Antimatter Storms and the Universe's Dark Ages
This month on Naked Astronomy, we discover the streams of antimatter coming from lightning on Earth, and find out how to study the stars that ended the dark ages and brought light to the universe. We hear about Jupiter's role in Earth asteroid impacts, Cassini's flypast of Saturn's moon Rhea and the first science results from the Planck mission. Plus, your questions on light speed route planning, outrunning sunset and why the solstice doesn't coincide with the earliest dawn!
In this episode
01:38 - SDSS - The Largest Colour Image of the Sky Ever Made
SDSS - The Largest Colour Image of the Sky Ever Made
The Sloan Digital Sky Survey-III has released some incredible images of the night sky, and announced plans to image even more. Now, the first catalogues of spectroscopy results have been released online, allowing anyone to access this enormous collection of data...
04:48 - Jupiter's Role in Asteroid Impacts
Jupiter's Role in Asteroid Impacts
Does Jupiter protect Earth from asteroid impact? A new study evaluates the myth that the giant planet acts as our protector, gravitationally slinging asteroids out of a collision course...
07:52 - Rhea Gets the Cassini Flypast Treatment
Rhea Gets the Cassini Flypast Treatment
NASA's Cassini spacecraft has completed an extremely close flyby of Saturn's moon Rhea, returning incredible pictures that allow us an unprecidented view of the surface features - including faults reminiscent of Enceladus' "Tiger Stripes"...
10:57 - First Planck Science Results
First Planck Science Results
This month, researchers working on the Planck project released their first science data - including new galaxy clusters and clouds of cold gas in the Milky Way. Plus, they announcea greater than expected data loss rate from cosmic rays - helping to plan future missions...
15:20 - The incredible and erratic behaviour of Red Dwarfs
The incredible and erratic behaviour of Red Dwarfs
Red Dwarf stars seem to be far more active than previously thought - good news for astronomers, but terrible news for any habitable planets around them...
19:11 - 2000th Comet Spotted by SOHO
2000th Comet Spotted by SOHO
Data from the Solar and Heliospheric Observatory, or SOHO, has been used by amateur astronomers worldwide to spot comets. Over half of all known comets have been spotted in this way, and now a student in Poland has spotted SOHO's 2000th comet!
21:54 - Fact Impact: Relativity
Fact Impact: Relativity
with Andrew Pontzen
- Relativity was born in 1905 when Albert Einstein published a seminal work titled "on the electrodynamics of moving bodies".
As that name suggests, Einstein analysed the electronic behaviour of particles moving at high speed...- …but he realised that the implications of his theory extended way beyond that original motivation.
- In the same year that Einstein laid this ground-work for relativity...
- …he also discovered a crucial foundation of quantum theory...
- …explained how a bit of dust moves around in the air, by constant bombardment from microscopic air molecules
- …and used his new "relativity" theory to show that E = mc2.
- It was the lesser-known Hermann Minkowski who later showed that Einstein's ideas could be expressed in the beautiful mathematical language of spacetime
- Einstein went on to spend eight years worrying that Newton's laws of gravity were not compatible with Minkowski's spacetime...
- …ultimately leading to Einstein's 1915 paper which introduced "general" relativity, a new version of gravity...
- …that was not only compatible with, but actually founded on, Minkowski's idea of spacetime.
- Einstein predicted a whole slew of counterintuitive effects from his relativity theories...
…if you travel at 100 miles per hour for 100 years, your watch will lose 35 microseconds compared to an identical watch left stationary- …but if you sit still for 100 years on a stepladder 100 metres tall, the tiny difference in gravity means your watch will gain 35 microseconds compared to an identical watch on the ground
- …So, clocks on high-altitude orbiting satellites should lose 7 microseconds per day because they're orbiting so fast
- …but should gain 45 microseconds per day because they're so high up, so an overall gain of 38 microseconds per day
- …被验证的预测gain and again in experiments, and is actually used every time a satellite navigation system calculates its location.
- General relativity is the key building-block in our modern understanding of space and the universe
- …it explains why mercury's orbit does not quite agree with the prediction from Newton's gravity...
- …it correctly describes how the path of light is bent when it passes near massive objects - everything from stars to galaxy clusters
- …it predicts gravitational waves, the existence of which have been indirectly confirmed by watching how the rate of a pulsar changes over time...
- …it gives us a framework to describe the universe from a tiny fraction of a second through to today, 13.6 billion years...
- …for instance describing precisely how the overall expansion of the universe is affected by the gravitational pull of matter within the universe...
…leading to exact predictions which match the real universe in exquisite detail.- But relativity cannot be a complete theory of spacetime and gravity...
- …the combination of Einstein's original relativity theory with quantum mechanics gives quantum field theory, the incredibly successful theory of fundamental particles
- …but the combination of general relativity with quantum mechanics leads to mathematical nonsense
- …meaning that gravity cannot be accommodated within quantum mechanics
- …which troubled Einstein for the rest of his life
- …and has led to a myriad of speculative mathematical ideas like string theory and loop quantum gravity
- …none of which have yet been experimentally confirmed or rejected by cosmologists or physicists.
As that name suggests, Einstein analysed the electronic behaviour of particles moving at high speed...
…if you travel at 100 miles per hour for 100 years, your watch will lose 35 microseconds compared to an identical watch left stationary
…leading to exact predictions which match the real universe in exquisite detail.How fast does gravity propagate?
Is it possible to plot a clear course when travelling at light speed?
32:29 - Antimatter from Terrestrial Thunderstorms
Antimatter from Terrestrial Thunderstorms
with Michael Briggs, University of Alabama, Huntsville
Gamma ray flashes seemingly coming from thunderstorms have been a mystery since first being identified in 1994. Now, using the Gamma Ray Burst Monitor on the Fermi satellite, researchers have identified the cause as beams of antimatter streaming out into space. Louise Ogden spoke to Michael Briggs to find out more...
Why doesn't solar wind move dust on the moon?
Why doesn't the solstice coincide with the earliest dawn?
43:02 - Studying the Remains of the First Stars
Studying the Remains of the First Stars
with Ryan Cooke, Cambridge University
The first stars ended the dark ages of the universe pouring heat, light and heavier elements into an otherwise cold, dark expanse. New research uses light from quasars to analyse the clouds left behind when some of these first stars exploded...
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