It's a combination of knowing when and how fast bacteria multiply, how you can stop bacteria from multiplying, and how you can kill the bacteria that did multiply. Above 40° bacteria will double every 20 minutes. So if you have 5 bacteria on a piece of chicken, at the end of hour 1 you would have 40. At the end of hour 2 you would have 300.
When the surface of whole muscle meats reaches 140° (or the internal temp of ground meat) multiplication of bacteria stops... but it's still alive and well. Now is when the chart that @daveomak posted above comes into play because it takes into account temperature and time expressed as a result of a logarithm often referred to as a log reduction. The higher of a log number, the higher percentage of pathogens are killed. A 5-log reduction means that 99.999% of bacteria will be killed. A 7-log number means that 99.99999% of bacteria will be killed.
Using a chicken wing as the example, when the surface temp reaches 150°, it will take 5 minutes at that temperature to kill 99.99999% of the surface bacteria. If you allow the internal temp of a chicken wing to reach 150°, and could hold that temperature for 5 minutes, the wing can be eaten because 99.99999% of the bacteria will be dead. The USDA does not keep log reduction numbers a secret, but they do like to publish safe numbers because they are easy to remember. This is why the USDA says to cook chicken to 165°, and if you look back at the chart it says 0 minutes of holding time is needed before eating. The problem is that 150° chicken, held for 5 minutes has a soft texture. But 156° chicken held at least 1 min
So by cooking internal temp to 170 it will be safe am I right