並べ替え:
新着
注目トップ論争中

Physics 内の feuer01 によるリンク To what should I pay special attention in highschool, in order to have less problems in physics later?

[–]iorgfeflkd 0ポイント1ポイント  (0子コメント)

I dunno there's a bunch of good comments.

askscience 内の lostintransactions によるリンク How can we see photons from distant Galaxies?

[–]iorgfeflkd 9ポイント10ポイント  (0子コメント)

Everything you've described is correct. It's not an "infinite" resource of photons, but for a star like the sun it's roughly 1045 per second.

Galaxies emit a lot of photons, so many of them arrive at the Earth even though we make up a tiny fraction of the total solid angle. When we start looking at far enough sources, or in parts of the spectrum that are dimmer, we start to see photons arriving one at a time instead of as a continuum.

askscience 内の WildBeast26 によるリンク Do the laws of attraction still apply in space?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

Electrostatic attraction and repulsion is the same in space as on Earth. Gravity is not relevant.

math 内の iamiamwhoami によるリンク Does the dirac delta function have a residue?

[–]iorgfeflkd 2ポイント3ポイント  (0子コメント)

Does cosh have a Fourier transform if it doesn't satisfy the Dirichlet conditions?

askscience 内の PM_ME_FUN によるリンク Does light have mass?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

No because they're never at rest.

Physics 内の qwertyolol によるリンク Can physics explain the beginning of everything? Can it explain where the laws of physics came from?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

You mean beyond big bang cosmology?

Physics can't yet explain where physics comes from, we're still at the point of just trying to understand the universe as it is.

askscience 内の undergroundmoose によるリンク Would a strong magnetic field have any effect on an electrical circuit?

[–]iorgfeflkd 5ポイント6ポイント  (0子コメント)

Yes. Overall a magnetic field applies a force to a current-carrying wire, which is the principle behind electric motors. On a smaller level, a magnetic field applied to a circuit makes electrons deflect, and causes an imbalance in the electron density which leads to a voltage perpendicular to the direction of the current, called a Hall voltage.

Physics 内の AutoModerator によるリンク Physics Questions Thread - Week 22, 2015

[–]iorgfeflkd 0ポイント1ポイント  (0子コメント)

Thanks for the info. This is one of my "physics shower thoughts."

There is a first-order quantum correction to Newtonian gravity (here: http://arxiv.org/pdf/gr-qc/9310024.pdf) which is roughly 10-93 for a 1 AU orbit; it's proportional to planck length over radius squared.

AnimalsBeingJerks 内の CarmineFields によるリンク Y'know sometimes I just get sick of fish...

[–]iorgfeflkd 0ポイント1ポイント  (0子コメント)

100 bucks on the cat.

AnimalsBeingJerks 内の 1Voice1Life によるリンク You shall not pass!

[–]iorgfeflkd 2ポイント3ポイント  (0子コメント)

/r/cowbeingcow

Physics 内の AutoModerator によるリンク Physics Questions Thread - Week 22, 2015

[–]iorgfeflkd 0ポイント1ポイント  (0子コメント)

I know that but that wasn't my question!

TheSimpsons 内の goodeggforyou によるリンク Always protect your head

[–]iorgfeflkd 2ポイント3ポイント  (0子コメント)

http://3.bp.blogspot.com/-bFD_rRuQs6I/VIdDhwcfddI/AAAAAAAALe8/uHwvSnEJEHY/s1600/simpsons-safety-posters-can-really-come-in-handy-while-at-work-9.jpg

Physics 内の [deleted] によるリンク Intergalactic Expedition

[–]iorgfeflkd -1ポイント0ポイント  (0子コメント)

/r/homeworkhelp

math 内の JH1010 によるリンク What is the link between sin and sinh?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

In addition to what everyone else said, the Taylor series of sinh is the same as the series for sin except with all terms positive.

Physics 内の kwantize によるリンク String Theory: is research funding stagnant, growing or shrinking? Should a new grad student pursue or avoid ST?

