unit 8: relativity

what was the pioneer 10 mission

the first spacecraft to reach escape velocity from the solar system

where is the nearest star

proxima centauri = 4.25 light years away

whats the fastest speed we've humans have reached

0.1% of the speed of light

what is the gravity assist maneuver

takes advantage of gravity and path of another planet around the sun to change heliocentric velocity

what is the cosmic speed limit

the speed of light

what is the special theory of relativity

the theory that motion is relative

what are the absolutes in the special theory of relativity

laws of nature are the same for everyone, speed of light is the same for everyone

what are some consequences of the special theory of relativity

loss of simultaneity, time dilation and length contraction

what is loss of simultaneity

two events happening at the same time depends entirely on the observers frame of reference

what is time dilation

time slows down as you approach the speed of light

what is length contraction

a moving object appears shorter as you approach the speed of light

what is the twin trip paradox

a traveling twin does not age as fast as stay at home twin

what is the lorentz factor

expresses how much measurements of time, length, and other physical properties change for an object while it moves

what is the lorentz factor formula

Y = 1/sqrt(1-v^2/c^2)

what is the time dilation formula

t = t0Y

t = time seen by observer

t0 = proper time (clock moving with object)

what is the length contraction formula

L = L0/Y

what is general relativity

gravity = the curvature of space time

what is spacetime

Spacetime is the four-dimensional combination of space and time that forms the "fabric" of our universe.

what are the consequences of general relativity

gravity time dilation and gravity lensing

what are tests of general relativity

mercury's orbit, light bending, gravitational redshift, shapiro delay

how does mercury's orbit test general relativity

mercury's orbit shifts by 43 arcsec/century, perfectly predicted by accounting for the Sun's warping of spacetime

how does light bending test general relativity

measuring how the path of starlight curves as it passes massive objects like the Sun, confirming Einstein's prediction that gravity warps spacetime, causing light to follow these curves

how does gravitational redshift test general relativity

light escaping gravity loses energy making it appear more red. predicted by Einstein's theory that time slows in stronger gravity

how does the shapiro delay test general relativity

Radar signals passing near a massive object take slightly longer to travel to a target and longer to return than they would if the mass of the object were not present.

what are gravitational waves

Ripples in spacetime caused by the acceleration of

masses e.g. core collapse of a massive star

what are black holes

A black hole is an object in space with gravity so strong that nothing, not even light can escape.

what is a wormhole

a hypothetical connection through hyperspace between two points in the universe

how many people would be needed to colonize another star

~5000 people

why do tides happen

due to the gravitational attraction that the Sun and Moon exert on Earth

what is the strength of tides formula

M/d^3

are lunar or solar tides stronger

lunar tides

when are tides the strongest

during a new or full moon

why is the earths rotation slowing

The friction from tides gradually slows Earth's rotation (2ms/century),

Why is the Moon receding from Earth?

Earth spins much faster than the Moon orbits. This rotation pulls the tidal bulges slightly ahead of the Moon in its orbit. these bulges have a gravitational pull, giving the moon a boost and pushing it into higher orbit, increasing its radius

Why is the moon tidally locked?

the constant tugging from Earth's gravity slowed the Moon's spin until it reached a stable state where its rotation period matched its orbital period. Now, the Moon takes the same amount of time to rotate on its axis as it does to orbit Earth

what is anchoring bias

the tendency to rely too heavily on one trait of info when making a decision

what is availability bias

the tendency to overestimate the likelihood of events with a greater availability in memory

what is confirmation bias

the tendency to remember, search for, or focus on info in a way that confirms preconceptions

what is egocentric bias

the tendency to rely too heavily on ones own perspective and/or perception of self relative to others

what is the ad hominem fallacy

a theory is discarded because of the person who argues it, not because of evidence against it

what is the affirming the consequent fallacy

If P then Q. Q occurred Therefore P also occurred

what is the begging the question fallacy

in arguing for a claim, the claim is already assumed in the premise

what is the denying the antecedent fallacy

If P then Q. Not P Therefore, not Q

what is the false dilemma fallacy

presenting a limited set of alternatives when there are others worth considering in the context

what is the red herring fallacy

the raising of some irrelevant issue that diverts attention from the main subject

where is pioneer 10 headed

for aldeberan, 68 light years away - will take 2 million years to get there

what spacecraft reached the fastest speed

Parker Solar probe

how did we reach the fastest speed?

using gravity assist from venus

what is the speed change with the gravity assist maneuver in the planets frame of reference

speed stays the same

what is the speed change with the gravity assist maneuver in the suns frame of reference

the probe gains (or loses) speed by tapping energy from the planet,

what is gravitational lensing

bending of light when light rays travel in a gravitational field

what is gravitational time dilation

clocks near a massive object run slow

what are the two most important parameters in the Parametrized post Newtonian formulas

• 𝛾: how much space curvature is produced by a unit mass  β: how much nonlinearity exists with multiple masses

• 𝛾=β=1

how much does GR predict light will bend around the sun

1.75 arcseconds

how fast do gravitational wave propagate

the speed of light