These hypothetical objects might form if our universe has hidden extra dimensions beyond the three of space and one of time that we can see, scientists say. A new study of five-dimensional black strings offers a glimpse into how these strange objects might evolve over time – if indeed they exist at all. One of the longest outstanding mysteries in physics is how gravity is related to the other fundamental forces, such as electromagnetism. One theory, first proposed in 1919, showed that if an extra dimension is added to the universe, gravity still exists in the first four dimensions (three space dimensions and time), but the way this four dimensional space curves over the extra fifth dimension, naturally produces the other fundamental forces. However, we cannot see or detect this fifth dimension, so it was proposed that the extra dimension was curled up, and hence became invisible to us. This theory was what ultimately led to string theory, and is still included at the heart of most string theory analysis. Did you learn anything about black strings?