# [2nd Zoom Session] The Structure of Spacetime and Sizing up Black Holes

(Feel free to join us 30 minutes earlier to chat and set up your Zoom before we start the session!)

In this meeting we’ll be discussing:

The Structure of Spacetime: This module will explore relativity. We look at the many ways black holes affect the universe around them from discussions of reference frames through to the change in the passage of time as you approach a black hole.

Sizing up Black Holes: In this module students will explore the various sizes of black holes and their measurable properties. Students will learn that there are four major types of astrophysical black holes (primordial/mini black holes, stellar mass, intermediate-mass and supermassive black holes), and discover current theories on their formation, and what might feed them.

See you there, bye!

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Recording: here.
Slides: here.

@Fabio

@sonal

@hhliu The paper announcing the discovery of pulsars had five authors. Bell’s thesis supervisor Antony Hewish[5][6] was listed first, Bell second. Hewish was awarded the Nobel Prize, along with the astronomer Martin Ryle. At the time fellow astronomer Sir Fred Hoyle criticised Bell’s omission.[12][13][14] In 1977, Bell Burnell commented, “I believe it would demean Nobel Prizes if they were awarded to research students, except in very exceptional cases, and I do not believe this is one of them.”[15] The Royal Swedish Academy of Sciences, in its press release announcing the prize,[16] cited Ryle and Hewish for their pioneering work in radio-astrophysics, with particular mention of Ryle’s work on aperture-synthesis technique and Hewish’s decisive role in the discovery of pulsars.

@Fabio Space-Time Around Black Holes Visualized Space-Time Around Black Holes Visualized | Space

@sonal Black hole whirlpool: A spinning black hole is more like a whirlpool than a pothole. The swirling water in this analogy is spacetime itself. It’s pulled around as the black hole rotates. This region of twisted spacetime is called the ergosphere. … That energy can be tapped into and transferred to other things in the black hole’s environment

@Shambhavi for speed to stay constant, and we’re seeing distance being covered, it’s the time that slows/fastens. (speed is distance by time)

• then you’re moving with light, nothing changes

@sakshamsrivas2679756 Exactly tho why does speed of light always has to stay constant
-if you move at speed of light time stops

@sonal Speed of light the speed at which electromagnetic waves travel through the vacuum of space – and its value can be predicted by equations unifying our understanding of electricity and magnetism, as discovered over 150 years ago by the Scottish physicist and mathematician James Clerk Maxwell.

@Shambhavi it takes billions of years for light from stars to reach us, and therefore the stars we’re seeing today, that light was emitted billions of years ago. we’re seeing billions of years into the past when we look at stars. for us the stars are still billions of years in the past.
-of course in reality, that star may long have died in real time

@antoinettegre2608987 Definition of a computer: “A million morons working at the speed of light” (David Ferrier)

@hhliu Supplemental videos about speed of light

The Speed of Light is NOT About Light

@Shambhavi Think of space as all the space you can cover distance in (the first three dimensions). Because time and distance are related in order to let speed (of light stay constant), the space-time is all the four dimensions.

@sakshamsrivas2679756

@sakshamsrivas2679756

@hhliu

Eugene’s videos are great

This is the same paradox, just with a ladder and garage instead of a train and tunnel:

@Mervyn Super-massive black holes in the centers of some active galaxies create powerful jets of radiation and particles travelling close to the speed of light. Attracted by strong gravity, matter falls towards the central black hole as it feeds on the surrounding gas and dust. But instead of falling into the black hole, a small fraction of particles get accelerated to speed almost as great as the speed of light and spewn out in two narrow beams along the axis of rotation of the black hole. These jets are believed to be the sources of the fastest-travelling particles in the Universe

https://www.nature.com/articles/d41586-021-03659-0

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Found this really amazing demonstration of mass and gravitational effects on the space-time “fabric”!
https://youtu.be/MTY1Kje0yLg

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