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Time | SciByte 2

chris — Wed, 01 Jun 2011 03:00:15 +0000

We spend some time looking at time, how we have measured it’s passage throughout history, philosophically, how it’s affected by gravity, and the very concept of time itself.

Plus find out why Einstein proposes that we travel through time at the speed of light, how Atomic clocks work, and is it possible gravitational fields warp time?

All that and more, on SciBye!

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Show Notes:

Concept:

“Time is what keeps everything from happening at once.” – Ray Cummings, Sci-Fi Author

Measurement:

Smallest units of time = Planck time [time it takes for light to travel the shortest distance current theories can handle]

Philosophy:

Why do we always move forward?

Scientific:

Is time eternal, or a side effect of “space”?

Philosophy on the Nature of Time:

Immanuel Kant believes time is all in our heads, as a necessity to quantify sensory inputs of everyday existence. Also believes in predestination, and that Free Will can only exist outside of Time.
Martin Heidegger believes similarly, and that humans should be capable of “stepping out of time” by a specific form of non-associative thinking. The past, present and future can become one within our minds, and experienced in random order. (uhm, excuse me?!?)
Henri Bergson believed that Time could not be measured because it is infinite and malleable, and shapes itself to the perceptions of an individual.
“Time is an illusion” is a common saying in Buddhist teachings.
HG Wells: “There is no difference between time and any of the three dimensions of space except that our consciousness moves along it.” — The Time Machine
C. S. Lewis “The future is something which everyone reaches at the rate of 60 minutes an hour, whatever he does, whoever he is.” (but do those min pass by at the same rate)

‘When’ was the Start of the Universe, T=0 point

- Red Shift / Blue Shift – Doppler Effect light waves act similar to sound waves coming towards you or away from you. Blue shift = Away; Red shift = Near
- Type 1A Supernova – PIC – To judge distance and speed [red shift/blue shift]
- Roughly 13.7 Billion Years ago

Measurement ‘devices’ through history

- Mayan’s : Mayan Calender created during the Dark Ages in Europe

Calculated

Earth orbit @ 365 days [Actual = 365.2422 days, 0.06%]
Lunar Month @ 29.53086 days [Actual = 29.53059 days; 0.0009%]
Mercury orbit @ 117 days [Actual = 116 days; 0.86%]
Venus orbit @ 584 days [Actual = 583.92 days; 0.01%]
Mars orbit @ 780 days [actual = 779.936 days; 0.008%]

Antikythera mechanism – is an ancient mechanical computer designed to calculate astronomical positions. It was recovered in 1900–1901 from the Antikythera wreck. Its significance and complexity were not understood until decades later. Its time of construction is now estimated between 150 and 100 BC. The degree of mechanical sophistication is comparable to a 19th century Swiss clock. Technological artifacts of similar complexity and workmanship did not reappear until the 14th century, when mechanical astronomical clocks were built in Europe

A day – 24 hours?

2 Radio telescope set on different points of Earth measure a radio wave from a quasar. They line up once a ‘day’ which is not always 24 hours [changes are in mili seconds]

Atomic Clocks

- In certain elements [like Cesium] the Electrons will ‘jump’ between orbits and emit a flash of light at precise intervals [Cesium, 9 billion times a sec] Video
- Such a clock, if sent on a space shuttle, ticks at a different speed. Because it is further from Earth’s gravitational pull.

EINSTEIN:

- Einstein proposes that we travel through Time at the speed of light.
- Einstein: Spacetime is a single entity, not separate things. And because of the mixing of space & time, time ticks differently for separate entities, based on relative speeds.
- The faster you travel through space, the slower you travel through time.
- Proven by the Shapiro effect (blip in Mercury’s orbit, measured on opposite sides of the Sun)

Shapiro Effect

Gravitational fields warp time
blip in Mercury’s orbit, measured on opposite sides of the Sun – VIDEO

If time is flexible based on observation, then all of it always exists…

- (Incorrect for quantum mechanics)
- New theories suggest that “spacetime” is granular, and not fixed. On a large scale it looks like a single thing, but it actually flows as it is being created, in the future.

Black holes actually STOP time at their event horizon, to an outside observer.
But an observer falling in would see time speed up around them, the closer they got.

Time Travel?
High speed camera moments
Lighter

Busting Water Baloon

Additional Information
CPT – Charge, Parity, and Time Reversal (CPT) Symmetry

WIKI – Shapiro Delay

What Time Is It? (part 1 // part 2 // part 3 // part 4)

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Gravity | SciByte 1

chris — Tue, 24 May 2011 23:24:32 +0000

This week on SciByte …
We look at the results from Gravity Probe B and how they relate to Einstein’s predictions on mass, space, time and how they all interact with one another. We’ll also open up the guts of that crazy contraption, and discuss some of the impressive tech that made the whole experiment possible to begin with.

