user7141: We all know that we get sick and get old but i have heard that "Abhidhamma" talks about a faster version of decay and change.As i have heard there is a change that is happening every fraction of a second but we are unable to recognize it with our senses.
Does anyone have knowledge to share about this?
And how can we use this to our personal practice?

user295: With vipassanā-ñāṇa you can recognise this change perhaps not to the clarity as in the Abhidhamma.
In p 39 of Process of Conciousness and Matter by (Aggamahāpaṇḍita) Bhaddanta Dr. Rewata Dhamma (Writen as a supplement to Comprehensive Manual of Abhidhamma), gives an idea at what rate phenomena arises and passes away.
For personal practice if will be sufficient recognise:

Arising
Passing
Change, i.e., what has arisen is what has not arisen before 

Also see my other answer on similar subject matter: https://buddhism.stackexchange.com/a/12392/295
Following two articles by Piya Tan might be of interest:

Dhamma and Abhidhamma
The Radiant Mind


7141: <p>We all know that we get sick and get old but i have heard that "Abhidhamma" talks about a faster version of decay and change.As i have heard there is a change that is happening every fraction of a second but we are unable to recognize it with our senses.</p>

<p>Does anyone have knowledge to share about this?</p>

<p>And how can we use this to our personal practice?</p>
 295: <p>With <a href="https://en.wikipedia.org/wiki/Vipassan%C4%81-%C3%B1%C4%81%E1%B9%87a" rel="nofollow noreferrer">vipassanā-ñāṇa</a> you can recognise this change perhaps not to the clarity as in the Abhidhamma.</p>

<p>In p 39 of <a href="http://host.pariyatti.org/treasures/Process_of_Consciousness_and_Matter.pdf" rel="nofollow noreferrer">Process of Conciousness and Matter</a> by (Aggamahāpaṇḍita) Bhaddanta Dr. Rewata Dhamma (Writen as a supplement to <a href="http://store.pariyatti.org/Comprehensive-Manual-of-Abhidhamma-A--PDF-eBook_p_4362.html" rel="nofollow noreferrer">Comprehensive Manual of Abhidhamma</a>), gives an idea at what rate phenomena arises and passes away.</p>

<p>For personal practice if will be sufficient recognise:</p>

<ul>
<li>Arising</li>
<li>Passing</li>
<li>Change, i.e., what has arisen is what has not arisen before </li>
</ul>

<p>Also see my other answer on similar subject matter: <a href="https://buddhism.stackexchange.com/a/12392/295">https://buddhism.stackexchange.com/a/12392/295</a></p>

<p>Following two articles by Piya Tan might be of interest:</p>

<ul>
<li><a href="http://www.themindingcentre.org/dharmafarer/wp-content/uploads/2009/12/26.1-Dhamma-Abhidhamma-piya.pdf" rel="nofollow noreferrer">Dhamma and Abhidhamma</a></li>
<li><a href="http://www.themindingcentre.org/dharmafarer/wp-content/uploads/2009/12/8.3-Radiant-mind.-piya.pdf" rel="nofollow noreferrer">The Radiant Mind</a></li>
</ul>
