Effects of gravity in space (split from Length contraction in a block universe…)

[jday]

I wouldn't say that measurement itself is an illusion. Due to Earth's gravitational pull,  it directly effects the expansion of objects. It was recorded on March 2016, an astronomer Scott Kelly, grew 3 inches in space due to the lack of a gravitational pull. I would rather phrase that measurements is dependent on our external conditions, for example we have a basic unit system so that despite or own perspective we human can globally interpret our external conditions.  Therefore, if our conditions changed like a different planet than we would have to change our basic measurement system.  

[swansont]

!

Moderator Note

Split, as this has nothing to with the relativity question under consideration in the other thread

 

[Ghideon]

12 hours ago, jday said:

I wouldn't say that measurement itself is an illusion. Due to Earth's gravitational pull,  it directly effects the expansion of objects. It was recorded on March 2016, an astronomer Scott Kelly, grew 3 inches in space due to the lack of a gravitational pull. I would rather phrase that measurements is dependent on our external conditions, for example we have a basic unit system so that despite or own perspective we human can globally interpret our external conditions.  Therefore, if our conditions changed like a different planet than we would have to change our basic measurement system.  

I disagree with the conclusion. The currently used system of units allows us to design space probes and rowers that works predictably in micro gravity and on other planets. It sounds unnecessary complicated, from an engineering perspective, to plan and execute such missions if the units of measure depends on location.

 

Side note: confusion between metric and imperial units has caused at least one failure already; the Mars Climate Orbiter: 

Quote

The MCO MIB has determined that the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, “Small Forces,” used in trajectory models

Source: https://web.archive.org/web/20010920052120/http://sunnyday.mit.edu/accidents/MCO_report.pdf

 

[jday]

I understand that but would you design a space probes the same are now if you were on a planet with a denser gravitational pull?  Our weight is also different on different planets. 

 

[Ghideon]

54 minutes ago, jday said:

I understand that but would you design a space probes the same are now if you were on a planet with a denser gravitational pull?  Our weight is also different on different planets. 

 

That is a different question, not related to system of units. If I, the designer, was located somewhere where gravitation is different than on earth it would not affect the design of a space probe; the design would be determined by the space probe mission and not my location. If the space probe would be operating on a planet with different gravitation than earth that would have an effect on the design. I have not studied space probe design enough to have any detailed opinion how to design for a planet more massive than earth but intuitively it would be more difficult to land softly and harder to launch into space from the planet's surface. I would have to take that into account when planning the mission, its objectives and designing the probe and other systems. And in all the cases above I would use our current system of units (metric or imperial but not a mix of them).

Edited November 17, 2021 by Ghideon

[MigL]

The astronaut actually 'grew' 3 inches, but the inch unit stayed the same; there was no dilation of length in lessened gravity.
What actually happened is that, his body, exposed to a prolonged period of lessened gravity, de-compacted, and his joints moved apart.
I myself am usually 1/2 inch taller in the morning ( after having slept horizontally )than in the evening ( after standing most of the day ).
Sometimes the difference is enough that I have to adjust the rear-view mirror in my vehicle.

[beecee]

1 hour ago, jday said:

I understand that but would you design a space probes the same are now if you were on a planet with a denser gravitational pull?  Our weight is also different on different planets. 

 

The only differences would be more power to put a proble into orbit, and better and more efficient methods of slowing a craft upon entering the atmopshere for a landing.

[jday]

Throughout the centuries the SI unit has proved to be unreliable in certain situations hence in those situations they decided to improve and change the basic unit system. We base measurements from earth’s properties but given the different and probably infinite possibilities within our universe we base our observations from earths basic units however one size does not fit all. Connecting back to my initial statement I wouldn’t say that measurement itself is an illusion but there are variable factors that change the aspect and how we interpret the information. 

[Genady]

8 minutes ago, jday said:

Throughout the centuries the SI unit has proved to be unreliable in certain situations hence in those situations they decided to improve and change the basic unit system. We base measurements from earth’s properties but given the different and probably infinite possibilities within our universe we base our observations from earths basic units however one size does not fit all. Connecting back to my initial statement I wouldn’t say that measurement itself is an illusion but there are variable factors that change the aspect and how we interpret the information. 

"Centuries"? It is only 62 years in existence.

[jday]

They must’ve been a confusion in the 19 century the SI units were revised and in the 16th century it was once revised again I can link and article if you’d like.

[Genady]

6 minutes ago, jday said:

They must’ve been a confusion in the 19 century the SI units were revised and in the 16th century it was once revised again I can link and article if you’d like.

No need, it's ok. They didn't call it SI then, I guess.

[jday]

Yeah “In 1668 John Wilkins, an English clergyman, proposed a coordinated system of units of measure use by philosophers.”  

The French originated the metric system of measurement (now called the International System of Units and abbreviated SI, pronounced “ess-eye”) it was revered to a different term.