The 10 Most Important Physics Effects
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A count-down of the 10 most important effects in physics that you should all know about: 10: The Doppler Effect (for sound and light) 9. The (real!) Butterfly Effect 8. The Meissner-Ochsenfeld Effect The video is from here
7. The Aharonov-Bohm Effect 6. The Tennis Racket Effect The video is from her
5. The Hall Effect (and the Quantum Hall Effect) 4. The Hawking Effect (and the closely related Unruh Effect) 3. The Photoelectric Effect Einstein, yeah! 2. The Casimir Effect 1. The Tunnel Effect You can help finance my videos by donating here:https://www.paypal.com/cgi-bin/webscr...
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today I have a countdown of the 10 most
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important effects in physics that you
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should all know about starting with 10
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the Doppler effect the Doppler effect is
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the change in frequency of a wave when
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the source moves relative to the
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receiver if the source is approaching
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the wavelength appears shorter and the
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frequency higher if the source is moving
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away the wavelength appears longer and
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the frequency lower the most common
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example of the Doppler effect is that of
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an approaching ambulance where the pitch
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of the signal is higher when it moves
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towards you and when it moves away from
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you but the Doppler effect does not only
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happen for sound waves it also happens
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to light which is why it's enormously
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important in astrophysics for light the
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frequency is the color so the color of
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an approaching object is shifted to the
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blue and that of an object moving away
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from you is shifted to the red because
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of this we can for example calculate our
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velocity relative to the Cosmic
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Microwave Background the Doppler effect
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is named after the Austrian physicist
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Christian Doppler and has nothing to do
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with the german word double ganger 9 the
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butterfly effect even a tiny change like
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the flap of a butterfly's wings can make
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a big difference for the weather next
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Sunday this is the butterfly effect as
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you have probably heard of it but Edward
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Lorenz actually meant something much
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more radical when he spoke of the
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butterfly effect he meant that for some
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nonlinear systems you can only make
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predictions for a limited amount of time
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even if you can measure the tiniest
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perturbations to arbitrary accuracy I
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explained this in more detail in my
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earlier video 8 the Meissner oxenfurt
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effect the Meissner oxenfurt effect is
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the impossibility of making a magnetic
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field enter a superconductor it was
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discovered by Volta Meisner and his
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postdoc Robert oxenfurt in 1933
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thanks to this effect if you try to
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place a superconductor on the magnet
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it will hover above the magnet because
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the magnetic field lines cannot enter
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the superconductor I assure you that
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this has absolutely nothing to do with
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yogic flying 7 the aharonov-bohm effect
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ok I admit that this is not a
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particularly well known effects but it
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should be the aharonov-bohm effect says
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that the wave function of a charged
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particle in an electromagnetic field
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obtains a phase shift from the potential
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of the background field I know that this
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sounds abstract but the relevant point
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is that it's the potential that causes
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the phase shift not the field in
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electrodynamics the potential itself is
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normally not observable but this phase
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shift in the aharonov-bohm effect can
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and has been observed in interference
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patterns and this tells us that the
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potential is not merely a mathematical
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tool before the aharonov-bohm effect one
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could reasonably question the physical
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reality of the potential because it was
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not observable 6 the tennis record
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effect if you throw any 3-dimensional
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object with the spin then the spin
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around the shortest and longest axis
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will be stable but that around the
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intermediate third axis not the typical
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example for the spinning object is a
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tennis record hence the name it's also
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known as the intermediate axis theorem
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or the Johnny bokov effect you see a
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beautiful illustration of the
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instability in this little clip from the
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International Space Station 5 the Hall
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effect if you bring a conducting plate
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into a magnetic field then the magnetic
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field will affect the motion of the
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electrons in the plate in particular if
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the plate is orthogonal to the magnetic
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field lines you can measure a voltage
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flowing between the opposing ends of the
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plate and this voltage can be measured
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to determine the strength of the
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magnetic field this effect is named
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after Edwin Hall if the plate is very
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thin the temperature very low and the
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magnetic field very strong you can also
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observe that the Condor
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Tivoli makes discrete jumps which is
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known as the quantum Hall effect for the
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hawking effect Stephen Hawking showed in
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the early 1970s that black holes emit a
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thermal radiation was a temperature that
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is inversely proportional to the black
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hole's mass this Hawking effect is a
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consequence of the relativity of the
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particle number an observer falling into
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a black hole would not measure any
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particles and think the black hole is
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surrounded by vacuum but an observer far
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away from the black hole would think the
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horizon is surrounded by particles this
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can happen because in general relativity
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what we mean by a particle depends on
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the motion of an observer like the
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passage of time a closely related effect
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is the Unruh effect named after Bill
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Unruh which says that an accelerated
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observer in flat space will measure a
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thermal distribution of particles with
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the temperature that depends on the
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acceleration again that can happen
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because the accelerated observers
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particles are not the same as the
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particles of an observer at rest three
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the photoelectric effect when light
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falls on a plate of metal it can kick
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out electrons from their orbits around
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atomic nuclei this is called the
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photoelectric effect the surprising
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thing about this is that the frequency
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of the light needs to be above a certain
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threshold just what the threshold is
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depends on the material but if the
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frequency is below the threshold it does
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not matter how intense the light is it
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will not kick out electrons the
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photoelectric effect was explained in
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1905 by Albert Einstein who correctly
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concluded that it means the light must
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be made of quanta whose energy is
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proportional to the frequency of the
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light to the Casimir effect everybody
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knows that two metal plates were tracked
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each other if one plate is positively
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charged and the other one negatively
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charged but did you know the plates also
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attract each other if they are uncharged
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yes they do this is the Casimir effect
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named after Hendrik kasnian it is
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created by quantum fluctuations that
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create a pressure even in vacuum this
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pressure is lower between the plates
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than outside of them so that the two
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plates are pushed towards each other
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however the force from the Casimir
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effect is very weak and can be measured
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only at very short distances one the
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tunnel effect definitely my most
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favorite effect quantum mechanics allows
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the particle that is trapped and
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potential to escape this would not be
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possible without quantum mechanics
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because the particle just does not have
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enough energy to escape however in
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quantum mechanics the wavefunction of
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the particle can leak out of the
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potential and this means that there is a
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small but nonzero probability that a
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quantum particle can do the seemingly
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impossible that's it for today thanks
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for watching see you next week