At least, no one seems to be able to think of a way to to it (we discussed this briefly in another thread I started called "Quantizing Newton", which you can find in the Archives if you are so inclined).
So, quantum mechanics is formulated in terms of energies (modeled on Hamiltonian dynamics), and the impetus of motion for particles is not a force, but a potential energy function. The next step is quantum field theory, which abandons the potential energy function in favor of a quantized interaction. In the case of the electromagnetic interaction, it is quantized into virtual photons.
As far as kinematics goes, that is a geometric description of the motion of a particle without regard for the impetus that gave rise to the motion. It is formulated in terms of the trajectory of a particle, x(t). If we take the time derivatives, we get v(t) and a(t) for the velocity and acceleration, respectively. This allows us to simultaneously calculate the position and the momentum of the particle, p(t)=mv(t), where m is the mass. But quantum mechanics tells us that it is not possible to specify both x and p. So, kinematics is out the window. (We can, however, do "kinematics" on the expecation values of the position and momentum operators, but that is another story).
I guess you'll have to be more specific about these. Quantum Mechanics is also called "wave mechanics" because it describes matter with a wave equation, and geodesics are straight lines in curved spacetime. Massless particles always follow geodesics.
Physics is a branch of science that deals with the study of matter, energy, and their interactions. It seeks to explain the fundamental laws and principles that govern the behavior of the universe.
The main areas of study in physics include mechanics, thermodynamics, electromagnetism, optics, and quantum mechanics. These areas cover a wide range of topics such as motion, forces, energy, heat, light, electricity, and particles.
Physics is important because it helps us understand the natural world and how it works. It also leads to the development of new technologies and innovations that improve our lives. Additionally, physics plays a crucial role in other scientific disciplines, such as chemistry, biology, and astronomy.
Physics is related to everyday life in many ways. For example, our understanding of mechanics helps us drive cars and operate machines. Our knowledge of thermodynamics helps us cook food and keep our homes warm. Even our use of technology, such as smartphones and computers, is based on the principles of physics.
To study physics, you need to have a strong foundation in mathematics and critical thinking skills. You should also have a curious and analytical mind, as well as a willingness to constantly question and challenge existing theories and concepts.