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Puzzling Questions

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  Puzzling Questions ram@zedat.fu-berlin.de (Stefan Ram) - 2026-09-10 08:49 +0000
    Re: Puzzling Questions richard@cogsci.ed.ac.uk (Richard Tobin) - 2026-09-10 10:26 +0000
    Re: Puzzling Questions ram@zedat.fu-berlin.de (Stefan Ram) - 2026-09-17 09:26 +0000
      Re: Puzzling Questions Phil Carmody <pc+usenet@asdf.org> - 2026-09-30 23:33 +0300

#28071 — Puzzling Questions

  I hope these are on-topic here, even though they are more about
  physics than about math. However, one does not need to learn
  physics now as everthing needed to answer is already given
  in the questions or should be known from high-school I think.

  The answers could be somewhat controversial, but I think that
  there really is one single correct answer. However, it might
  not be accepted as correct by everyone.

  "E = mc^2" does /not/ mean that energy (E) can be converted
  into mass (m), but rather that mass is always conserved.
  Can you see why? ("c" is a constant, the speed of light.)

  A manufacturer of tea bags says on the external packaging [1],
  "Always pour bubbling boiling water over it and let it steep
  for 6 minutes! Only then will you get a safe food product!"
  - Can you see the error in the time requirement of 6 minutes?

  [1] This is a real observation, the original German text reads:
  "Immer mit sprudelnd kochendem Wasser aufgießen und 6 Minuten
  ziehen lassen! Nur so erhältst du ein sicheres Lebensmittel!".

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#28072

In article <questions-20260910093009@ram.dialup.fu-berlin.de>,
Stefan Ram <ram@zedat.fu-berlin.de> wrote:

>  A manufacturer of tea bags says on the external packaging [1],
>  "Always pour bubbling boiling water over it and let it steep
>  for 6 minutes! Only then will you get a safe food product!"

You'd think it would be illegal to make false statements about
food safety on food packaging.

-- Richard

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#28076

ram@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:
>I hope these are on-topic here, even though they are more about
>physics than about math. However, one does not need to learn
>physics now as everthing needed to answer is already given
>in the questions or should be known from high-school I think.
>
>The answers could be somewhat controversial, but I think that
>there really is one single correct answer. However, it might
>not be accepted as correct by everyone.
>
>"E = mc^2" does /not/ mean that energy (E) can be converted
>into mass (m), but rather that mass is always conserved.
>Can you see why? ("c" is a constant, the speed of light.)

  Spoiler warning: This post now contains what I deem to be
  the correct answers.

  We know from high-school that energy is conserved, i.e.,
  constant. The speed of light also is constant. But when E
  is constant, c is constant, and E=mc^2, m also is constant!

>A manufacturer of tea bags says on the external packaging [1],
>"Always pour bubbling boiling water over it and let it steep
>for 6 minutes! Only then will you get a safe food product!"
>- Can you see the error in the time requirement of 6 minutes?

  This was actually herbal tea, but that should not matter for my
  following thoughts.

  When you end the steeping, you remove the bag from the hot water. If
  you do this after 6 minutes you make sure that the bag is sterilized.
  But that bag is not consumed. If you remove it after six seconds in-
  stead, you will still have to wait six minutes before the drink has
  cooled down from nearly 100 degrees Celsius, so the drink will be
  properly sterilized anyway, not matter when the bag is removed.

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#28090

ram@zedat.fu-berlin.de (Stefan Ram) writes:
> ram@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:
>>"E = mc^2" does /not/ mean that energy (E) can be converted
>>into mass (m), but rather that mass is always conserved.
>>Can you see why? ("c" is a constant, the speed of light.)
>
>   Spoiler warning: This post now contains what I deem to be
>   the correct answers.
>
>   We know from high-school that energy is conserved, i.e.,
>   constant. The speed of light also is constant. But when E
>   is constant, c is constant, and E=mc^2, m also is constant!

Energy isn't conserved. That was a naive pre-GR view.

The equations of motion are not invariant over time, therefore Noether's
theorem has no symmetry to work with, and provides no invariance law.

Phil
-- 
We are no longer hunters and nomads. No longer awed and frightened, as we have
gained some understanding of the world in which we live. As such, we can cast
aside childish remnants from the dawn of our civilization.
-- NotSanguine on SoylentNews, after Eugen Weber in /The Western Tradition/

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