Understanding General Relativity: Gravity Warping Space-Time

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Discussion Overview

The discussion revolves around the interpretation of general relativity in relation to the energy requirements of locomotives based on their mass. Participants explore analogies and seek clarification on how gravity warps space-time and its implications for motion, particularly in the context of a flat grade scenario.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that a heavier locomotive requires less energy to maintain speed due to gravity warping space-time, likening it to a bowling ball on a mattress.
  • Another participant challenges this claim, stating that a more massive locomotive actually requires more energy to maintain speed, citing various factors that influence energy requirements.
  • A question is raised about whether the locomotive is traveling down a tunnel or on a flat grade, seeking to clarify the scenario further.
  • It is confirmed by a participant that the locomotive is on a perfectly flat grade, leading to agreement with the previous challenge against the initial claim.

Areas of Agreement / Disagreement

Participants express disagreement regarding the initial claim about energy requirements related to mass and general relativity. There is no consensus on the accuracy of the analogy presented by the first participant.

Contextual Notes

The discussion includes assumptions about the effects of general relativity on locomotives, which are noted to be negligible in practical scenarios. The implications of mass and energy requirements are also dependent on various factors not fully explored in the conversation.

Bobbyam
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Hi, I was an armchair student of physics some time ago, so I appreciate your patience with me. I was on a tour of the lost Atlantic Avenue tunnel in Brooklyn and I'm hoping someone can give me more insight, perhaps an analogy, to help me imagine this better. If I understood him right, this was mind blowing to me because for the first time I could glimpse actually understanding something of general relativity. The tour guide said that the heavier a locomotive is, the less energy is required to maintain its speed. This is because gravity is warping space time, like a bowling ball in a mattress, and the heavier locomotive, having more mass and more gravity, is actually "falling" through a space-time hole. Is this right? Can anyone add to it? Thank you.
 
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None of that is true, or even vaguely accurate. Sorry.

Most blatantly, the overall premise doesn't make any sense: the more massive a locomotive is, the more energy is required to keep it going---even neglecting high order effects (i.e. the details of the wheels, engine, air-resistance, wheel-track interface, etc).

For instance: how much energy does it take to keep a model train going? Is that more or less than a full size locomotive?

Now, as far as the general relativity: any GR effects for a locomotive staying on the surface of Earth would be extremely negligible. Like, extremely, extremely. Even more importantly, if---for some reason---GR effects were important, they would still make it harder to maintain a given speed for a larger mass.
 
Thank you!
 
Bobbyam said:
Hi, I was an armchair student of physics some time ago, so I appreciate your patience with me. I was on a tour of the lost Atlantic Avenue tunnel in Brooklyn and I'm hoping someone can give me more insight, perhaps an analogy, to help me imagine this better. If I understood him right, this was mind blowing to me because for the first time I could glimpse actually understanding something of general relativity. The tour guide said that the heavier a locomotive is, the less energy is required to maintain its speed. This is because gravity is warping space time, like a bowling ball in a mattress, and the heavier locomotive, having more mass and more gravity, is actually "falling" through a space-time hole. Is this right? Can anyone add to it? Thank you.
So, not knowing the situation, is this locomotive going down in a tunnel or traveling flat in a tunnel?
 
It's supposedly on a perfectly flat grade.
 
Bobbyam said:
It's supposedly on a perfectly flat grade.
In that case I fully agree with zhermes
 

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