Recent content by PeroK

Another question is whether punctuation exists?

In GR, light moves on null worldlines, which means that the speed of light, as measured locally, is a universal invariant. Measured globally, speed is coordinate dependent. There is no unambiguous way to define speed across a region of curved spacetime.

Nothing in physics exists or everything in physics exists, depending on your definition of existence. In neither case does the theory or the experimental data change; hence, the physics does not change. It makes no difference whether we decide that energy exists or not. This is, therefore, a...

Yes, see the above notes from Lancaster University, section VII.5.

A particle is defined by its (mathematical) description. There is no alternative underlying reality. This is the lesson of QM. A car is not a good analogy for an electron. There is no underlying position that is more fundamental than what QM describes. In the early days of QM, there were...

Within QM, infinitely precise position states are not physically viable. Instead, a particle is described by a wave-packet, which implies a range of possible position measurements and a range of possible momenta. The Heisenberg Uncertainty Principle (HUP) applies to these wave-packets. You...

Load nuclear bomb on rocket. Launch rocket. Land on Mars. Detonate nuclear bomb. What could possibly go wrong?

I explicitly stated that the boxes be considered rigid atomic components. Under that assumption Newton's laws apply, with a single external force and an equal and opposite third-law pair between the boxes. That is a called a simplifying assumption. We can then test this assumption and Newton's...

First, consider box 1 and box 2 as rigid atomic components. If you apply a force ##F## to box 1, then that force must accelerate box 1 and 2. The force box 1 exerts on box 2 is less than ##F## and depends on the ratio of the masses. It is in fact: $$F_2 = \frac{m_2}{m_1+m_2}F$$The same...

That still counts as homework. All the more reason to post a full problem statement.

If this is homework it should be in the homework section. In any case, you need to post a full problem statement.

Planet? What planet? At that scale gravity will dominate any realistic electrostatic force. You would be better taking a fixed central charge of ##Q## and a charge ##q## of mass ##m##. Where the charges have opposite signs.

It's also important to specify the field of scalars, which is part of the definition of a vector space. The Real numbers are a subset of the Complex numbers and a real vector space, but not a complex subspace.

It's life Jim, but not as we know it!

The surface of a sphere is generally the simplest example of curvature. You don't need an embedding space. You can treat the sphere as a manifold in its own right, without embedding it in a higher dimension. The tangent space would be a plane at each point. And, there's no unique way to say when...