Gravity and fishing line.

In summary, Einstein discusses how special relativity and the equivalence principle lead to the idea that the Earth's orbit in the sun's gravitational field is a geodesic trajectory through a curved space-time. He poses a hypothetical scenario where the Earth is tethered to a fixed point instead of being in orbit, and wonders if the tether would also "influence and determine the metrical laws of the space-time continuum." However, there is no reason to believe that this would be the case.
  • #1
oldman
633
5
While introducing the equivalence principle in "The Meaning of Relativity" (6th ed. 1954, p.59), Einstein considered how special relativity requires that circular motion distort the ratio (pi) between the measured diameter and perimeter of a rotating circle, compared with its value in a non-rotating frame. He pointed out that the equivalence principle (which says that an accelerated frame with no gravitational field is equivalent to a non-accelerated frame with a gravitational field) then requires that "the gravitational field influences and even determines the metrical laws of the space-time continuum".

This (as I see it, faultless) reasoning can be extended to argue that the Earth's orbit in the sun's gravitational field is a geodesic trajectory through a (slightly) curved space-time.

But suppose (very hypothetically) that instead the Earth moved along its orbit while tethered to a fixed point (substituted for the sun) by a length of (very) strong fishing line.

Would one then be justified in arguing that the fishing line, by virtue of its electromagnetic-based cohesion, "influences and even determines the metrical laws of the space-time continuum" ?

And if not, why not?
 
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  • #2
oldman said:
Would one then be justified in arguing that the fishing line, by virtue of its electromagnetic-based cohesion, "influences and even determines the metrical laws of the space-time continuum" ?
No, There would be no reason such a scenario would have any effect on "metrical laws" as you put it. Space-time would continue to act as it always does, you'd just have to analyse the rotating Earth/Sun system differently because of the tether.
 

1. How does gravity affect fishing line?

Gravity is the force that pulls objects towards each other. In the case of fishing line, gravity causes it to sag or droop downwards towards the ground. This can affect the presentation of the bait or lure and make it less attractive to fish. It can also cause the fishing line to get tangled or caught on objects underwater.

2. Can gravity affect the casting distance of a fishing line?

Yes, gravity can affect the casting distance of a fishing line. The force of gravity acts on the weight of the fishing lure or bait, pulling it downwards and shortening the distance it can be cast. This is why anglers often use sinkers or weights to counteract the effects of gravity and cast their lines further.

3. How does the weight of the fishing line affect its response to gravity?

The weight of the fishing line can affect its response to gravity. Heavier fishing lines will be more affected by gravity, causing them to sag more and have a shorter casting distance. Lighter fishing lines will be less affected by gravity, giving them a more natural presentation and longer casting distance.

4. Does the angle of the fishing line affect the force of gravity on it?

Yes, the angle of the fishing line can affect the force of gravity on it. The more horizontal the fishing line is, the more it will be affected by gravity and sag downwards. This is why anglers often try to keep their fishing lines at a 45-degree angle to the water's surface to minimize the effects of gravity.

5. How can anglers counteract the effects of gravity on their fishing line?

Anglers can counteract the effects of gravity on their fishing line by using sinkers or weights to increase the weight of their line. They can also try to keep their fishing line at a 45-degree angle to the water's surface and use a lighter fishing line to reduce the effects of gravity. Proper casting techniques and using a longer fishing rod can also help to increase casting distance and minimize the effects of gravity on the fishing line.

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