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Show Notes:

Gravity?

-Sir Issac Newton [Mathematician]
-1687 – His predictions predicted the existence of Neptune based on the motions of Uranus
-Mercury’s Orbit hower can NOT be explained by Newtonian math alone, but was resolved with Einsteins general theory of relativity in 1915
-Newtonian Calculations however still are accurate enough for most applications
-General Relativity – Albert Einstein [1907-1915] The observed gravitational attraction between masses results from their warping of space and time.
→ Space-Time is not flat, but can be stretched and warped by matter
-What this means, boiled down: Time moves slower under gravity

Gyroscope

-A device for measuring or maintaining orientation, based on the principles of conservation of angular momentum.
–Video : Gyroscope
–Video : Conservation of Angular Momentum : Spinning Skater

Gravity Probe A

-“A” confirmed the prediction that gravity slows the flow of time, and the observed effects matched the predicted effects to an accuracy of about 70 parts per million. [1976, and lasted <2hours]
-Used a hydrogen maser, a highly accurate frequency standard, to measure the rate change of a clock in lower gravity with high precision.

Gravity Probe B

-A star, a telescope, a spinning sphere [conceived in 1959, launched in 2004, decommissioned in Dec 2010] [A Star, telescope, and space time]
–Gravity Probe B Cutaway
-Reference telescope sighted on IM Pegasi, a binary star in the constellation Pegasus
-Drag Free System
-Solar Radiation Pressure – Particles streaming away from Sun transferring momentum
-Atmospheric Drag [@624KM]
-Compensation done with helium boosters, full 6-degree motion (first ever)
-London moment gyroscopes
-A spinning superconductor generates a magnetic field whose axis lines up exactly with the spin axis of the gyroscopic rotor.
-Are housed in a dewar of superfluid helium @ a temperature of under 2 kelvins (−271 °C, −456 °F)
-A magnetometer determines the orientation of the generated field, which is interpolated to determine the axis of rotation.

** The pointer shifted by just 6,000 milliarcseconds — the width of a human hair as seen from 10 miles away
* At the time, the gyroscopes were the most nearly spherical objects ever made.

~ size of ping pong balls, they are perfectly round to within forty atoms
– Scaled to the size of the Earth, the elevation of the entire surface would vary by no more than 12 feet
* Measured changes in gyroscope the equivalent to an angular separation the width of a human hair viewed from 32 kilometers (20 miles) away over a one-year period. [0.5 milliarcseconds (1.4×10−7 degrees)]

Already Proven?

The Apollo astronauts left retro-reflector mirrors on the Moon, and laser ranging from Earth can now track their positions to millimeters. At that level of precision, the Moon’s motion in orbit has confirmed gravitomagnetism, the source of frame-dragging, to 0.15%, or 130 times better than GP-B.

Precision measurements of the Shapiro effect or gravitational time delay for light, most recently in 2002 by the Cassini space probe

Gravity – no uniform model for all scales

The laws of classical Newtonian physics remain accurate in predicting the behavior of the vast majority of large objects—of the order of the size of large molecules and bigger—at velocities much smaller than the velocity of light

Quantum mechanics

-By Newtonian Standards Atoms can’t exist
-Newtonian physics says that electrons would fall out of orbit into the nuclues
-Electron Orbits in actuality can only exist as very specific points
-Heisenburg Uncertainty principle – can’t know location AND speed

Black holes

-First conceptualized in 1783 by Henry Cavendish
-Infinite Density; Event Horizon [point of no return]

Dark Matter

-Matter that is inferred to exist from gravitational effects on visible matter and background radiation, but is undetectable by emitted or scattered electromagnetic radiation

Dark Energy

-Hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe
–Dark Matter/Dark Energy Estimates
-Some estimates state The Universe is made up of 23% Dark Matter; 72% Dark Energy; and Atoms a mere 4.6%

Additional Information :

SPACETIME: From the Greeks to Gravity Probe B
NASA : Gravity Probe B
Sky&Telescope : Gravity Probe B: Relatively Important?
PC Magazine : It Took More Than 50 Years, But NASA Proves That Einstein Was Correct Scientific American : Earth’s Mass and Motion Warps Spacetime as Einstein Said
engadget : NASA concludes Gravity Probe B space-time experiment
National Geographic : Einstein Theories Confirmed by NASA Gravity Probe
NASA Gravity Probe Confirms Two Einstein Theories
Wired : Floating Gyroscopes Vindicate Einstein
spaceRef : NASA’s Gravity Probe B Confirms Two Einstein Space-Time Theories
PCWorld:Experiment Confirms Space-Time Vortex Around Earth, Makes Our Heads Hurt
What’s 96 Percent of the Universe Made Of? Astronomers Don’t Know
YouTube | Lecture 1 | Modern Physics: Quantum Mechanics (Stanford)

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