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Tell me Physics facts!

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Reply 40
Original post by safesploit
Because it was from my general reading :biggrin:


Ok. It's just that there was, like, an entire episode dedicated to this. He lost a lot of sleep, told an anecdote about Einstein, became a waiter and then had a eureka moment when he dropped some plates. Not sure where to find it online, but the episode was called "The Einstein Approximation" iirc.

Physics fact #294761:
Changing electric fields induce changing magnetic fields

but...

changing magnetic fields can induce changing electric fields. So you can create an electromagnetic wave that propagates by continually inducing a new field just a little further on.
You can't feel the attractive force of gravity.
Even more interesting is that gravity is not a force (at least classically).

Original post by Stonebridge
You can't feel the attractive force of gravity.
Original post by hestermae
basically time travels slower the faster you travel, if you travel at speed u relative to an observer the the time you measure = t/sqrt(1 - u^2/c^2) I think where t is the time the observer measures I think
so like time is dilated and the closer to the speed of light you travel the more time is dilated
like its not really you're travelling forward in time but like your clock just ticks slower than someone elses clock who you're moving relative to
also like weird stuff happens when you have acceleration and like I think space time bends and stuff but we dont do general relativity till 3rd year so I dont know that much about that


Interesting, thank you
Original post by Stonebridge
You can't feel the attractive force of gravity.


Surely if you stuck me between two supermassive objects, I'd be able to feel their pull?? Suppose they're even SUPER supermassive and I'm fixed in place, I'd definitely feel them tearing my limbs off. :tongue:
Reply 45
Original post by Hype en Ecosse
Surely if you stuck me between two supermassive objects, I'd be able to feel their pull?? Suppose they're even SUPER supermassive and I'm fixed in place, I'd definitely feel them tearing my limbs off. :tongue:


It's all relative.

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Original post by WishingChaff
Not really true. It is questions like this that have led to huge breakthroughs in the standard model of particle physics (specifically the study of the higgs field). If you wish to read more about it, the wikipedia article on tachyonic fields is rather informative.


We'll put it this way - my tutor at Oxford works at CERN and is pretty much an expert on the standard model and is one of the world's leading particle physicists. His view on tachyonic fields is 'bull****'. They are generally considered a curiosity by experimentalists at the moment.
Original post by RoyalBlue7
<a rel="nofollow" href="javascript:void(0)"><img src="http://www.thestudentroom.co.uk/latexrender/pictures/55/554ed9cf768b3b97c220a766c367a3b0.png" width="74" height="17" style="border: 0px; margin: 0px; padding: 0px;" alt=" E = mc^2 " title=" E = mc^2 " onclick="newWindow=window.open('http://www.thestudentroom.co.uk/latexrender/latexcode.php?code=+E+%3D+mc%5E2+','latexCode','toolbar=no,location=no,scrollbars=yes,resizable=yes,status=no,width=460,height=320,left=200,top=100');" /></a>


Only when relative speed between frames is less that 0.1c does it approxise to the above. Otherwise would be this.



:albertein:


@OP

This is a pretty good youtube channel with lots of physics videos aimed at ordinary folk.

https://www.youtube.com/user/sixtysymbols


Here's one

[video="youtube;Cxqjyl74iu4"]https://www.youtube.com/watch?v=Cxqjyl74iu4&amp;list=PLcUY9v udNKBNwkTA_1VWz8JeqO8HU15qo[/video]
(edited 9 years ago)
Original post by Hype en Ecosse
Surely if you stuck me between two supermassive objects, I'd be able to feel their pull?? Suppose they're even SUPER supermassive and I'm fixed in place, I'd definitely feel them tearing my limbs off. :tongue:


Hm. Surely in that case the forces from the two objects on every atom in your body would balance and you'd feel nothing?
It's not quite as good as Chemistry.
Original post by Stonebridge
Hm. Surely in that case the forces from the two objects on every atom in your body would balance and you'd feel nothing?


Yeah, the more I try to think of examples, the more I realise you're right! It doesn't matter what I do in that scenario, the only thing I'll feel is the acceleration due to gravity, rather than the force of weight itself.
I'm not really sure what to say to this. Your supervisor is very much entitled to his opinion however, I don't believe he would dismiss it in this way, and this is in fact your vanity coming across. Anyway, as an active researcher in theoretical physics I can confidently say that this is not a question that should be instantly dismissed. It has, as I said before, led to huge breakthroughs into many branches of physics, including (experimental) particle physics and the theory of superconductors. Rather than making spurious statements like this, I suggest you speak to your supervisor as you may actually learn something from him.

Original post by natninja
We'll put it this way - my tutor at Oxford works at CERN and is pretty much an expert on the standard model and is one of the world's leading particle physicists. His view on tachyonic fields is 'bull****'. They are generally considered a curiosity by experimentalists at the moment.
Reply 52
Original post by Stonebridge
Hm. Surely in that case the forces from the two objects on every atom in your body would balance and you'd feel nothing?


Surely if they're sufficiently dense then the part of you closest to Mass A is attracted more to A than to B? So you'd get spread out between them because you'd have a continually increasing net force going out from the centre of your body.

(Just to be clear, you still don't 'feel' gravity, unless you're being spaghettified by a black hole. And in that case you're feeling a difference in gravitational field strength across your own body. And you're probably dead.)
(edited 9 years ago)
Reply 53
Original post by Stonebridge
Hm. Surely in that case the forces from the two objects on every atom in your body would balance and you'd feel nothing?


In theory yes.... However you have to remember that gravity has a range

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Reply 54
Original post by lerjj
Surely if they're sufficiently dense then the part of you closest to Mass A is attracted more to A than to B? So you'd get spread out between them because you'd have a continually increasing net force going out from the centre of your body.

(Just to be clear, you still don't 'feel' gravity, unless you're being spaghettified by a black hole. And in that case you're feeling a difference in gravitational field strength across your own body. And you're probably dead.)


Better wording than mine, but it's what I tried to say.

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Original post by lerjj
Surely if they're sufficiently dense then the part of you closest to Mass A is attracted more to A than to B? So you'd get spread out between them because you'd have a continually increasing net force going out from the centre of your body.

(Just to be clear, you still don't 'feel' gravity, unless you're being spaghettified by a black hole. And in that case you're feeling a difference in gravitational field strength across your own body. And you're probably dead.)



Original post by Andy98
In theory yes.... However you have to remember that gravity has a range

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Certainly, if you are in a non uniform field such that there is a difference between your head and feet you would get stretched. My original post was referring to the standard F = GmM/r2 force on an object in a field, which you don't feel. It was meant to stimulate discussion. Seems like it did, too.
The most powerful force in the universe is in your hand.

You are 99.9% empty space.

Other facts:

The Catholic church cannot have mass without the Higgs boson.

42
Original post by jamesgates1

42


What question does this answer though? :confused:

:colone:

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Reply 58
Original post by Hype en Ecosse
What question does this answer though? :confused:

:colone:

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42 is the ultimate answer to life, the universe and everything.

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Original post by Andy98
42 is the ultimate answer to life, the universe and everything.

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Someone needs to brush up on their Hitchhiker's! :tongue:

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