All Questions
53
questions
16
votes
9
answers
5k
views
How can gravity affect light?
I understand that a black hole bends the fabric of space time to a point that no object can escape.
I understand that light travels in a straight line along spacetime unless distorted by gravity. If ...
66
votes
6
answers
9k
views
What keeps mass from turning into energy?
I understand the energy and mass can change back and forth according to Einstein. It is fluid; it can go from one to the other. So, what keeps mass from just turning into energy? Is there some force ...
- 945
30
votes
3
answers
19k
views
Does $E = mc^2$ apply to photons?
Photons are massless, but if $m = 0$ and $E=mc^2$, then $E = 0c^2 = 0$. This would say that photons have no energy, which is not true.
However, given the formula $E = ℎf$, a photon does have energy ...
user1313
12
votes
3
answers
6k
views
Explain how (or if) a box full of photons would weigh more due to massless photons
I understand that mass-energy equivalence is often misinterpreted as saying that mass can be converted into energy and vice versa. The reality is that energy is always manifested as mass in some form,...
- 21.1k
47
votes
6
answers
8k
views
Do photons gain mass when they travel through glass?
Please correct me if I'm wrong, but I believe that photons slow down when travelling through glass. Does this mean they gain mass? Otherwise, what happens to extra kinetic energy?
I understand now ...
- 1,248
1
vote
3
answers
2k
views
Is light affected by gravity? Why? [duplicate]
I would like to know if light is affected by gravity, also, I would like to know what is the correct definition of gravity:
"A force that attracts bodies with mass" or "a force that attracts bodies ...
- 41
55
votes
7
answers
54k
views
Is a hard drive heavier when it is full?
Browsing Quora, I saw the following question with contradicting answers.
For the highest voted answer:
The bits are represented by certain orientations of magnetic fields
which shouldn't have ...
- 2,784
24
votes
7
answers
10k
views
What is the symmetry which is responsible for conservation of mass?
According to Noether's theorem, all conservation laws originate from invariance of a system to shifts in a certain space. For example conservation of energy stems from invariance to time translation.
...
- 2,080
2
votes
2
answers
545
views
Travel at the speed of light
Is it me who have a poor understanding, or does all matter have to become 'pure energy' in order to achieve speed-of-light speed?
If so, does that mean that no material can achieve the speed of light ...
- 175
3
votes
2
answers
1k
views
Can the mass of a hydrogen atom be calculated in a gauge-invariant way?
Please excuse the lengthy question. It involves an interesting controversy which has arisen in discussions on this site:
Energy/mass of Quantum Vacuum
Relative potential energy vs Absolute potential ...
- 51.7k
15
votes
2
answers
3k
views
Has it been experimentally proven that energy causes gravity?
I know that under general relativity energy and mass are equivalent under $E=mc^2$. But has it been experimentally proven that energy alone causes gravity, for example, does a nuclear reaction ...
- 4,783
11
votes
3
answers
4k
views
Where does all the mass created from energy go?
So mass can be created from energy when small protons speed up, 430 times bigger to be exact. I don't know if this is a stupid question, but I'm in middle school so cut me some slack. Where does all ...
- 109
10
votes
4
answers
3k
views
Can massless particles travel slower than the speed of light in vacuum?
We know an object with positive mass cannot be accelerated to the speed of light because this would require an infinite amount of energy. My question is:
Is there anything in the universe that can ...
2
votes
4
answers
4k
views
Conversion of mass and energy
First of all I am not a scientist and all these doubts are coming from my curiosity.
When Googling about Einstein's $E = mc^2$. I understand that mass and energy are convertible.
What it exactly ...
- 137
2
votes
5
answers
3k
views
Derivation of $E=pc$ for a massless particle?
In classical mechanics, massless particles don't exist because for $m=0$, $p=0$.
The relativistic relation between energy, mass and spatial momentum is: $E^2= (pc)^2 + (mc^2)^2$ . So it is said that ...
- 121