# Planck length at high speed

• I
• windy miller
In summary: So the simple solution is that length contraction is just a matter of perspective and not a physical change to the object itself. In summary, a ruler of one Plank length sent on a rocket close to the speed of light would experience length contraction, regardless of its physical size. The Plank length itself has no effect on physics and is just a human measure of distance. The concept of length contraction is a matter of perspective and does not physically change the object.

#### windy miller

Imagine I had a ruler 1 Planck length long, I then send it on a rocket close to the speed of light, does its length contract? It seems to my simple intuition, relativity would say yes and Qm would say no. Is there a simple solution to this ?

windy miller said:
Imagine I had a ruler 1 Planck length long, I then send it on a rocket close to the speed of light, does its length contract? It seems to my simple intuition, relativity would say yes and Qm would say no. Is there a simple solution to this ?
I don't think making the ruler that short is likely to make a difference. Special relativity and quantum mechanics are perfectly compatible (via Quantum Field Theory). There would be length contraction, regardless of the physical size of the ruler.

(1) The Plank length is just a made-up human measure of distance and has no effect on physics. You might as well be asking if a meter stick would be subject to length contraction

(2) You WOULD have a problem since as far as is known, you could not construct a ruler that is one Plank unit long.

(3) All of that is moot anyway since your question implies that you think length contraction is something that happens to an object, but it isn't. It is an observation by someone in a frame of reference that is moving relative to the object.

Mlesnita Daniel, windy miller, Frimus and 1 other person

## 1. What is the Planck length at high speed?

The Planck length at high speed refers to the smallest possible length that can be measured in the universe, according to the theory of relativity. It is approximately 1.616199 × 10^-35 meters.

## 2. Why is the Planck length considered the smallest unit of measurement?

The Planck length is considered the smallest unit of measurement because it is the length at which the effects of quantum gravity become significant. At this scale, the classical laws of physics break down and a more comprehensive theory is needed.

## 3. Can objects actually travel at the speed of light in relation to the Planck length?

No, according to the theory of relativity, it is impossible for any object with mass to travel at the speed of light. However, the Planck length can be used as a reference point when discussing the effects of high speeds on objects.

## 4. How does the Planck length change at high speeds?

At high speeds, the Planck length does not change. It remains a constant value and is not affected by the speed of objects. However, the perception of length may change due to the effects of time dilation and length contraction.

## 5. Are there any practical applications of the Planck length at high speeds?

Currently, there are no practical applications of the Planck length at high speeds. However, understanding the relationship between speed, time, and distance at the smallest scale can help us gain a better understanding of the fundamental laws of the universe.