[–]iorgfeflkd 0ポイント1ポイント  (0子コメント)

There are applications of holography in condensed matter physics (look up a review by Subir Sachdev), which might be as interesting for you.

edit: here's the review http://arxiv.org/pdf/1002.2947.pdf

Physics 内の tyler4693 によるリンク Mathematician John Nash spoke of tweaking Einstein’s theory of relativity days before death

[–]iorgfeflkd 21ポイント22ポイント  (0子コメント)

I feel like this is a grasping-at-straws article somebody wrote based on that cellphone picture someone posted in /r/math. It's pretty devoid of content.

askscience 内の PM_ME_FUN によるリンク Does light have mass?

[–]iorgfeflkd 24ポイント25ポイント  (0子コメント)

Gravitational fields are changes in the geometry of spacetime, and light follows that geometry.

askscience 内の PM_ME_FUN によるリンク Does light have mass?

[–]iorgfeflkd 21ポイント22ポイント  (0子コメント)

As far as we know, they do not. If they do, it must be below about 10-54 kg (1023 times smaller than the electron's mass) to be consistent with what we have observed.

Physics 内の spsheridan によるリンク LHC's first collection of physics data at 13 TeV will start tomorrow.

[–]iorgfeflkd 5ポイント6ポイント  (0子コメント)

They're going to get so many inverse femtobarns.

askscience 内の reanimatoruk によるリンク Is there a physical model for gravitation that matches the verified predictions of GR but which operates within flat Minkowski spacetime?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

Probably the closest thing to what you want is the Post-Newtonian expansion, which expresses things in terms of their first-order deviation from Newtonian gravity.

However, any such model is just an approximation to actual general relativity.

askscience 内の CptSnowcone によるリンク What are some examples of objects that have significantly measurable levels of Snap, Crackle, and Pop?

[–]iorgfeflkd 2ポイント3ポイント  (0子コメント)

Something simple like a pendulum or a mass on a spring has nonzero values of all these. The question isn't measuring them, as you said, it's finding use for them.

A lot of robotic devices that interface with people, e.g. modern prosthetics, utilize these higher derivates so match the inherent shakiness of human motion. Minimizing jerk is a common design goal. Here's an old but free paper on the topic: http://www.jneurosci.org/content/5/7/1688.short

Here's a thesis that goes down to the pop level: http://escholarship.org/uc/item/8s79b77v

Physics 内の feuer01 によるリンク To what should I pay special attention in highschool, in order to have less problems in physics later?

[–]iorgfeflkd 4ポイント5ポイント  (0子コメント)

A pitfall students fall into is focusing on values rather than general relationships between quantities. So if a 5 kilogram weight hits a 3 kilogram weight at 5 meters per second and you are told to write the velocity after the collision, the naive thing to do is start writing (5 kg x 5 m/s...) when the better thing to do would be start writing (m1 v1 = m2...) to find a general relationship between quantities.

Physics 内の AutoModerator によるリンク Physics Questions Thread - Week 22, 2015

[–]iorgfeflkd 4ポイント5ポイント  (0子コメント)

When I was learning about quantum mechanics and general relativity, I thought there might be some significance to solving the Schroedinger equation in the Schwartzschild effective potential. Something about how quantum particles would behave in a strong gravitational field, like electrons around a Planck-mass source, without having know the full quantum gravity. I was probably wrong, but is there any significance to that? Has anyone tried calculating it?

Physics 内の Ghost_K によるリンク Tachyon experiment?

[–]iorgfeflkd 4ポイント5ポイント  (0子コメント)

There was a kerfuffle in 2011 because a neutrino experiment claimed to measure them going faster than light, but that was a bad signal due to a loose cable.

Your teacher might be referring to this: http://news.bbc.co.uk/2/hi/science/nature/841690.stm

Physics 内の barraymian によるリンク Can a theoretical physicist become an experimental physicist?

[–]iorgfeflkd 1ポイント2ポイント  (0子コメント)

Yes. It happens.

My friend did his master's in theory and his PhD in experimental, for example.

続きを見る 次 ›