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J773YF Kitchenware on shelves with stainless steel sink in 17th century Kintyre stone cottage

What happens to the stains in my sink when I clean it with bleach?

11 September 2024

One reader wields the power of chemistry to answer this question - but concludes that elbow grease is probably the best approach to cleaning your sink
2H6020J Few pedestrians on the rather busy street in metaverse conceptual reality

This week’s new questions

11 September 2024

Why do animals like rhinoceros and triceratops have horns while deer and elk have antlers? And is there any scientific evidence disproving the notion we are all part of a vast simulation run by an advanced civilisation?
2CG262A Old fashioned street clock with Roman numerals without arrows on blue slightly cloudy sky background. Real view of street clock in city. Stopped time

What would happen if time stopped?

11 September 2024

Our readers consider this question from physical and philosophical perspectives, but mainly conclude: nothing
2JF72KW Digital hands reaching each other, artificial intelligence creativity concept

Will we ever be able to tell if an AI gains consciousness? Part 2

4 September 2024

Our readers have more thoughts on this issue, including what it would mean to buy or sell a conscious intelligence
hot Jupiter class exoplanet, gas giant planet lit by an alien sun (3d space rendering); Shutterstock ID 1150780133; purchase_order: -; job: -; client: -; other: -

This week’s new questions

4 September 2024

If an Earth-sized rogue planet passed through our solar system, missing the planets, how much disruption would it cause? And would it be possible for an intelligent species to develop an advanced technological civilisation without the wheel?
2DBWHRA A Atom with electrons and protons moving in the microcosmos.

Is there the same number of electrons as protons in the universe?

4 September 2024

This isn’t true for Earth, nor is it the case for the universe, explains one reader
2RXK2EN Catford Local Area Photography

What is the largest size an animal can be?

4 September 2024

Our readers explain the maximum size of a quadrupedal animal and consider the sizes of dinosaurs, blue whales and colonial organisms
Surrealism with a woman holding a mirror and covering her face in the field with a transparent background behind the mirror; Shutterstock ID 2153195107; purchase_order: -; job: -; client: -; other: -

How do I know if what I see is actually there?

28 August 2024

Our readers are impressed with our 10-year-old correspondent’s question, one they say has been asked for thousands of years - and one that requires a little philosophy to answer
This week’s new questions

This week’s new questions

28 August 2024

How do we know that gravity has the same speed as light? And why is this the case? Jonas Hermansson, Brösarp, Sweden
R1D8PY Silverback western lowland gorilla sitting down to eat at Zoo Atlanta in Atlanta, Georgia. (USA)

Could aliens work out if a human or an ape built a tomb? Part 2

28 August 2024

Further correspondence on this issue questions if the aliens would even be interested in the archaeology of the tomb

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