5 ms·

Depends how you measure it. Any X kg/lbs of matter here on earth is still that same X kg/lbs everywhere in the universe. Assuming the scale being used to weight

by Hamcha 4y ago

Depends how you measure it. Any X kg/lbs of matter here on earth is still that same X kg/lbs everywhere in the universe. Assuming the scale being used to weight is correctly calibrated to whatever planet it's in, it would still show up as the same amount of kg/lbs.

a9h74j 4y ago
Depends upon what you set out to measure. lbs is specifically a unit of force. kg is specifically a unit of mass. It is a category error to equate these as measures, although (in many places) an everyday convention to do so on Earth. IIRC the English unit for mass is the slug. If the tecnical limit is 70lbs or so, that is must technically be read as lbs force -- aka force of gravity which varies with location.
- rzzzt 4y ago
  Kilopond or kilogram-force is the force with which a 1 kg object is pushing on its base: https://en.wikipedia.org/wiki/Kilogram-force https://en.wikipedia.org/wiki/Kilogram-force
- dragonwriter 4y ago
  > lbs is specifically a unit of force Incorrect. The avoirdupois pound (lb) is historically a unit reflecting the long conflation of mass and force, but the modern unit of that name is expressly a mass unit that is a derived unit of the kilogram. The corresponding unit for force is the pound-force, (lbf).
- zmgsabst 4y ago
  Wikipedia lists it as a unit of mass — as defined by the amount that exerts a certain force. https://en.wikipedia.org/wiki/Pound_(mass) https://en.wikipedia.org/wiki/Pound_(mass) The pound unit of force is abbreviated ‘lbf’. https://en.wikipedia.org/wiki/Pound_(force) https://en.wikipedia.org/wiki/Pound_(force)
- jrochkind1 4y ago
  you could really take USPS for a ride by shipping something to Venus!
grog454 4y ago
"a teaspoon of neutron star material would weigh around a billion tonnes." https://astronomy.swin.edu.au/cosmos/n/neutron+star#:~:text=Neutrons%20stars%20are%20extreme%20objects,weigh%20around%20a%20billion%20tonnes https://astronomy.swin.edu.au/cosmos/n/neutron+star#:~:text=....
- droopyEyelids 4y ago
  It would be impossible to put neutron star material inside a cardboard box, and the original post was talking about possibility.
  - ben_w 4y ago
    If I remember right, given that free neutrons aren’t stable and have a very short half life, it would be explosively unwise even if it was physically possible.
    - deepspace 4y ago
      Yes, a free neutron decays to a proton, an electron and an electron neutrino with a half life of 879 seconds. This decay releases 0.8MeV of energy (mostly in the form of kinetic energy of the electron). My back of the envelope calculation shows that 1 gram of neutronium (approximately a mole) will release 43MW of energy continuously. Multiply that by 10^14 (the number of grams of neutronium per teaspoon) and the resultant energy release would be unimaginably huge. 'Explosively' does not even begin to describe it.
  - grog454 4y ago
    Actually, it too was talking about impossibility (see title); a much stronger assertion and usually wrong.
midasuni 4y ago
I assume they were saying Densest material on earth There are denser materials, but you would struggle to send them via UPS
tialaramex 4y ago
This is why simple balances are such a brilliant idea despite their simplicity. You don't need to calibrate to the local conditions, if I have a 250g mass on one side, and I put something on the other side and it balances, that's 250 grams, done. Only the (often provided with the balance) prototype masses need to be calibrated and that can be done by experts far from your local environment. Until as recently as 2019 this approach - using a prototype - was the only extant mass definition, the prototype kilogram lived at a specialised laboratory and its clones were used around the world to define mass (yes including the pound if you're an American). [ Today instead the Planck constant is defined to be exactly 6.62607015×10^−34 kg x m^2 per second and it's possible to build devices such as a Kibble balance to estimate what the kilogram is from knowing this definition, the better your Kibble balance the better the estimate ]

by Hamcha 4y ago

a9h74j 4y ago

Depends upon what you set out to measure. lbs is specifically a unit of force. kg is specifically a unit of mass. It is a category error to equate these as measures, although (in many places) an everyday convention to do so on Earth. IIRC the English unit for mass is the slug. If the tecnical limit is 70lbs or so, that is must technically be read as lbs force -- aka force of gravity which varies with location.

rzzzt 4y ago
Kilopond or kilogram-force is the force with which a 1 kg object is pushing on its base: https://en.wikipedia.org/wiki/Kilogram-force https://en.wikipedia.org/wiki/Kilogram-force
dragonwriter 4y ago
> lbs is specifically a unit of force Incorrect. The avoirdupois pound (lb) is historically a unit reflecting the long conflation of mass and force, but the modern unit of that name is expressly a mass unit that is a derived unit of the kilogram. The corresponding unit for force is the pound-force, (lbf).
zmgsabst 4y ago
Wikipedia lists it as a unit of mass — as defined by the amount that exerts a certain force. https://en.wikipedia.org/wiki/Pound_(mass) https://en.wikipedia.org/wiki/Pound_(mass) The pound unit of force is abbreviated ‘lbf’. https://en.wikipedia.org/wiki/Pound_(force) https://en.wikipedia.org/wiki/Pound_(force)
jrochkind1 4y ago
you could really take USPS for a ride by shipping something to Venus!

grog454 4y ago

"a teaspoon of neutron star material would weigh around a billion tonnes." https://astronomy.swin.edu.au/cosmos/n/neutron+star#:~:text=Neutrons%20stars%20are%20extreme%20objects,weigh%20around%20a%20billion%20tonnes https://astronomy.swin.edu.au/cosmos/n/neutron+star#:~:text=....

droopyEyelids 4y ago
It would be impossible to put neutron star material inside a cardboard box, and the original post was talking about possibility.
- ben_w 4y ago
  If I remember right, given that free neutrons aren’t stable and have a very short half life, it would be explosively unwise even if it was physically possible.
  - deepspace 4y ago
    Yes, a free neutron decays to a proton, an electron and an electron neutrino with a half life of 879 seconds. This decay releases 0.8MeV of energy (mostly in the form of kinetic energy of the electron). My back of the envelope calculation shows that 1 gram of neutronium (approximately a mole) will release 43MW of energy continuously. Multiply that by 10^14 (the number of grams of neutronium per teaspoon) and the resultant energy release would be unimaginably huge. 'Explosively' does not even begin to describe it.
- grog454 4y ago
  Actually, it too was talking about impossibility (see title); a much stronger assertion and usually wrong.

midasuni 4y ago

I assume they were saying Densest material on earth There are denser materials, but you would struggle to send them via UPS

tialaramex 4y ago

This is why simple balances are such a brilliant idea despite their simplicity. You don't need to calibrate to the local conditions, if I have a 250g mass on one side, and I put something on the other side and it balances, that's 250 grams, done. Only the (often provided with the balance) prototype masses need to be calibrated and that can be done by experts far from your local environment. Until as recently as 2019 this approach - using a prototype - was the only extant mass definition, the prototype kilogram lived at a specialised laboratory and its clones were used around the world to define mass (yes including the pound if you're an American). [ Today instead the Planck constant is defined to be exactly 6.62607015×10^−34 kg x m^2 per second and it's possible to build devices such as a Kibble balance to estimate what the kilogram is from knowing this definition, the better your Kibble balance the better the estimate ]