All Questions
221
questions
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
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
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
40
votes
12
answers
13k
views
Does information have mass?
Does information itself have any detectable mass? If so, how is the mass of information measured if at all possible? Mathematically, is it possible for information itself to have mass? What would be ...
- 659
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
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
21
votes
4
answers
4k
views
Why do we need high energy to explore small dimensions?
I am taking a quantum physics class, and for the life of me, I can not remember why we would need a vast amount of energy to understand the microscopic universe.
21
votes
1
answer
4k
views
How much of Earth's mass is created by the energy of the core?
I've read that higher energy means higher mass, and in atomic systems, the kinetic energy and potential energy actually contributes more mass than the actual particles themselves (or so I've read). So,...
- 365
19
votes
2
answers
11k
views
What did Tesla mean by "there is no energy in matter"?
I was reading "THE ETERNAL SOURCE OF ENERGY OF THE UNIVERSE, ORIGIN AND INTENSITY OF COSMIC RAYS" by Nikola Tesla, and he states:
"There is no energy in matter except that absorbed from the medium....
- 449
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 ...
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
14
votes
5
answers
8k
views
Does potential energy of an object increases its relativistic mass?
I know that in relativistic condition the increase in kinetic energy of an object increases its relativistic mass as $$m=\frac{m_0}{(1-v^2/c^2)^{1/2}},$$ and mass is another form of energy.
So my ...
- 141
13
votes
6
answers
21k
views
What happens to the mass of a burned object?
If I were to burn a pile of wood weighing a hundred kilograms and I would have a big sack hanging over the burning pile. In this sack I would catch all the smoke that came from the burning pile, if ...
- 179
13
votes
11
answers
4k
views
True or False: energy is conserved in all collisions [closed]
Using introductory physics, how would you answer this question? (I have a disagreement with my instructor and I’m curious to hear your input)
One of us says true because the question doesn’t specify “...
- 139
13
votes
2
answers
2k
views
In special relativity is mass just a measure of all other energy than kinetic?
The energy momentum equation in special relativity is:
$$E^2=(pc)^2+(mc^2)^2.$$
and it holds for a moving but not accelerating object.
One special case is the massless photon:
$$E=pc.$$
And another ...
- 357