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/sci/ - Science & Math

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>> No.5832850 [View]

>>5832413
>Radiation ≠ light
It's not exclusively light. Radiation can be pretty much anything.

>>5832473
No.

>>5832479
Basically. The energy of the BH's gravitational field produces particle-antiparticle pairs near the event horizon (they are actually produced everywhere, but the horizon is where it's interesting), and when one of them escapes it carries off energy with it.

>>5832798
>Light is not actually massless; it's just inconceivably small.
It's theoretically zero according to all modern physics, and all experiments are in agreement (to an absurdly high degree of accuracy) with this.

>> No.5823689 [View]

>>5823688
Sure it is. Unless you're somebody who doesn't have an internet-capable phone.

>> No.5823032 [View]

You should really get help.

>> No.5818889 [View]

Hint: fundamental theorem of calculus.

>> No.5818886 [View]

>>5818878
Forgot the link:
http://physics.stackexchange.com/questions/55278/distance-traveled-in-a-simple-two-body-problem/55284

>> No.5818878 [View]

It's a second order differential equation that can't be naively solved by integrating twice. It's also a two-body problem, so unless one of the masses is much larger than the other you can't simply neglect the motion of the other body. I made a semi-detailed post on stack exchange where the asker wanted to know how to calculate the time it would take for two masses to come together under gravity. You can use the same approach to find r(t).

>> No.5816250 [View]

>>5816244
How do you define and measure intelligence? If you can't, on what basis do you think your claim holds any merit?

>> No.5806239 [DELETED]  [View]

>>5806220
Well the first thing you have to do is parametrize the surface, then express the vector field in terms of your parameters. After that it's just straight-forward calculation.

If you know that the vector field is always normal to the surface, you can use the divergence theorem to turn it into a volume integral. This could greatly simplify the problem.

>> No.5804682 [View]

>>5804622
For some reason this shit seems to be rampant on /sci/. Whenever I see a thread about time, I inevitably see a post about how time doesn't "really" exist, and how it's "actually" [ill-defined nonsense].

>> No.5804652 [View]

>Catch is, to join they require that you're part of an institution or an independent researcher with valid papers, credentials or abstracts...

How, exactly, is that a catch? That seems like a perfectly viable bullshit detector to me. Granted not all bullshit will be caught in this net, but it seems better than letting crackpots with nonsense "theories" post without some sort of filter.

>> No.5804639 [View]

Sure. It's called "energy."

This is a trivial result of special relativity - we deal with four-vectors (vectors with four component, three spacial and one temporal). Four-momentum is defined as:

<div class="math"> p_\mu =(E/c,p_x ,p_y ,p_z)</div>

where:

<span class="math">E=\gamma mc^2[/spoiler]

<span class="math">p_x=\gamma mv_x[/spoiler]
etc. for the y and z components, and:

<div class="math">\gamma =\frac{1}{\sqrt{1-( v_x^{~2} + v_y^{~2} + v_z^{~2})/c^2}}</div>
Given the numerous relationships between time/energy and space/momentum, this shouldn't be too surprising. For example, conservation of energy is a consequence of time translation symmetry, while conservation of momentum is a consequence of spacial translation symmetry.

>> No.5799091 [View]

Those are parametrized with respect to x already...

>> No.5794130 [View]

I'd imagine it's so that they keep up with each other.

>> No.5788832 [View]

Probably the first one (assuming intelligence and attractiveness don't overlap). Because attractiveness, by definition, is the quality that attracts mates.

>> No.5788392 [View]

I'm not gay so I may have a non-functioning gaydar (unless someone is extremely flamboyant/limp-wristed/talks with a lisp I can't really tell) but I don't think a significant portion of the physics majors at my schools are gay.

>> No.5787498 [View]

>>5787492
Peskin and Schroeder I see?

>> No.5787338 [View]

What do you mean? Is there implied redundant notation in every representation of a number?

>> No.5787159 [View]

>1. Physical 1,000,000,000-dimensional space: it can be?
It can be what?

>2. How can we imagine?
You can't. You can't even imagine 4 spacial dimensions (fuck off Jacob Barnett), so there's literally zero way for you to imagine such a space.
3.What kinds of matter and the interactions can there be?
The same kinds. But there is way more freedom than in 3D space, so the likelihood of an interaction occurring is a lot smaller.

>> No.5783875 [View]

>>5783862
>superluminal time travel

I'm not familiar with this, so perhaps you could elaborate on exactly what you mean. I'm familiar with tachyonic antitelephones, where you can send signals to the past. But a superluminal object experiences imaginary time, which doesn't really make any physical sense.

>> No.5783859 [View]

>>5783844
>Does it have an imaginary length?

As far as naively calculating things goes, yes. Physically this is meaningless, because tachyons don't exist.

>> No.5783840 [View]

I'm guessing you're calculating the interval? First off, it's important to note that there are two commonly used conventions for the interval: the (-+++) and the (+---) conventions. In the first (using units where c=1 for simplicity), the interval is defined as:

<div class="math">ds^2=-dt^2+dx^2+dy^2+dz^2</div>
In the second:

<div class="math">ds^2=dt^2-dx^2-dy^2-dz^2</div>
Depending on your convention, a negative interval could mean two completely different things. In the first, it means that the worldline is timelike (i.e. events along the worldline can be causally connected). In the second, it means that the worldline is spacelike (events cannot and are not causally connected).

An example of a timelike worldline would be a particle's path through spacetime. A spacelike interval may correspond to an object's length, for example.

In the first convention, the interval actually corresponds to proper length. In the second it corresponds to proper time.

>> No.5779507 [View]

Have a look at Taylor's book. It has an excellent introduction to Lagrangian/Hamiltonian mechanics.

>> No.5778597 [View]

Also, your basic premise is patently false. You suppose that the event horizon is a genuine singularity, rather than an artifact of the particular coordinate you're using. Since you can get rid of the singularity by simply changing your coordinates, this is obviously an incorrect hypothesis.

I fear you're taking coordinates too seriously.

>> No.5778584 [View]

I don't really know what you were trying to show or how you can really claim that you showed anything. Your letter was a mish-mash of disorganized ideas, and you jump to random conclusions with no explanation.

I assume the reason he hasn't responded is because he doesn't want to waste his time correcting your confused nonsense.

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