Ask a physicist anything. (8)

[GrowingSmaller]

Is it possible that a the Big Bang particles came to predominate in a way that mirrors biological evolution. i.e. certain particles we see today were generated through some form of differential replication...

 

[Wiccan_Child]

Is it possible that a the Big Bang particles came to predominate in a way that mirrors biological evolution. i.e. certain particles we see today were generated through some form of differential replication...

So, particles create more particles whose properties are 'inherited', albeit imperfectly? That would do it, but we'd need a major overhaul of physics and several layers of sub-quark particle structure. Nice idea, though.

 

[Zippy the Wonderslug]

Hi.

Could someone please explain, simply in baby words for me to understand, what time dilation is all about?

Say I have two stop watches.

I start them both at exactly the same time.

I take one of them on a road trip in my car and drive like crazy and fast on the highway and then return back home an hour later.

Why are these two stop watches no longer recording at the same time?

The watch I drove is a few seconds slower.

I don't understand this.... Like, at all.

This honestly wobbles my brain.

Cheers everyone!

 

[Wiccan_Child]

Hi.

Could someone please explain, simply in baby words for me to understand, what time dilation is all about?

Say I have two stop watches.

I start them both at exactly the same time.

I take one of them on a road trip in my car and drive like crazy and fast on the highway and then return back home an hour later.

Why are these two stop watches no longer recording at the same time?

The watch I drove is a few seconds faster.

I don't understand this.... Like, at all.

This honestly wobbles my brain.

Cheers everyone!

It's definitely one of the weirder effects of Relativity.

In a nutshell, time dilation is the difference in how two clocks tick when one moves relative to the other. If you and someone else hold two identical clocks, and someone drives away at near the speed of light with one clock, and you can see what their clock is doing, you would see their clock slow down relative to yours: it would tick slower. Peculiarly, if the driver looked at you, they'd see your clock ticking more slowly than theirs.

This all comes about because the speed of light is constant in all inertial frames - c is c and can't be anything but. So if you start driving at crazy speeds, space contracts and time dilates to make c stay the same - and this isn't a quirk of the mathematics, we've done experiments and found this really happens.

So what's happening? Well, the driver sees you receding into the distance, so your clock, the one that's moving, slows down. You see the driver moving, so his clock slows down. If he turned around and came back towards you, the acceleration would sort those clocks out, solving the apparent paradox of both clocks being slower than the other.

 

[Zippy the Wonderslug]

Wow.

Thanks!

My question came after viewing this YouTube video.

Slow Down Time! - YouTube

54 mph in a car is nothing near 186,000 mps.

I'm still trying to wrap my stupid brain around this concept.

I don't think that I will ever fully get this.

 

[Zippy the Wonderslug]

Oh, speaking of YouTube...

Cool Sound and Water Experiment! - YouTube

This has to be an optical illusion, yes?

I've read many of the posted comments on this but was hoping to hear from a real physicist.

Cheers.

 

[Elendur]

Oh, speaking of YouTube...

Cool Sound and Water Experiment! - YouTube

This has to be an optical illusion, yes?

I've read many of the posted comments on this but was hoping to hear from a real physicist.

Cheers.

I'm no physicist but it's simple mechanics they play the music with 24 hz (hz is per second) and cameras usually records with 24 pictures per second (24 hz).

The effect makes one drop replace the previous drop in each picture.

And the sound affects the tube in a major way, enough to make the tube send out water almost the same way every time

Cool video thanks for sharing!

 

[Resha Caner]

Do the properties of the fundamental particles extend uniformly in all directions, or do some particles have an orientation?

 

[David Jerome]

Energy equals mass times the speed of light squared...what exactly does this mean?

 

[Wiccan_Child]

Do the properties of the fundamental particles extend uniformly in all directions, or do some particles have an orientation?

Some are intrinsically orientated, like the 'spin'. Some, in the absence of anything else, are uniform, such as electric charge.

 

[Wiccan_Child]

Energy equals mass times the speed of light squared...what exactly does this mean?

E = mc[sup]2[/sup] is Einstein's famous mass-energy equivalence principle, and it comes from the more general statement: E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]c[sup]4[/sup]. That is, the energy of a particle is related to its mass and momentum. When the particle is at rest, the equation settles down to the more famous E = mc[sup]2[/sup].

So what does that mean? Well, 'm' refers to the rest mass of the particle, the mass it has when it's not moving (some physicist believe that, when a particle accelerates, its mass increases, which is one reason why it's impossible to hit lightspeed; I personally don't ascribe to that idea), c is obviously the speed of light, and E is the energy a particle has.

The implication is that mass can be transformed into energy, and that the amount of energy you get from a mass m is equal to mc[sup]2[/sup]. This is experimentally verifiable when you look at the mass deficit in decaying atoms - the mass of the unstable atom is slightly more than the mass of the decayed particle and the leftover atom, because some mass is released in the form of energy (such as the kinetic energy of the released particle).

So it tells us the energy of a particle when it's at rest, the amount of energy 'locked up' in something's mass. It comes from the more general relation between energy, momentum, and mass, E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]c[sup]4[/sup].

