John Rennie

Chester, United Kingdom

http://www.ratsauce.co.uk

I did a PhD in solid state photochemistry then went on to work in industry as a colloid scientist. These days I work part time as a computer nerd, and answer questions on the Physics Stack Exchange to stop my brain from atrophying.

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Did the Big Bang happen at a point?

general-relativity cosmology big-bang black-hole-thermodynamics asked Sep 23, 2014 at 10:03

physics.stackexchange.com

162 votes

Does someone falling into a black hole see the end of the universe?

general-relativity black-holes spacetime observers event-horizon asked Oct 29, 2013 at 13:25

physics.stackexchange.com

107 votes

What is the proper way to explain the twin paradox?

special-relativity time reference-frames relativity asked Mar 7, 2016 at 16:22

physics.stackexchange.com

105 votes

What is time, does it flow, and if so what defines its direction?

thermodynamics special-relativity time entropy arrow-of-time asked Feb 12, 2016 at 11:12

physics.stackexchange.com

105 votes

How can time dilation be symmetric?

special-relativity inertial-frames coordinate-systems time-dilation observers asked Jan 30, 2018 at 17:09

physics.stackexchange.com

81 votes

What is time dilation really?

special-relativity time-dilation asked Mar 6, 2016 at 9:18

physics.stackexchange.com

64 votes

What did the Democrats have to gain by ousting Kevin McCarthy?

united-states house-of-representatives democratic-party speaker asked Oct 4 at 11:33

politics.stackexchange.com

59 votes

Does time move slower at the equator?

special-relativity time-dilation asked Jul 17, 2014 at 11:48

physics.stackexchange.com

55 votes

How long would it take me to travel to a distant star?

homework special-relativity rocket-science space-travel asked Apr 24, 2014 at 6:08

physics.stackexchange.com

45 votes

Identification of particles and anti-particles

particle-physics standard-model definition antimatter conventions asked Oct 22, 2013 at 15:27

physics.stackexchange.com

Top Answers

564

Did the Big Bang happen at a point?

physics.stackexchange.com

349

Why are four-legged chairs so common?

physics.stackexchange.com

226

Why does ice cream get harder when colder?

physics.stackexchange.com

204

Why does Stephen Hawking say black holes don't exist?

physics.stackexchange.com

180

How can time dilation be symmetric?

physics.stackexchange.com

145

Why can't I wash away soapy hands?

travel.stackexchange.com

144

Why doesn't a nucleus-like body made up of just neutrons exist?

physics.stackexchange.com

141

Why doesn't water actually perfectly wet glass?

physics.stackexchange.com

128

How is 6W equivalent to 40W, as claimed by adverts for LED light bulbs?

physics.stackexchange.com

117

What is time, does it flow, and if so what defines its direction?

physics.stackexchange.com

115

Why doesn't the motion of a car affect the frequency of radio stations?

physics.stackexchange.com

112

Does juggling balls reduce the total weight of the juggler and balls?

physics.stackexchange.com

110

What is the connection between special and general relativity?

physics.stackexchange.com

110

What is the relation between electromagnetic wave and photon?

physics.stackexchange.com

110

Why is the period of a geostationary satellite not exactly 1440 minutes?

physics.stackexchange.com

107

When I boil a kettle, what stops all the water from turning (exploding!) in to steam in one go once it reaches 100°C?

physics.stackexchange.com

104

Why is 'Belgium' the rudest word in Hitchiker's Guide to the Galaxy?

scifi.stackexchange.com

102

Why does the Sun's (or other stars') nuclear reaction not use up all its "fuel" immediately?

physics.stackexchange.com

100

Is light actually faster than what our present measurements tell us?

physics.stackexchange.com

100

Could we send a man safely to the Moon in a rocket without knowledge of general relativity?

physics.stackexchange.com

Is there a frame of reference in which I was born before I was conceived?

physics.stackexchange.com

What is the proper way to explain the twin paradox?

physics.stackexchange.com

Why do the big nuts always remain at top? The Brazil-nut Effect

physics.stackexchange.com

What is time dilation really?

physics.stackexchange.com

Why do gases have weight?

physics.stackexchange.com

Why do shadows from the sun join each other when near enough?

physics.stackexchange.com

Why doesn't oil produce sound when poured?

physics.stackexchange.com

Why is 7 TeV considered as a big amount of energy?

physics.stackexchange.com

Why is Voyager 1 approaching Earth?

physics.stackexchange.com

Why do wet objects become darker?

physics.stackexchange.com