Do you gain a day traveling from London to Los Angeles?

Yes, you can gain a day traveling from London to Los Angeles.

When traveling westward, you are "losing" time because you are flying in the opposite direction of the Earth's rotation. This means that when you arrive at your destination, it will be later in the day than it was when you left.

However, when traveling eastward, you are "gaining" time because you are flying in the same direction as the Earth's rotation. This means that when you arrive at your destination, it will be earlier in the day than it was when you left.

In the case of traveling from London to Los Angeles, you would cross over multiple time zones, which means you would gain a day. For example, if you left London at 12:00 pm on Monday and flew westward to Los Angeles, you would arrive at 12:00 pm on Monday Los Angeles time. However, if you left London at 12:00 pm on Monday and flew eastward to Los Angeles, you would arrive at 12:00 pm on Tuesday Los Angeles time.