@danielunderwood more general audience..doing some high level research...

↑ synchronicity/ [fluid dynamics] sign from the heavens :) :P

Morning. For the project I'm making, I'll need 1500V (150k V\m) to move TiO2 particles across a 1 cm container. How do I figure out how much current I'll need (and therefore power)?

The current will be tiny

electronics.stackexchange.com/questions/452839/… :P

If you think about the amount of charge that is flowing it's just a few charged TiO2 particles. The current will be so small as to be hardly measurable.

I'm just following this guy's instructions.

You won't need anything like 1mA. It would be more like 1 microamp.

That doesn't help me in any way to design the circuit :P

I mean, I now know the power, so?

I can select a proper battery?

Why would I go through the trouble of using a crystal, when in the end, I'll convert the AC to DC? (I mean, is it a DC alternating pulse, or just straight line DC)

Sorry to say this here and now but I really need help with my question. Would any one help?

@Korra yes, what's the question?

this physics.stackexchange.com/questions/496532/…

Ah, I can't help, sorry. It's too long since I did QM with delta potentials and I don't remember how it's done.

Thanks for the reply though!!

@deadpool hi

@JohnRennie hi

can you please clarify my last query?

This?

yes please, not sure if its a valid question though..

The block universe isn't really a theory in the usual physical sense.

In physics a theory is some mathematical model that we use to make predictions that can be tested against experiment.

Then if the experiments don't match the prediciton we know the thoery is wrong.

But the block universe idea isn't of this form. It's hard to see how you could ever do an experiment to prove or disprove it. It's more like a philosophical position.

I would guess most physicists don't have a strong view on the block universe and/or they dismiss it as irrelevant speculation.

if time is just a co-ordinate we should be able to traverse it in any direction right? is it the ever increasing entropy the factor which prohibits it?

You have to consider how we perceive time passing. We presumably do this using our brain, and the brain is basically a machine so like all machines it runs in the direction of increasing entropy.

So the point is that the brain runs in the direction of forward time so by definition it can only ever perceive time going forward.

It's not that time actually flows forwards, just that we think it flows forwards because that's how our brains operate.

i will think this over in the coming few days :) thank you

There are some hints of time being directed though

Like how qft has a prefered time direction

@Slereah Why does QFT have a preferred time direction?

Do you mean that CP violation implies time reversal symmetry is violated?

@JohnRennie momentum operator has spectrum in the forward light cone

It's why you don't get advanced waves

9V battery connected to a crystal so we get alternating 9V. We then connect to a transformer to get very high voltage and very low current. I then convert that to a steady straight line DC voltage (using a rectifier, I guess). Will that work?

someone just posted the same answer 14 times within 9 minutes (a wall of text copied and pasted): physics.stackexchange.com/users/207730/ten1o?tab=answers

as far as I understand from my meta question, this is totally fine.

@thermomagneticcondensedboson I've flagged one of the answers for the mods to look at if they want to take any action. I guess the OP isn't actually violating any rules.

I feel like there should be some type of rule against that... It doesn't seem fair that someone is able to post so many answers that I would consider bad (just on the basis of not really addressing the specifics of the questions); but because of the sheer volume of low quality answers in such a short period, I likely can't downvote all the bad ones without triggering a reversal script

@JMac Yeah... This is weird

Okay... now that I look at it, I' surprised that posting 14 answers in 10 minutes with identical text doesn't trigger some sort of automatic spam response.

Just downvote and move on. I wouldn't downvote all 14 answers or the serial downvote detector will kick in. I've downvoted three of them.

@JMac We do get flags when identical answers are posted, so we're aware of it (independent of the additional flags). But it never hurts to flag things for us to look at!

If you guys can do us some favors -- if you look at the duplicated answers and think they don't actually answer the question, then flag it as "not an answer" if it's warranted.

Posting the same answer to multiple questions is definitely frowned upon on SO. I'm sure there are SO meta posts about it. But of course Physic.SE is somewhat different to SO.

@PM2Ring It's frowned upon system-wide:

The attitude on SO is that if the same answer is valid on multiple questiins, then those questions are probably dupes, and the usual dupe closing / flagging applies.

Or the question is so poorly written that multiple answers apply

@tpg2114 Thanks. I figured it would be. But I try to be aware of the differences between the various sites, and to not treat all SE sites as clones of SO.

@enumaris power efficient everything.. basically. If you have a power constrained space, you can things many orders of magnitude cheaper than classical digital. The only thing that I have that I would say is a "product" level is a key word detector. It is programmable, recognizes voices regardless of accent and can do it in 50nW. The digital solution takes Watts. (don't know how much, it uses a computing cluster)

How is the most common case of spam ever not automatically cleared or at least put on hold for moderator approval?

@VictorS the system detects possible spam and alerts reviewers to it.

It appears in the review queues

So all those 14 copypasta spam posts would require all of the review flags to remove

Or votes

@VictorS Note that on SE sites the term "spam" refers to commercial spam: posts wih links that attempt to make money, either directly or via ad revenue. Posting commercial spam carries heavy penalties: a loss of 100 rep points, and IP bans for repeat offenders.

That makes sense

@VictorS they've all been deleted now and indeed the account has been suspended.

When dupe answers get posted like that, it's not unusual that the poster isn't actually the author. They've pinched it from another answer, or another site. And since they give no attribution, that's plagiarism, which is a big no-no.

I'd say that is a bit of a grey area with the non-academic setting and all that

It becomes more of a matter of good manners to provide your original reference but then a lot of forums posting involves anonymized bits to the point it becomes impossible or even absurd to provide a reference pointing to some other post

It's not just good manners. If you aren't the creator of content, you must give attribution, and you must have the right to re-publish it, since you're giving Stack Exchange the right to publish it under the Creative Commons licence. See the Subscriber Content section here: stackoverflow.com/legal/terms-of-service#licensing and creativecommons.org/licenses/by-sa/3.0 which is linked at the bottom of every page.

But sure, if you're posting stuff that's common knowledge it'd be tedious to give attributions. OTOH, if (for example) you post something from Wikipedia you must make that clear in your post, and give the link.

This just popped up in my Facebook feed. It's an old joke but strangely appropriate :-)

@JohnRennie Sadhguru

@NovaliumCompany :-)

He has a pretty awesome discussion with David Eagleman (pretty cool guy)

@bdegnan and that's on an analog neuromorphic chip right? Thanks for the insight! :D

@bdegnan also is there a paper I can cite for this keyword detector?

Well, I think that Sadhguru is still a crank. He's a claim of making scientific statements ain't scientific actually. He has more to religion than science.

← lol @ JRs citation of an authority :P

@PM that is still a matter of good manners because if you copypasta off wikipedia or worse, off a paper, people will find out and most likely dogpile you as such is the way of the forum

Would a chromebook be good for an engineering student?

I'm interested in those 360 degree flipping chrome books with touchscreens

They're alright for taking notes and stuff

Not for anything fancy beyond web browsing though

Coding?

heard VSCode works well on them

I ask this question because I am not aware what software are needed for an engineering student (assume a Computer Science student)

Yeah simple coding should be fine

@VictorS "Nothing fancy", because of OS limitations or hardware limitations?

A bit of both

Shame, no good chromebooks available in my country.

They are either awful ones, or super expensive

bam bam

@JohnRennie Although some people do enjoy engaging in pointless arguments with "fools". I see it all of the time here ;)

Yes, you are right.

@Hilbert Yes

@AaronStevens Thank you!