Hydrogen Bubble Tails (IMAGE) Science China Press Caption This is a vertical view of hydrogen bubble tails of liquid metal tiny motors. The scale bar is 1 cm. Credit ©Science China Press Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.