# Tag Info

• 10.2k

### Differential form of Lorentz equations

How do these differentials follow from the Lorentz transformations mathematically? And is there a chain rule involved? You simply take the total differentials of the Lorentz transform formula you ...
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Accepted

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1 vote

### Physical Quantities Sign Convention

Any change in either the magnitude or direction of velocity is acceleration. Since velocity is a vector $\vec v$ its negative is a vector pointing in the opposite direction. They are often ...
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1 vote

### Physical Quantities Sign Convention

Negative velocity means it is moving in the opposite direction, however negative acceleration just signifies that its velocity is decreasing at the given rate, to give some examples: If something is ...
1 vote

### Physical Quantities Sign Convention

Velocity is a vector, so minus means head of the vector arrow in the direction of decreasing axis values. Similarly for acceleration and force. But for something to accelerate oppositely still having ...
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### Interior Solution for Black Hole in Particular

This is a weird way of phrasing, but it seems about right. The interior metric for a Schwarzschild black hole can be written as \mathrm{d}s^2=-\left(1-\frac{2M}{r}\right)\mathrm{d}t^2+\left(1-\frac{...
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### How a scalar component can be negative?

A scalar can totally be signed, in which case the minus sign indicates some sort of state rather than spatial direction. For example, an object at $-4^\circ C$ whose rate of change of speed is $-0.5$ ...
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### Can you tell who is moving through time?

By definition every observer is moving through time. In fact, in his own reference frame, am observer only moves through time, and not space. This time is called his Proper Time. If you are asking the ...
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### Can you tell who is moving through time?

Special relativity has two main postulates which are true for any relativistic problem In any reference frame, light travels at the velocity $c$. Every reference frame is equally valid and no ...
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### Can you tell who is moving through time?

However, can you know who is moving through time? In the sense that this phrase has meaning, every massive object is moving through time at $c$. Could you just turn on a flashlight while you are ...
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### Can electric field be negative?

An electric field can be negative. The definition of the electric field is the force experienced by a positive charge in the field. the source particle is negatively charged, then the positive test ...
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