 

[Resha Caner]

Some are intrinsically orientated, like the 'spin'. Some, in the absence of anything else, are uniform, such as electric charge.

Interesting. So that means we could detect an orientation for, say, an electron?

I'm not sure what the "intrinsic" part means, though. Does that mean that, even though spin is oriented, nothing external can change the orientation?

 

[Wiccan_Child]

Interesting. So that means we could detect an orientation for, say, an electron?

I'm not sure what the "intrinsic" part means, though. Does that mean that, even though spin is oriented, nothing external can change the orientation?

Well, the electron is always spinning one way or the other - if it were a classical, billiard ball-type particle, it would be spinning clockwise or counter-clockwise. The orientation can be changed, but it's always simply 'pointing' one way or the other. It's a bit more complex than that, but essentially that's it.

I once worked with the magnetic moments of protons, replicating the effect that makes MRI machines work. Protons are placed in a constant magnetic field, which makes their magnetic moments all point in the same direction (like iron filings), which is the equilibrium position, if you like. You then send a radio pulse, which jostles their moments, and while they return to the equilibrium state they emit magnetic goings on that we can measure. This is the basis of MRI machines, as the magnetic field can orientate the two protons in a water molecule, and water is basically ubiquitous in the body.

Anyway, the idea is that there are physical properties which point in a direction, and this direction can be manipulated quite readily.

 

[TemperateSeaIsland]

Well, the electron is always spinning one way or the other - if it were a classical, billiard ball-type particle, it would be spinning clockwise or counter-clockwise. The orientation can be changed, but it's always simply 'pointing' one way or the other. It's a bit more complex than that, but essentially that's it.

I once worked with the magnetic moments of protons, replicating the effect that makes MRI machines work. Protons are placed in a constant magnetic field, which makes their magnetic moments all point in the same direction (like iron filings), which is the equilibrium position, if you like. You then send a radio pulse, which jostles their moments, and while they return to the equilibrium state they emit magnetic goings on that we can measure. This is the basis of MRI machines, as the magnetic field can orientate the two protons in a water molecule, and water is basically ubiquitous in the body.

Anyway, the idea is that there are physical properties which point in a direction, and this direction can be manipulated quite readily.

I assume you were doing NMR spectrometry in a chemistry class?

 

[Wiccan_Child]

I assume you were doing NMR spectrometry in a chemistry class?

It was for a project at uni, actually. Hah, I wish I did something as cool as that back at school-level stuff.

Though making your own thermometer was always fun.

 

[TemperateSeaIsland]

It was for a project at uni, actually. Hah, I wish I did something as cool as that back at school-level stuff.

Though making your own thermometer was always fun.

Well I was talking about Uni level but now that you mentioned it I think I did do some NMR based pracs in A-levels (thanks to the local uni).

(Currently sorting through about 200 H1/C13 NMR spectra from 6 years ago as my former PhD supervisor decided we might be able to squeeze another paper out)

 

[David Jerome]

E = mc[sup]2[/sup] is Einstein's famous mass-energy equivalence principle, and it comes from the more general statement: E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]c[sup]4[/sup]. That is, the energy of a particle is related to its mass and momentum. When the particle is at rest, the equation settles down to the more famous E = mc[sup]2[/sup].

So what does that mean? Well, 'm' refers to the rest mass of the particle, the mass it has when it's not moving (some physicist believe that, when a particle accelerates, its mass increases, which is one reason why it's impossible to hit lightspeed; I personally don't ascribe to that idea), c is obviously the speed of light, and E is the energy a particle has.

The implication is that mass can be transformed into energy, and that the amount of energy you get from a mass m is equal to mc[sup]2[/sup]. This is experimentally verifiable when you look at the mass deficit in decaying atoms - the mass of the unstable atom is slightly more than the mass of the decayed particle and the leftover atom, because some mass is released in the form of energy (such as the kinetic energy of the released particle).

So it tells us the energy of a particle when it's at rest, the amount of energy 'locked up' in something's mass. It comes from the more general relation between energy, momentum, and mass, E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]c[sup]4[/sup].

Okay...but where does the speed of light come into play, when a particle is at rest? If E = MC 2 refers to a particle at rest, it's obviously not moving at the speed of light...and, as you said, it's believed by some that nothing can reach the speed of light, even if it wasn't at rest...so then how does light's speed relate here in this formula?

 

[Lillen]

I don't know what to ask... so i skip this thread!

 

[Lillen]

I've heard of particles moving faster then the speed of light. I read it is some school litterature in highschool. i cant remeber the name of the particle. I thought i might inform you of this!

 

[Wiccan_Child]

Okay...but where does the speed of light come into play, when a particle is at rest? If E = MC 2 refers to a particle at rest, it's obviously not moving at the speed of light...and, as you said, it's believed by some that nothing can reach the speed of light, even if it wasn't at rest...so then how does light's speed relate here in this formula?

It's not the speed of light that's important, it's just that light happens to travel at the speed that is used in the equation. It stems from the premise of Relativity: that the speed of light is invariant. This could well apply to any other particle that travels at that speed, but we just happened to know about light.