It seems like everyone in the world has weighed in on the dress. So much that the #TheDress has been trending worldwide for much of the last day. 

After a woman in Scotland posted the picture on social media, a debate of sorts broke out. Some people saw the colors as black and blue, while others were adamant that the dress was white and gold.  

The actual dress is black and blue, but the way that the light reflected led to different perceptions of the colors.

Dr. Marc Siegel explained this morning why everyone is seeing this dress differently.

He said the blue light reflecting off the black and blue dress is what causes the confusion in a person's mind.

Siegel said it all comes down to basic biology from seventh grade. 

"It's the old rods and cones. We've only got 2 percent cones that look for blue. As we get older, we don't see blue as well and we need amplifiers to see blue. So we can be fooled by the light coming in and miss blue and see it as something else," he said. 

"It's not a hoax or an optical illusion, it is straight science."

Watch the full explanation above.