# All Questions

136 views

### Classical Mechanics - Allowed systems

I've edited my question to clear any possible confusing parts: This an exercise from the book "The Theoretical minimum", I'm paraphrasing. In classical mechanics, dynamical laws must be reversible ...
76 views

### Muons Internal Clocks and Time Dilation? [closed]

I don't get how time dilation affects the half-life of muons? Time is just a tool that is used by humans how does that affect the internal clocks of elementary particles?
387 views

### Is the thickness of a sample related to the intensity of x-ray diffraction?

I understand that in general if we're adding more planes of atoms (increasing thickness of sample) then the intensity would increase because we have more constructive interference. But isn't there a ...
632 views

### Extremal black hole with no angular momentum and no electric charge

A black hole will have a temperature that is a function of the mass, the angular momentum and the electric charge. For a fixed mass, Angular momentum and electric charge are bounded by the extremality ...
99 views

### Michelson interferogram white light pattern symmetry

Why is the white light of the interferogram produced by using Michelson Interferometer necessarily symmetric? This is really hard to think.
127 views

40 views

### Molecular formula of a compund [closed]

I have no idea on how to get information out of this one. A compound contains only hydrogen and nitrogen. Nitrogen makes up for 87.4% of the mass. A sample of this have a density of 0.977 g/L at ...
18k views

### Is the universe finite or infinite?

I thought the universe was finite, but then I read this: How can something finite become infinite? And they seem to assume it is infinite. So which is it?
8k views

### How can something happen when time does not exist?

I saw this documentary hosted by Stephen Hawkins. And if I didn't get it wrong, it says that there was no time before the big bang, time was created there. So how can anything happen when there is ...
173 views

### Could there be more universes?

In the documentary: "Curiosity - Did God Create the Universe (on YouTube)", theoretical physicist and cosmologist Stephen Hawking states that time did not exist before the big bang. The first ...
3k views

### What does it mean to be stationary?

I'm looking for a simple answer. What do we regard a stationary. Do we mean an object that is not moving noticeable from the viewers perspective because then a parked car would be considered ...
169 views

### What's the typical material used as a low-k ILD in semiconductors?

Semiconductor companies (namely IBM, Intel, TSMC and etc.) may use different low-k materials as inter-layer dielectric (ILD) in their fabrication process. I'm wondering what is the most typical one. ...