# காலம் - ஒரு அறிவியல் பார்வை
{{< figure
  src="images/twin_paradox.jpg"
  alt=""
  caption="Twin paradox"
>}}

## மேலதிக வாசிப்புக்கு:

1. [What is a "cesium atomic clock"? National Research Council Canada,](https://nrc.canada.ca/en/certifications-evaluations-standards/canadas-official-time/what-cesium-atomic-clock)
    
2. [Optical Clocks: The Future of Time, National Institute of Standards and Technology (NIST), USA.](https://www.nist.gov/atomic-clocks/how-atomic-clocks-work/optical-clocks-future-time) 
    
3. For a simple explantion of spacetime curvature, gravity, and how Einstein’s general theory of relativity explains it, see the video: What is General Theory of Relativity? 
{{< youtube UG4Jz9rNzj8 >}}

4. [Optical Clocks: The Future of Time](https://www.nist.gov/atomic-clocks/how-atomic-clocks-work/optical-clocks-future-time)